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2011 seminars at IFSI
20 Dicembre 2011, 14:00 ‐ Aula IB09
Dr. Paul Goldsmith (NASA‐JPL)
"Molecular Oxygen in the Galaxy: latest results from the Herschel satellite"
Abstract: Oxygen is the third most abundant element in the cosmos. In the gas phase, oxygen can be
ionized, atomic, or in molecular, and it is also incorporated into interstellar grains. Models of the gas‐phase
chemistry in dense clouds predict molecular oxygen (O2) to be almost as abundant as carbon monoxide
(CO). A number of searches for molecular oxygen have been carried out, including ground‐based searches
for the isotopologue 16O18O and searches for O2 in redshifted galaxies. Searches for Galactic O2 carried
out with the SWAS and Odin spacecraft have yielded upper limits on the abundance of molecular oxygen
typically 1 to 2 orders of magnitude below those predicted by gas‐phase models. There has been a
detection of a single transition of O2 in one source, again indicating a low abundance. A variety of
explanations have been proposed to explain this low abundance. Some of these are based on depletion of
atomic oxygen onto dust grains, resulting in incorporation of this species into water that remains on the
grain surface. Available gas‐phase oxygen is largely incorporated into CO, leaving little for gas‐phase O2.
Other models involve circulation of material between UV‐irradiated and well‐shielded regions, and highly
clumpy cloud structure.
The Herschel Open Time Key Project ``HOPʼʼ (Herschel Oxygen Project) addresses this important problem in
astrochemistry, exploiting the high angular resolution and sensitivity of the Herschel HIFI instrument to
observe 3 rotational transitions of O2 in a broad sample of molecular clouds. The sensitivity and angular
resolution of HIFI are dramatically better than what has previously been available at these frequencies. We
will discuss the HOP observations to date, focusing on the detection of O2 towards the H2 Peak 1 position
near KL in Orion. This region has some interesting compact molecular sources that have emission in the
same velocity range as found for the observed O2 lines and we explore a model based on warming grains
and restoration of gas phase chemistry that can explain our observations. This region is also heavily
impacted by the molecular outflow and resulting shocks which are manifest in the highly‐structured
emission from pure rotational and rotation‐vibration transitions of molecular hydrogen. We discuss low‐
velocity C‐shock models that can produce the observed column density of O2. We will conclude with a
discussion of some of the implications for oxygen chemistry in dense interstellar clouds.
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13 Dicembre 2011 ore 11:00 Aula IB09 ‐ Edificio U
Dr. Miguel Pereira Santaella (Centro de Astrobiología di Madrid ‐ CSIC/INTA)
"Local Luminous Infrared Galaxies. AGN Activity from Spitzer/IRS spectra"
Abstract: Luminous infrared galaxies (L_IR = 10^11 ‐ 10^12 L_sun) are major contributors to the star‐
formation rate density of the universe at z~1‐2. In the local universe 50% LIRGs show AGN or composite
AGN/starburst nuclear activity from optical spectroscopy. We used mid‐IR line diagnostics and spectral
decomposition to estimate the AGN bolometric contribution to the IR luminosity. We found that, although
the AGN detection rate is ~50%, only 10% of the local LIRGs have significant AGN contribution
L_agn(bol)/L_IR > 0.25.
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Venerdì 25 Novembre 2011 Aula IB09 ore 11:00 ‐ Aula IB09
Prof. Daniel Gomez (IAFE and Department of Physics, University of Buenos Aires, Argentina)
"Magneto‐hydrodynamic simulations in solar and space physics"
Abstract: Because of its proximity, our Sun provides a unique opportunity to perform high resolution
observations of its outer layers. We can also theoretically model many of the fascinating physical
phenomena taking place on the Sun, as well as their impact on the solar system.
The large scale behavior of these phenomena can be properly studied within the framework of magneto‐
hydrodynamics. We assume a fully ionized hydrogen plasma and adopt the more comprehensive two‐fluid
magneto‐hydrodynamic approximation. For problems such as the solar wind or magnetic loops in the solar
corona, which are shaped by a relatively strong mean magnetic field, the reduced magneto‐hydrodynamic
approximation is adopted. We will review the basic features of two‐fluid MHD, and focus on potential
applications to the dynamics of the solar wind.
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19 Ottobre 2011, 11:00 ‐ Aula IB09
Dott. Shinichi Shirono, Università di Nagoya
"Differentiation of silicate particles from ice in a small body induced by ripening"
Abstract: A probable scenario of differentiation between silicate‐ice in an icy object is a settling of a silicate
particle in water followed by the melting event of the object. To proceed the settling, the size of a particle
should be large enough such that the settling velocity exceeds the background flow velocity induced by
thermal convection. In this paper, I derived the critical sizes required for settling and timescale for growth
to those sizes through ripening. It is found that the settling is possible if the silicate particles coagulate each
other to form a network in water. If the particles do not coagulate, the settling is not probable because the
time required to growth is enormously large. The coagulation of silicate particles strongly depends on pH of
water. Composition of the ice required for differentiation is discussed.
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13 October 2011, 14:30 ‐ Aula IB09
Prof. Yasuo Fukui, Department of Physics Nagoya University
" Large scale CO survey with NANTEN: The Milky Way and the Magellanic System "
Abstract: CO is a fundamental molecule for probing dense phase of the interstellar medium. I present the
major results of the CO survey made with NANTEN 4m telescope in Chile. The talk will cover the high‐mass
star forming regions, the Central Molecular Zone and the Magellanic System. I also present recent results of
the on‐going correlation studies with gamma rays and infrared radiation.
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07 June 2011, 11:00 ‐ Aula IB09 Edificio U, ARTOV
Gemma Busquet (INAF‐IFSI)
"Timing the chemical evolution of the dense gas in high‐mass star forming regions"
Abstract: It is well known that N‐bearing molecules, such as NH3 and N2H+, are excellent tracers of the
interstellar dense gas because none of these molecules deplete onto dust grains until densities reach ~10^6
cm‐3.
Thus observations of these dense gas tracers have become a powerful tool to study the sites of star
formation. However, only a few observational studies have focused on the comparison of NH3 and N2H+
cores, and these studies, which were carried out toward low‐mass star‐forming regions, find that the
NH3/N2H+ abundance ratio is around 140‐190 in starless cores, while it decrease to 60‐90 close to young
stellar objects (YSOs). In the intermediate‐mass cores surrounding the high‐mass star IRAS20293+3952,
Palau et al. (2007) find the same trend, with low values, around 50, for cores associated with YSOs and high
NH3/N2H+ ratio, up to 300, in the cores with starless properties, clearly showing that chemical
differentiation is important in the region. All these works show that the NH3/N2H+ abundance ratio is
consistent with being a chemical clock.
In this talk I'll present high angular resolution observations of NH3 and N2H+ toward a sample of
intermediate/high‐mass star forming regions in order to investigate whether the differences seen in NH3
and N2H+ are related to the chemical evolution of dense gas. Our sample contains cores in different
evolutionary stages, from pre‐protostellar core candidates to protostellar cores harboring hot molecular
cores and UCHII regions in the process of clearing up its molecular material. We additionally applied the
time‐dependent chemical model UCL_CHEM in the massive protocluster AFGL 5142 to qualitatively
reproduce the abundances of the region.
We found significant differences in the mean NH3/N2H+ ratio values between pre‐protostellar and
protostellar cores, being higher during the pre‐protostellar phase, which is consistent with previous results.
What is more, we found an evolutionary sequence of the NH3/N2H+ ratio. Initially, during the pre‐
protostellar phase the NH3/N2H+ seems to decrease as the core approaches the onset of star formation
due to a golden period of NH3 observed in this phase. On the other hand, we found some hints of dense
gas evolution during the protostellar phase, starting with a decreasing trend of the NH3/N2H+ ratio as a
consequence of a golden period of N2H+ until some point that the NH3/N2H+ increases considerably as a
consequence of the temperature increase and/or molecular outflow interaction.
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24 May 2011, 11:00 ‐ Aula IB09 Edificio U, ARTOV
A.A. Berezhnoy (Sternberg Astronomical Institute, Moscow, Russia)
"Dynamical changes of the polar cap potential structure: an information theory approach "
Abstract: Meteoroid impacts lead to production of metal atoms as well as metal oxides and hydroxides in
the exospheres of the Moon and Mercury. The abundances of the main Na‐, K‐, Ca‐, Fe‐, Al‐, Mg‐, Si‐, and
Ticontaining species delivered to these exospheres during meteoroid impacts were estimated. Most
impactproduced molecules that contain metals are destroyed by solar photons while on ballistic
trajectories.
Condensation of dust grains can significantly reduce the concentrations of impact‐produced atoms. Na, K,
and Fe atoms are delivered to the exosphere directly by impacts while Ca, Al, Mg, Si, and Ti atoms are
produced by the photolysis of their oxides and hydroxides. Energies of Na, K, Ca, and Mg atoms produced
via photolysis of the respective monoxides are estimated to be 0.4, 0.35, 0.6, and 0.45 eV, respectively. The
column densities of impact‐produced metal atoms in the lunar exosphere during the peaks of activity of the
main meteor showers are estimated. The Na supply rate is estimated to be 2 ∙ 104, 3 ∙ 103, 104, and 2 ∙ 104
atoms cm‐2 s‐1 for sporadic meteoroids, Perseid, Geminid, and Quadrantid meteor showers, respectively.
A low upper limit on Ca abundance in the lunar exosphere is explained by the condensation of Ca into dust
grains during expansion of the cooling impact‐produced vapor cloud. The relative content of
impactproduced Na and K atoms is maximal at altitudes of about 1000‐2000 km and during the main
meteor showers, lunar eclipses, and passages of the Moon through the Earth’s magnetosphere.
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19 May 2011, 11:00 ‐ Aula Convegni, ARTOV
Igino Coco (INAF‐IFSI)
"Dynamical changes of the polar cap potential structure: an information theory approach "
Abstract: Some features, such as vortex structures often observed through a wide spread of spatial scales,
can lead to think ionospheric convection is turbulent and complex in nature. Here, applying concepts from
information theory and complex system physics we firstly evaluate the Shannon entropy, S, associated with
the polar cap potential obtained from the Super Dual Auroral Radar Network (SuperDARN) and, then,
estimate the degree of complexity of ionospheric convection in different interplanetary magnetic field
conditions. The aforementioned quantities have been computed starting from time series of the
coefficients of the 4th order spherical harmonics expansion of the polar cap potential for three periods,
characterized by: i) steady IMF Bz > 0, ii) steady IMF Bz < 0 and iii) a double rotation from negative to
positive and then positive to negative Bz. A neat dynamical topological transition is observed when the IMF
Bz turns from negative to positive and vice versa, pointing toward the possible occurrence of an
order/disorder phase transition, which is the counterpart of the large scale convection rearrangement and
of the increase of the global coherence. This is also confirmed by the above analysis made on a larger data
base of about twenty days of SuperDARN data, allowing to investigate the role of IMF By. We propose that
the idea that a first‐order like phase transition accompanies magnetospheric dynamics in response to solar
wind changes, has to be extended to the coupled magnetosphere‐ionosphere system during the
intensification of the ionospheric convection in correspondence of southward turnings of the IMF Bz
component.
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18 May 2011, 11:00 ‐ Aula IB09 Edificio U, ARTOV
Alessandro Damiani (Physics Department, University of Santiago de Chile ‐ Santiago, Chile)
" Solar energetic particle events: a natural laboratory for testing our understanding of the middle
atmosphere "
Abstract: Among solar‐terrestrial coupling phenomena, solar energetic particle (SEP) events play a
significant role. They consist of transient particle (mainly proton) emissions from the Sun, associated with
solar flares and coronal mass ejections generally driven by shock waves. They travel in the interplanetary
medium and can enter the terrestrial polar atmosphere if the solar source region is well connected to the
Earth magnetically.
Middle atmospheric variability induced by SEP events was underlined since the Seventies (e.g., Crutzen et
al., 1975), but the recent availability of many satellite sensors added new and interesting features on the
topic. SEPs produce enhanced ionization roughly between 90 Km and 30 Km, with the consequent
triggering of reaction paths, connected to both ion and neutral chemistry, which enhance the abundance of
reactive components such as NOx (N + NO + NO2), HOx (H + OH + HO2) and, secondary, ClOx (ClO + HOCl).
Hence, their efficient catalytic cycles decrease the ozone levels in both stratosphere and mesosphere. The
SEP impact on the atmosphere is traditionally identified as long‐term effects, associated with the lasting of
NOx‐induced ozone depletion, and short‐term effects HOx.
A case study referred to the impact of SEPs of 17 and 20 January 2005 on the middle atmosphere is shown.
Data coming from limb sounder instruments together with preliminary modeling results are presented
witha special emphasis on the short‐term changes of HOx and ClOx species.
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18 May 2011, 10:30 ‐ Aula Convegni, ARTOV
Guy Consolmagno (Specola Vaticana)
"What Every Planetary Astronomer Ought To Know About Meteorites "
Abstract: Dr. Guy Consolmagno SJ, curator of meteorites at the Specola Vaticana, will give a one‐hour
seminar on meteoritics, with a special emphasis on aspects of particular interest to planetary scientists
studying small bodies in the solar system.Included will be a general outline of the chemical classification
scheme (which carbonaceous chondrites have no chondrules? Which have no carbon? Why are both types
classified into the same group?); what can be learn from studying isotope anomalies; and what physical
properties can tell us about meteorite origins and evolution of their parent bodies. A special emphasis will
be on the how the basaltic meteorites thought to come from Vesta may have been formed.
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17 May 2011, 11:00 ‐ Aula IB09 ore 11:00 Edificio U, ARTOV
Nicola Marchili,Max‐Planck‐Institut fuer Radioastronomie (MPIfR), Bonn
"Fast variability of compact extragalactic radio sources"
Abstract: Among radio‐loud Active Galactic Nuclei (AGN), the most compact sources are generally
characterized by a high degree of flux density variability, with timescales ranging from weeks to years. In
the '80s, it has been discovered that a considerable amount of flat‐spectrum radio sources shows variability
in the radio band on timescales as short as one day. This is referred to as IntraDay Variability (IDV). Given
the rapidity of the variations, IDV sets a severe constraint on the size of the emitting region, with deep
implications concerning the physics of AGNs.
I will shortly introduce the phenomenon, discussing the models which have been proposed to explain it.
More than 20 years of studies drew to the conclusion that IDV is caused by InterStellar Scintillation, but
recent results demonstrate that the picture may be much broader, involving the Earth atmosphere and the
solar wind. It is likely that also the structure of the AGN emitting region plays an important role in IDV.
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10 May 2011, 11:00 ‐ Aula IB09 Edificio U, ARTOV
Kazi Rygl (INAF‐IFSI)
"Trigonometric parallaxes of interstellar masers in massive star‐forming regions"
Abstract: Star‐forming regions trace the spiral structure of the Galaxy. For understanding the spiral
structure of the Galaxy trustworthy distances are necessary. Accurate distances are also a crucial
parameter for establishing the mass, size, and luminosity of an object. The most accurate method to
measure the distance is the trigonometric parallax. Using the European VLBI Network we measured, for the
first time, parallaxes of 6.7 GHz methanol masers. This transition belongs to the strongest maser species in
the Galaxy, it is stable and observed toward numerous massive star‐forming regions. We measured
distances and proper motions of five maser sources, and obtained their 3‐dimensional space velocities.
Similar to previous studies, these star‐forming regions rotate slower than Galactic rotation.
After these results I will continue with our new methanol maser project of measuring distances toward the
famous Cygnus X region. Finally, I will introduce the Bar and Spiral Structure Legacy Survey (BeSSeL Survey),
a VLBA Key Science project. BeSSeL will measure parallaxes and proper motions toward more than 400 star‐
forming regions to study the spiral structure and kinematics of our Milky Way.
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29 April 2011, 11:00 ‐ Aula IB09 Edificio U, ARTOV
Dr. Luca Sorriso‐Valvo (IPCF ‐ CNR ‐ Liquid Crystal Laboratory, Cosenza)
"On the MHD turbulent cascade in polar, fast solar wind"
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18 April 2011, 15:00 ‐ Aula IB09 Edificio U, ARTOV
Christina Plainaki (INAF‐ IFSI)
"Generation of Europa's exosphere"
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14 April 2011, 10:30 ‐ Aula IB09 Edificio U, ARTOV
Susan Conway (Laboratoire de Planétologie et Géodynamique Université de Nantes Francia)
"What can impact craters tell us about martian climate?"
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21 March 2011, 11:00 ‐ Aula IB09 Edificio U, ARTOV
Trenchi Lorenzo (INAF‐IFSI)
“Ricostruzione di strutture di plasma coerenti mediante la tecnica Grad ‐ Shafranov.”
Abstract: La tecnica di ricostruzione Grad Shafranov è un metodo che consente la ricostruzione di strutture
di plasma/campo magnetico coerenti che abbiano una geometria bi‐dimensionale mediante l’analisi dei
dati di un singolo satellite. Tale tecnica è stata utilizzata per ricostruire strutture nel vento solare, alla
magnetopausa terrestre e nella coda geomagnetica. Determinare le dimensioni, l’orientazione dell’asse
invariante e l’equilibrio presente all’interno di tali strutture è importante in quanto può dare valide
indicazioni riguardo alla loro origine.
Nell’ambito del seminario vengono illustrati i passi fondamentali per effettuare la ricostruzione Grad
Shafranov e vengono proposti alcuni esempi di ricostruzione basati sui dati raccolti dai satelliti ampte/irm,
wind, Themis e Double Star TC‐1.
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3rd of March 2011, 11:30 ‐ Aula IB09, ARTOV
Dr. Diego Turrini, INAF‐IFSI Rome
Vesta, Ceres and the origins of the Solar System
Abstract: Through its connection with HED meteorites, Vesta is known as one of the first bodies to have
accreted and differentiated in the Solar Nebula, predating the formation of Jupiter and surviving the violent
evolution of the early Solar System. The formation time of Ceres instead is unknown, but it should not
postdate that of Jupiter by far. In the framework of our studies in preparation to the arrival of Dawn
mission, we modelled the collisional histories of Vesta and Ceres at the time of the formation of Jupiter,
assumed to be the first giant planet to form. Our results clearly indicate that the formation of the giant
planet caused an intense early bombardment, which we labelled the Jovian Early Bombardment, in the
orbital region of the Main Asteroid Belt. According to our results, Vesta and Ceres would not have survived
the Jovian early bombardment if the disk was populated mainly by large planetesimals like those predicted
to form in turbulent circumstellar disks. Disks dominated by small bodies, like those predicted to form in
quiescent circumstellar disks, or with a varying fraction of the mass in the form of larger planetesimals
represent more favourable environments for the survival of the two asteroids. Across the Jovian Early
Bombardment, both asteroids had their surfaces saturated by craters as big as 150 km and a few as big as
200 ‐ 300 km. In the case of Vesta, the Jovian early bombardment would have significantly eroded (locally
or globally) the crust and possibly caused effusive phenomena similar to the lunar maria, whose
crystallisation time would then be directly linked to the time of the formation of Jupiter.
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31 January 2011, 11:30 ‐ Aula IB09, ARTOV
Dr. Leonardo Testi (European ALMA Project Scientist )
Circumstellar disks and the dawn of planetary systems
Abstract: Circumstellar disks are formed during the early phases of protostellar collapse. Disks allow matter
to loose angular momentum and accrete onto the central protostar in the early phases of stellar evolution,
but are also the location where planetary systems form. In this talk I will review our current understanding
of the structure and evolution of disks around solar mass pre main sequence stars and the first steps
towards the formation of planetary systems.
I will mainly focus on the timescales and physical processes related to disk evolution and the evolution of
the solid component (dust and pebbles) in disks.
2010 Seminars at IFSI:
29 November 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. Christina Plainaki (IFSI‐INAF Roma)
FISICA DELLA RADIAZIONE COSMICA SOLARE: IL MODELLO NMBANGLE PPOLA
Abstract: Questo seminario rientra nel campo della fisica della radiazione cosmica solare. Il tema specifico
del seminario sarà la presentazione del modello NMBANGLE PPOLA (Neutron Monitor Based Anisotropic
GLE Pure Power Law model) che pone in relazione la radiazione cosmica solare primaria che arriva al limite
superiore dell'atmosfera terrestre, con quella secondaria registrata sulla Terra dalla rete delle stazioni di
Neutron Monitor durante le grandi eventi solari di protoni energetici (SEP ‐ Solar Energetic Particles). Gli
eventi di SEPs, alcune volte, possono produrre ‐‐ in modo indiretto‐ aumenti dell'intensità della radiazione
cosmica registrata nei Neutron Monitors producendo un episodio GLE (Ground Level Enhancement of Solar
Cosmic Rays). I GLEs, devono la loro origine all'arrivo nelle vicinanze della terra di particelle solari
relativistiche, distribuite in latitudine e longitudine in maniera dipendente sia dalla direzione della loro
velocità iniziale sia dal campo magnetico interplanetario e terrestre. Il modello NMBANGLE PPOLA in effetti
è una nuova versione del modello precedente NMBANGLE, sviluppata considerando un diverso spettro
solare. Il modello usa i dati da 33 Neutron Monitor collocati in diversi punti sulla Terra e, considerando il
modello Tsyganenko per il campo magnetico della Terra più la fisica dell'atmosfera, effettua una tecnica
back‐tracing con lo scopo di dedurre il valore di diversi parametri solari. Gli output del modello sono: a) lo
spettro solare ricostruito durante un GLE b) distribuzione in latitudine o longitudine del flusso della
primaria radiazione cosmica solare fuori l'atmosfera terrestre, c) evoluzione nel tempo del flusso della
primaria radiazione cosmica solare d) identificazione dell'anisotropia dei raggi osmici solari durante
l'evento. Di conseguenza, questo modello offre un'immagine completo dello sviluppo dell'evento solare
utilizzabile per applicazioni di monitoraggio dello Space Weather.
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28 October 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. Abraham C.‐L. Chian (National Institute for Space Research (INPE), Brazil & California Institute of
Technology (Caltech), USA)
Amplitude‐phase synchronization and intermittent turbulence in the earth‐ocean‐space environment
Abstract: The origin and nature of intermittent turbulence in the earth‐ocean‐space environment is
analyzed in observational data and numerical simulations. First, we apply onlinear techniques of kurtosis
and surrogate data to quantify the degree of amplitude‐phase synchronization in intermittent turbulence in
space plasmas, atmosphere and ocean. Next, we demonstrate the duality of amplitude‐phase
synchronization in intermittent turbulence seen in a nonlinear model of solar dynamo and a nonlinear
model of tsunami and plasma drift‐waves. The amplitude‐phase synchronization related to multiscale
interactions is shown to be responsible for the formation of coherent structures in intermittent turbulence
in fluids and plasmas. The role of on‐off intermittency in the variability of solarinterplanetary magnetic field
and its impact on climate change and space weather, and in natural disasters such as tsunami driven by
earthquake or weather storm is discussed.
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21 July 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. Anders Jerkstrand (Department of Astronomy, Stockholm University)
Late time supernova emission from gamma rays to the infrared
Abstract: After a few weeks, supernovae are powered by radioactive elements produced in the explosion.
The gamma rays and high‐energy electrons and positrons heat, ionize and excite the gas, which then
reemits radiation in the UV/optical/NIR range. At late times, low temperatures and dust cause most of the
energy to emerge in the far‐infrared. I briefly describe the mechanisms of late‐time supernova emission,
and the observations of them.
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08 July 2010, 15:00 ‐ Aula IB09, ARTOV
Dr. Joe Borovsky (Los Alamos National Laboratory, Los Alamos, NM 87545, USA)
Solar‐Wind Structure and the Kolmogorov Spectrum
Abstract: Strong discontinuities can dominate the spectral power of the solar wind and the Kolmogorov f ‐
5/3 power‐law spectrum can be produced from a time series of strong discontinuities extracted from solar‐
wind measurements. Strong discontinuities represent structure in the solar‐wind plasma, not turbulence.
Using measurements from the ACE spacecraft and using numerical experiments, the connection between
the properties of the solar‐wind plasma and the Kolmogorov f ‐5/3 spectrum is explored.
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23 June 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. Giuseppe Mitri (California Institute of Technology, Division of Geological and Planetary Sciences)
Mountains on Titan: Modeling and Observations
Abstract: We have developed a thermal model of Titan's interior to study changes in volume during partial
freezing or melting of a subsurface ocean due to heat flux variations from the interior. We find that the
long‐term cooling of Titan can cause global volume contraction. We then simulate two‐dimensional
contractional deformation of Titan's icy lithosphere, finding that contractional deformation can produce
tectonic activity and fold formation. Folds could potentially achieve a topographic height of several
kilometers for high temperature gradients in the ice I shell (order of 10 K km^‐1), corresponding to an
ancient high heat flux from the interior (order of 0.03 ‐ 0.06 W m^‐2). Examination of Synthetic Aperture
Radar (SAR) imagery obtained by Cassini Radar shows possible evidence of contractional tectonism in the
equatorial regions of Titan, although the moderate resolution of the Cassini SAR imagery does not permit
an unambiguous geological interpretation.
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18 June 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. Giuseppe Mitri (California Institute of Technology, Division of Geological and Planetary Sciences)
Interior Structure and Accretion of Titan
Abstract: Titan's normalized moment of inertia as inferred by gravity coefficients and hydrostatic
equilibrium theory is C/MR^2 ~ 0.34 (Iess et al., 2010). We show that Titan's deep interior (~2,100 km
radius) is likely composed of a mixture of ice and rock indicating a partial differentiation. In order to avoid
melting and complete segregation of rock and ice, Titan must be formed relatively late, > 2.6 Myr after the
calcium‐aluminum‐rich inclusions (CAIs), and the accretion must have occurred on a timescale > 0.1 Myr.
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10 June 2010, 11:30 ‐ Aula IB09, ARTOV
Dr. S.F. Colosimo (IFSI/INAF Roma)
RADIATIVE TRANSFER MODELLING OF CLOUDS VERTICAL PROFILE FOR SATURN'S ATMOSPHERE BY MEANS
OF CASSINI/VIMS DATA
Abstract: A simple study of clouds vertical profile on Saturn is presented here using VIMS images.
VIMS (Visible Infrared Mapping Spectrometer) is an image spectrometer on board the Cassini spacecraft,
which has orbited the ringed planet since July 2004. The instrument is capable of acquiring simultaneously
an image with its corresponding spectral information in the visible and near infrared range between 0.3 and
5.2 microns.
A Radiative Transfer (RT) model has been used to simulate the radiance of the planet and a spectral
database has been created in order to fit the instrument spectra. The best fit with the signal has been
found using different levels of aerosols and clouds. In the spectral interval 1.0 3.5 microns, VIMS spectra
are very sensitive to the vertical distribution of aerosols in the upper troposphere and lower stratosphere.
In the thermal part of the spectrum (4.4‐5.2 microns), where the instrument sounds the deeper
atmospheric levels, the RT model reveals the need for thick deep clouds in order to fit the data.
A comparison of best fit spectra among different latitudes in the southern hemisphere has shown that the
altitude of cloud decks, opacity, and optical properties vary across latitudes.
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03 June 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. Sergio Molinari (INAF/IFSI‐Roma)
Primi risultati di Herschel per Hi‐GAL, la Survey del Piano Galattico
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14 May 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. J. Brad Dalton, III (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California)
Surface Composition of Europa: Windows to the Interior
Abstract: The surface deposits of Europa provide our most direct means of understanding the composition
of its interior ocean. Application of cryogenic reflectance spectroscopy to observations from the Galileo
Near Infrared Imaging pectrometer (NIMS) now allows us to derive abundances of surface materials in
independent geologic units. The unique spectral signatures of hydrated sulfur compounds and brines
provide a powerful method to distinguish surface materials derived from the interior (endogenic) from
those created by charged‐particle radiation (exogenic). Recent results indicate that hydrated sulfuric acid is
present over the entire surface, with a concentration linked to the magnetospheric energy lux – and
independent of underlying geologic composition. At the same time, the compositions of individual geologic
units are consistent among units of the same type, such as lenticulae, chaos, or ridged plains. It is not yet
clear from the Galileo observations whether the surface deposits contain endogenically‐created sulfuric
acid as well. However, it is clear that the surface deposits have retained compositional signatures that
constrain the composition of the subsurface liquid reservoir. With appropriate spectral and spatial
resolution, future missions should be able to unravel these influences and provide deeper understanding of
Europa and Ganymede, their formation and evolution, and their astrobiological potential.
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29 March 2010, 15:00 ‐ Aula IB09, ARTOV
Dr. Nick Schneider (LASP, U. Colorado)
STUDIES OF ATMOSPHERIC ESCAPE: IO, ENCELADUS AND MARS
Abstract: Groundbased and spacebased studies of atmospheric escape form a focus of research at the
University of Colorado. I will describe three case studies: groundbased studies of escape from Io and
Enceladus, and a NASA Mars Scout mission nearing the Preliminary Design Review stage. For groundbased
studies, we use high‐resolution spectroscopy to track the escape of sodium as a tracer element. At Io,
sodium studies have identified multiple non‐thermal escape paths, and recent observations with the TNG
have found yet another whose origin is unknown. At Enceladus, we have used sodium as a marker of a
subsurface ocean, and found that if there is such an ocean, it must lie so deep that the evaporation that
drives the eruptions occurs under pressure. Finally, I will discuss MAVEN, a NASA Mars Scout mission whose
objective is to test the hypothesis that a once‐habitable Mars lost its atmosphere to space. MAVEN
undertakes a complete examination of atmospheric escape from Mars today, in the context of its current
atmospheric state and the variable drivers of solar wind and EUV flux. These measurements will enable a
backwards extrapolation of the Mars atmosphere under the conditions of the energetic early Sun, and a
test of whether the violent conditions of the early Sun were adequate to strip away its former atmosphere.
My presentation will emphasize the role of the Imaging UV Spectrograph.
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14 May 2010, 11:00 ‐ Aula IB09, ARTOV
Dr. J. Brad Dalton, III (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California)
Surface Composition of Europa: Windows to the Interior
Abstract: The surface deposits of Europa provide our most direct means of understanding the composition
of its interior ocean. Application of cryogenic reflectance spectroscopy to observations from the Galileo
Near Infrared Imaging Spectrometer (NIMS) now allows us to derive abundances of surface materials in
independent geologic units. The unique spectral signatures of hydrated sulfur compounds and brines
provide a powerful method to distinguish surface materials derived from the interior (endogenic) from
those created by charged‐particle radiation (exogenic). Recent results indicate that hydrated sulfuric acid is
present over the entire surface, with a concentration linked to the magnetospheric energy flux – and
independent of underlying geologic composition. At the same time, the compositions of individual geologic
units are consistent among units of the same type, such as lenticulae, chaos, or ridged plains. It is not yet
clear from the Galileo observations whether the surface deposits contain endogenically‐created sulfuric
acid as well. However, it is clear that the surface deposits have retained compositional signatures that
constrain the composition of the subsurface liquid reservoir. With appropriate spectral and spatial
resolution, future missions should be able to unravel these influences and provide deeper understanding of
Europa and Ganymede, their formation and evolution, and their astrobiological potential.
2009 Seminars at IFSI
9 October, 15:00 ‐ Aula IB09, ARTOV
Dr. Kenneth L. Tanaka (U.S. Geological Survey, Flagstaff, Arizona USA)
Geology of the polar regions of Mars
Abstract: The geology of the polar regions of Mars is being remapped using recent topographic, image, and
radar‐sounding data sets from the Mars Global Survey, Mars Odyssey, Mars Express, and Mars
Reconnaissance Orbiter spacecraft. These studies reveal a complex history of ice accumulation at both
poles, starting in the Hesperian Period about 3 billion years ago. Significant episodes of erosion have
resulted in local to regional unconformities in the stratigraphy, which are observed both in image and radar
sounding data sets. Linking the geologic history to the climate history thus far is proving to be difficult.
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6 October, 11:30 ‐ Aula Fuligni, ARTOV
Dr. Bruno Bavassano
ULYSSES: IL TERZO (ED ULTIMO) VIAGGIO AI POLI DEL SOLE
Abstract: Lo scorso 30 giugno la missione Ulysses è giunta al suo termine. Scopo della missione, iniziata
nell'ottobre 1990, era l'esplorazione, con misure in‐situ, dell'eliosfera ad alta latitudine (fino a 80 gradi
dall'equatore solare). In diciannove anni di funzionamento Ulysses ha attraversato le regioni polari
dell'eliosfera tre volte, sotto diverse condizioni di attività solare. Vengono qui presentati alcuni risultati
sulla struttura del vento polare e sulla sua dipendenza dal ciclo del Sole.
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28 September, 11:00 ‐ Aula IBO9, ARTOV
Dr. Jonathan Lunine ( lpl.arizona.edu )
Methane cycles on Titan: From seasonal to geological
Abstract: Cassini and ground‐based data over the electromagnetic spectrum from radio to ultraviolet have
quantified the cycling of methane and its products over various timescales. Seasonal changes include the
development of convective clouds and rainstorms over the summer pole, which dissipate in the late
summer. Evidence for the evaporation of the large lakes in the summer comes from comparing ISS with
radar data of Ontario Lacus. The presence of a strong asymmetry in the number of lakes in one hemisphere
versus the other hints at a longer timescale, perhaps the 50,000 year cycling associated with the precession
of Saturn's orbit, akin to Earth's Croll‐Milankovich cycles. The presence of fluvial features in the presently‐
dry equatorial regions, amidst large‐scale fields of dunes, also suggests a longer‐term oscillation of climate.
Finally, on geologic timescales, there remains the question of the resupply of methane from Titan's interior
to its surface. The outburst of cloud seen from ground‐based telescopes in 2008 might in fact be an
atmospheric expression of a surface geyser pumping crustal methane into the atmosphere.
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17 September, 15:00 ‐ Aula Fuligni, ARTOV
Dr. Michele Pestalozzi (Göteborgs Universitet)
Thermal and Synchrotron radio emission from the X‐ray binary BP Cru
BP Cru is a well known high‐mass X‐ray binary composed of a late B hypergiant (Wray 977) and a neutron
star, also observed as the X‐ray pulsar GX 301‐2. No information about emission from BP Cru in other bands
than X‐rays and optical has been reported to date in the literature, though massive X‐ray binaries
containing black holes can have radio emission from a jet. We searched for radio emission towards BP Cru
using the Australia Compact Array Telescope during a survey for radio emission from Be/X‐ray transients.
We probed the 41.5d orbit of BP Cru not only close to periastron but also close to apastron. BP Cru was
clearly detected in our data on 4, possibly 6, of 12 occasions at 4.8 and 8.6 GHz. Our data suggest that the
spectral index of the radio emission is modulated either by the X‐ray flux or the orbital phase of the system.
In this short seminar I will illustrate our results and present a possible scenario to explain them.
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2 September, 11:00 ‐ Aula Fuligni, ARTOV
Dr. Nelly Mouawad
Ground‐based Observations of Mercury's Sodium Exosphere in conjunction with the first
MESSENGER Flyby
Abstract: The distribution of sodium D2 emission was mapped using the McMath‐Pierce solar telescope
with the 5"x5" image slicer during the period January 10‐18, 2008. Strong temporal and spatial variability of
the sodium emission was observed on the dayside of the planet. On January 14, 2008, the Ultraviolet and
Visible Spectrometer (UVVS) on MESSENGER's Mercury Atmospheric and Surface Composition
Spectrometer (MASCS) sampled the sodium tail region, and captured a single measurement on the dayside
of the planet. I will present results on the hourly and daily variations of the sodium exosphere in
conjunction with results from the First MESSENGER Flyby. The ground‐based data show asymmetries on Jan
12, and shifts in regions of peak emission that might be connected with ion sputtering. It is difficult to
explain the cause of the increase in the total emission on Jan 14 and Jan 15 by photon‐stimulated
desorption (PSD), because the total solar flux in the UV was mostly constant. Even after accounting for the
variations of the interplanetary magnetic field, it is unlikely that the ion sputtering component would have
caused such large variations. This suggests that other physical processes such as ion‐enhanced PSD and/or
impact vaporization might be playing a role in causing these variations. The flux in the Na tail, as seen with
MESSENGER on January 14 th, indicates that the portion of exosphere escaping down the tail constitutes
only a small fraction of the dayside emission.
I will also dedicate part of the talk to present results from the second MESSENGER Flyby, and the
differences between the Mg, Ca and Na exospheric distributions.
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18 June, 11.00 ‐ Aula IB09, ARTOV
Elisabetta Valiante (University of British Columbia ‐ Dept. of Physics and Astr.)
A backward evolution model for infrared surveys: the role of AGN‐ and Color‐L_TIR distributions
Abstract: Empirical ``backward'' galaxy evolution models for infrared bright galaxies are constrained using
multi‐band infrared surveys. I developed a new Monte‐Carlo algorithm for this task, implementing
luminosity dependent distribution functions for the galaxies' infrared spectral energy distributions (SEDs)
and for the AGN contribution, allowing for evolution of these quantities. A local total infrared luminosity
function is adopted and evolved using power law parametrizations for possible luminosity and density
evolution. By assigning an appropriate SED to every source predicted by the model, the algorithm enables
simultaneous comparisons with multiple surveys in a wide range of wavebands. The adopted SEDs take into
account the contributions of both starbursts and AGN to the infrared emission, for the first time in a
coherent treatment rather than invoking separate AGN and star‐forming populations.
In the first part I consider the quantification of the AGN contribution for local universe galaxies, as a
function of total infrared luminosity. It is made using a large sample of LIRGs and ULIRGs for which mid‐
infrared spectra are available in the Spitzer archive. In the second part I present the model. Constrained by
data from the literature, my best‐fit model adopts very strong luminosity evolution and density evolution
for the population of infrared galaxies. At a given total infrared luminosity, high redshift infrared galaxies
have typically smaller AGN contributions to the rest frame mid‐infrared, and colder far‐infrared dust
temperatures than locally. Clues of such evolution have already been obtained in recent photometric and
spectroscopic studies of submillimeter galaxies.
As an example of future applications, we use our best‐fitting model to make predictions for surveys with
Herschel.
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11 June, 11.00 ‐ Aula IB09, ARTOV
Michele Pestalozzi (Göteborgs Universitet Insitutionen för Fysik Göteborg)
What methanol masers can tell you about high‐mass star formation
Abstract: In this talk I will attempt to show that the study of galactic 6.7 and 12.2 GHz methanol masers
themselves, as opposed to the use of methanol masers as signposts, can yield important conclusions
contributing to the understanding of high‐mass star formation. Due to their exclusive association with star
formation, methanol masers are the best tools to do this, and their large number allows to probe the entire
Galaxy. In particular I will focus on the determination of the luminosity function of methanol masers and on
the determination of an unambiguous signature for a circumstellar masing disc seen edge‐on as well as long
time variability, that I will try to connect to the energetics of the maser host. Finally I will try to point out
some future ideas to bridge methanol maser science with Herschel science.
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10 June, 11:00 ‐ Aula Fuligni
S. Savin (Space Research Institute of Russian Academy of Sciences)
Strannik together with magnetospheric multi‐scale (MMS)
A new Russian mission STRANNIK (PILGRIM) on the basis of small mobile satellite is presented in the light
of common measurements with NASA mission Magnetosphere Multi Scale (MMS).
STRANNIK will be launched in late 2014 as a piggyback payload for a geostationary satellite.
Then it will use the plasma electro‐reactive engine to approach the apogee of the MMS orbit in Phase 1
(dayside magnetopause skimming) and thither will follow its apogee till Phase 2 (nightside magnetopause
skimming) end. Thus STRANNIK would be able to add the second scale to MMS, which will do it really multi‐
scale. We discuss the common mission scientific tasks on the basis of Cluster and Interball data, along with
the payload and possible collaboration with IFSI.
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9 June, 11:00 ‐ Aula Fuligni
S. Savin (Space Research Institute of Russian Academy of Sciences)
Alfvénic barriers at the magnetopause and detached from it
Abstract: On the basis of Cluster, Interball data, we discuss the scientific tasks for multi‐scale
measurements in outer magnetosphere, along with the respective strategy for the spacecraft orbits and
ranging.
We concentrate on recently discovered Alfvenic barriers as consequence of turnover of the magnetic field
lines (Alfvenic collapse), and the barrier inter‐relation with the super‐concentrated plasma jets. We display
extremely disturbed magnetosheath regions ahead of magnetopause, which provide evidence for
unprecedented kinetic energy, being effectively separated from the inner stagnant plasma by the
structured Alfvenic barriers. Surprisingly, the barriers have diffusive character in magnetic field, while there
are superdiffusive in the normal plasma velocity.
We compare the data with modeling of turbulent magnetic interface between the stagnant and streaming
plasmas and propose a certain similarity for the edge plasma behavior in fusion devices.
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16 April 2009, 15:00 ‐ Aula IB09, ARTOV
Dr. Sergio Servidio (Bartol Research Institute, University of Delaware, Newark, Delaware, USA)
Magnetic Reconnection in Two‐Dimensional MagnetohydrodynamicTurbulence
Abstract: Systematic analysis of numerical simulations of two‐dimensional magnetohydrodynamic
turbulence reveals the presence of a large number of X‐type neutral points where magnetic reconnection
occurs.
We examine the statistical properties of this ensemble of reconnection events that are spontaneously
generated by turbulence. The associated reconnection rates are distributed over a wide range of values and
scales with the geometry of the diffusion region. Locally, these events can be described through a variant of
the Sweet‐Parker model, in which the parameters are externally controlled by turbulence. This new
perspective on reconnection is relevant in space and astrophysical contexts, where plasma is generally in a
fully turbulent regime.
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16 April 2009, 15.00 ‐ Aula IFSI "F.Fuligni" ‐ 1° piano Edif.U
Danae Polychroni (John Moores University di Liverpool)
Star Formation in the W3 Giant Molecular Cloud
Abstract: The star formation process is one of the most fundamental questions in Astronomy, as it results in
the Initial Mass Function (IMF) that all galaxy evolution models and stellar population synthesis models
assume.
However, we still don't understand fundamental issues of the star forming process. We present here new
data obtained with HARP‐B on the JCMT as well Spitzer data of the W3 Giant Molecular Cloud. We use this
data in conjuction to our older SCUBA and FCRAO data in a multiwavelength study of this molecular cloud,
to better our understanding of the star formation process. We observe, for the first time, a temperature
gradient across the cloud that is clear indication of a time sequence in the observed star forming regions.
We also find IR counterparts to identified SCUBA cores.
We have measured their magnitudes and colours and study the distribution of these stars in the cloud.
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27 Marzo 2009, 14:00 Aula IB09 – Edificio U
Anaelle MAURY (SAp‐CEA, Saclay)
Formation and fragmentation of prestellar cores
Abstract: While most stars are believed to form in multiple systems or in clusters, our present
understanding of the star formation process is still essentially limited to isolated, single dense cores and
protostars. In an effort to gain insight into the processes responsible for core formation and evolution, (e.g.
the origin of the stellar initial mass function), we recently carried out detailed investigations of both the
earliest phases of clustered star formation and the multiplicity of Class 0 objects at small scales.
I'll first present the results of our study investigating the role played by protostellar feedback in clustered
star formation. We carried out an extensive molecular lines mapping of the NGC 2264‐C protocluster, and
quantified the amount of turbulence and support injected by protostellar outflows in the protocluster. I'll
show that even if the population of protostellar outflows identified in NGC 2264‐C is likely to contribute a
significant fraction of the observed turbulence, gravity appears to largely dominate the dynamics of the
NGC 2264‐C clump at the present time.
Then, I'll present the preliminary results of a pilot study imaging 6 Class 0 objects in the 1.2mm dust
continuum, with subarcsecond resolution . These unprecedented observations set constraints on the
multiplicity and fragmentation processes at ~100 AU scales in young protostars observed early after point
mass formation. I'll show that, although most solar‐type pre‐main sequence stars are observed to be in
binary systems with typical separations ?10‐‐300 AU, our sample of Class 0 objects does not show any
multiplicity at ? 50‐2000 AU scales. I'll briefly discuss the direct impact of these observations on binary
formation models.
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19 Marzo 2009, 11:00 Aula IB09 – Edificio U
Luca Calzoletti (INAF‐ASDC)
Near infrared, IFU spectroscopy of HH99
Abstract: I present the first deep near‐infrared (1‐2.5 micron) analysis of a prototype bow shock (HH99B)
performed with the Integral Field Unit spectrograph SINFONI at VLT.
SINFONI offers a new and revolutionary way of studying protostellar shocks, since it is able to sample, at
the same time, the physical conditions occurring along the entire bow shock surface.
The final aim is to provide maps of physical, chemical and kinematical parameters which characterize the
shocked region, through the analysis of bright molecular (H_2) and atomic lines (mainly [FeII]).
From line intensity ratios I have derived density, temperature and extinction along the shock, while from
the profiles of selected lines (e.g. H_2 at 2.12 micron and [FeII] at 1.64 micron) I inferred shock velocity and
geometry. This information has been used to constrain the development of new bi‐dimensional models of
bow shocks.
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16 Marzo 2009, 11:00 Aula IB09 – Edificio U
Dr. Federico Tosi (INAF‐IFSI)
Da Laplace a EJSM: Europa Jupiter System Mission
Abstract: Nel gennaio 1610, le osservazioni telescopiche di Galileo Galilei relative alle lune di Giove
svelarono per la prima volta l'aspetto di un sistema planetario in miniatura. Dopo 400 anni, Europa e Stati
Uniti si apprestano a celebrare questo importante anniversario con una missione congiunta al sistema di
Giove.
Nell'ambito del programma ESA/Cosmic Vision, le due proposte Laplace e Tandem, rivolte all'esplorazione
dei sistemi di Giove e Saturno rispettivamente, avevano superato nel 2007 una prima selezione relativa alle
missioni di classe L. Nel corso del 2008 queste due proposte, ribattezzate rispettivamente "Europa Jupiter
System Mission" (EJSM) e "Titan Saturn System Mission" (TSSM), sono state riviste, ampliate e completate
con l'obiettivo di identificare quale delle avrebbe superato la selezione NASA‐ESA per una missione futura
ai pianeti esterni. Con un comunicato congiunto, le due agenzie spaziali hanno annunciato il 18 febbraio
2009 la selezione della missione EJSM.
Il concetto di EJSM consiste in due elementi primari che operano nell'ambiente di Giove: la sonda Jupiter
Europa Orbiter (JEO), fornita dalla NASA e selezionata come futura missione di classe flagship ai pianeti
esterni, e la sonda Jupiter Ganymede Orbiter (JGO), eventualmente fornita dall'ESA al termine del processo
di selezione di Cosmic Vision. JEO e JGO eseguiranno un'esplorazione sinergica e coordinata del sistema di
Giove prima di inserirsi in orbita attorno ad Europa e Ganimede rispettivamente. I payload delle due sonde
sono stati selezionati per permettere il monitoraggio di fenomeni dinamici (come i vulcani di Io e
l'atmosfera di Giove), la mappatura della magnetosfera gioviana e le sue interazioni con i satelliti galileiani,
e la caratterizzazione degli oceani che con ogni probabilità si estendono sotto le croste ghiacciate di Europa
e Ganimede.
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12 Marzo 2009, 11:00 Aula IB09 – Edificio U
Prof. Michael Mendillo (Boston University)
The Power of Photons: Sodium Exospheres in the Solar System
Abstract: Every object in the solar system has a component of its atmosphere that escapes.
These range from the solar wind to the tenuous tails of comets. Objects without permanent atmospheres
form a class of bodies that have 'Transient Atmospheres" that are continuously being formed and
continuously lost. The Moon and Mercury offer particularly good examples of such surface‐boundary‐
exospheres that can be traced using emissions from sodium gas sputtered from their surfaces.
This seminar will present new results from recent observations of the extraordinarily long tails of sodium
gas propelled by solar radiation pressure at these two bodies.
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28 Gennaio 2009, 11:00 Aula IB09 – Edificio U
Dr. Simonetta Puccetti (Asi Science Data Center ASDC)
Chasing highly obscured AGN in the COSMOS field
Abstract: X‐ray surveys are extremely efficient in selecting unobscured and moderately obscured AGN.
However, they may miss a large fraction of the most obscured AGN (the so called "Compton thick'' AGN),
because both photoelectric absorption and Compton scattering strongly reduce their X‐ray flux. These
objects can be recovered thanks to the reprocessing of the AGN UV emission in the infrared, by selecting
sources with mid‐infrared (and/or radio) AGN luminosities but faint, host galaxy dominated, near‐infrared
and optical emission. Deep multiwavelength surveys from infrared to X‐rays are therefore a unique tool to
complete the AGN census in a wide redshift range. I present here the results of one of these surveys on the
COSMOS field.
I will first introduce the Chandra‐COSMOS survey, and present our multi‐stage source detection process,
studied to optimize both X‐ray source localization and photometry. This allowed us to detect directly most
unobscured and moderately obscured AGN in the field up to z~3‐4. I will then focus on the search for
highly obscured AGN, by selecting Compton thick AGN candidates using Spitzer infrared observations and
validating them by stacking the Chandra data at the position of the infrared selected sources. I will finally
present our evaluation of the Compton thick AGN volume density at z=1‐2 and I will discuss how our results
are able to put constraints on models for the formation and evolution of AGN and galaxies.
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21 Genanio 2009, 10 ‐ ARTOV, Aula IB09
Dr. Belinda Maiolo (Università di Lecce)
" The internal structure of molecular clouds: an observational study "
Abstract: It is intuitively recognized that the star formation process is closely related to the structure of
molecular clouds (MCs). Despite their formation and disruption processes are still debated, turbulence
seems to be the dominating regime in the interstellar medium (ISM) and, in particular, in MCs. One of the
possible consequences of this fluidodynamical regime is the cloud fragmentation required for the
formation of the substructures known as “clumps” and “cores”. More recent observations show that the
ISM is further structured up to the smallest investigated spatial scale, suggesting a fractal description. I shall
focus my attention on the structural analysis of some small MCs (dark globules), by means of optical and
near‐IR imaging, exploiting methods based on both stellar counts and colour excesses. I shall show how
extinction maps, obtained at different wavelengths, can be used to obtain a further, more accurate, visual
extinction map. The behaviour of the total to selective extinction parameter RV will be also discussed.
Particular attention will be given to relationship between the extinction AV and its dispersion sAV that, in
the case of the dark globule CB 52, shows a “parabolic like” behaviour, observed here for the first time
after the theoretical prediction by Lada et al. (1994). The results obtained for this and for other globules
will be discussed in the framework of a simple model suitable for simulating the observed sAV vs. AV
relationships. Also the fractal point of view will be discussed giving insights on the derivation of the fractal
dimension by means of statistical tools as the D‐Variance, the Structure Function and the Autocorrelation
Function. Finally, the 12CO(J=1‐0) integrated intensity maps of some small clouds will be also shown, and
their use as distance estimators will be discussed on the basis of the Heyer & Brunt (2004) notable relation
between velocity dispersion and physical size.
2008 Seminars at IFSI:
22 Dicembre, ore 10 ‐ ARTOV, Aula IB09
Dr. Massimo De Luca (LERMA, Observatoire de Paris)
A square degree of the galactic plane: a multi‐wavelength look at the Vela Molecular Cloud star formation
Abstract: In this talk I will review the present day knowledge of the star formation occurring in a molecular
cloud located on the Galactic plane, known with the name of Vela Molecular Ridge ‐ Cloud D.
A multi‐wavelength study of this region has pointed out a high efficiency in producing both low‐ and
intermediate‐mass stars, both in isolation and in clusters.
In order to characterize the cloud's young population, I will present answers to some important questions
concerning: the correlation between young star distribution and large scale cloud properties, the
classification in mass and age of the proto‐stars, the individuation of the earliest objects and the
description of their mass loss phenomena.
A particular attention will be paid to the description of the methods used to deal with the relatively large
database and to root out and connect information spread over wide wavelength and spatial ranges.
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16 Dicembre 2008 ‐ Ore 15:00 Aula IB09 – Edificio U
Dr. Francesca Civano (Post‐doc at the Harvard Smithsonian Center for Astrophysics)
Multiwavelength properties of C‐COSMOS X‐ray Sources
Abstract: The C‐COSMOS survey is a 1.8 Ms Chandra program to image the center of the COSMOS field to a
depth of 2e‐16 cgs (0.5‐ 7 keV). Adding the Chandra coverage to the COSMOS survey allows us to address
several of the issues concerning the co‐evolution of SMBH and their host galaxies and to fully characterize
the SED of faint AGNs and starburst galaxies not detected in the XMM‐COSMOS survey. I will give a brief
introduction on the COSMOS survey and then I will present the optical identifications of the brighter C‐
COSMOS X‐ray sources, down to a flux limit of 5x10‐16 (cgs) in the 0.5‐7 keV band.
The multiwavelength properties of these sources can be determined by fully exploiting the unique COSMOS
multiwavelength dataset (including HST, Spitzer, multiband optical and near‐IR photometry, and deep
IMACS and VLT optical spectroscopy).
Moreover, I will focus on a few examples of the most interesting classes of objects (obscured AGN, close
pairs, off‐nuclear sources).
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15 Dicembre 2008 ‐ Ore 15:00 Aula IB09 – Edificio U
Dr. Eugenio Schisano (Osservatorio Astronomico di Capodimonte)
Dischi circumstellari attorno a stelle giovani di tipo solare
Abstract: I dischi circumstellari attorno alle stelle giovani sono parte integrante del processo di formazione
stellare e sono il luogo dove si formano i pianeti. La caratterizzazione delle distribuzioni spettrali di energia
è al momento lo strumento più affidabile per studiare la struttura e l'evoluzione della della polvere nel
disco. Si sono identificate, in tal modo, stelle giovani di tipo solare circondate da dischi, detti di transizione,
in cui sono in atto processi dissipativi della componente di polvere, quali, probabilmente, la formazione
planetaria. D'altra parte non si può trascurare la componente gassosa del disco, la cui interazione col il
flusso di radiazione UV ed X dalla stella è in grado di alterare la struttura, la chimica, e l'evoluzione del
disco, avendo effetto sulla dinamica della polvere e anche la formazione dei pianeti giganti. In questo
seminario introdurrò alla problematica dei dischi circumstellari attorno stelle giovani di tipo solare,
soffermandomi sull'argomento dei dischi di transizione mostrando un esempio da me studiato tramite dati
fotometrici e spettroscopici.
Infine introdurrò alla componente gassosa dei dischi, discutendo della necessità di predirre i flussi di alcune
righe di emissione prodotte dall'interazione del gas con un campo di radiazione X fotoionizzante quale utile
confronto con le osservazioni disponibili e future.
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11 novembre, ore 11 Aula IB09
Silvia Leurini ESO
The formation of massive stars: the case study of G351.78‐0.54
Abstract: Despite their importance, our current understanding of the formation of high mass stars remains
very schematic. In this talk, I will briefly review our knowledge of the massive star formation process and
the evolutionary sequence proposed for high‐mass star forming cores with emphasis to the very early
evolutionary phases. As a case study, I will present observations of the southern region G351.78‐0.54,
which we intensively studied in the last year at mm and IR wavelengths. The region shows signs of on going
massive star formation towards a bright IRAS source, which lies at the edge of a dust filament seen in
absorption in the mid IR. I will present a preliminary analysis of this large scale structure in the dust
continumm emission and in molecular emission (CO isotopologues and N2H+), which suggest that the
filament may host several sites of massive star formation in different evolutionary phases.
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05 Novembre 2008 ‐ Aula Fuligni
Dr. S. Savin (IKI, Accademia russa delle scienze)
Comparison of boundary plasma turbulence near magnetopause and in fusion devices
Abstract: A comparative study of fluctuation features in edge plasma of fusion devices and in turbulent
boundary layers of the Earth's magnetosphere have demonstrated similar statistical characteristics
including scalings of structure functions and multifractal spectra. The detected intermittency and
anomalous transport of mass and momentum is carried by sporadic plasma flux bursts with non‐Gaussian
probability of flux magnitude.
The experimental scalings of the structure functions are rather well fitted by the log‐ Poisson model
considering quasi‐1D singular dissipative structures. The plasma scalings display universal properties of
intermittent turbulence. A statistical approach permits to evaluate turbulent transport scalings with time
exponent alpha=1.87 > 1.
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05 Novembre 2008 ‐ Aula Fuligni
Dr. S. Savin (IKI, Accademia russa delle scienze)
Superdiffusion at magnetospheric boundaries
Abstract: On the basis of Cluster, Interball and Geotail observations in the MSH we provide evidence for the
temporary existence of superdiffusion both close to the BS and near the MP. Disturbed zones are similar to
high‐latitude MSH near the MP, known as the "turbulent boundary layer", which is the result of the
interaction of the MSH flow with the throat of the cusp. In both these disturbed zones field and plasma
fluctuations have comparable intensity and similar spectral properties.
Determination of the structure functions of the magnetic field and ion flux also reveals similar multifractal
and intermittent properties. Estimates of the time scaling for the diffusion coefficient in the highly
fluctuating regions yield strong indications for the presence of superdiffusion.
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30 ottobre 2008‐Aula Fuligni
Dr. S. Savin IKI, Accademia russa delle scienze
Future Russian magnetospheric missions in view of European collaboration
Abstract: The seminar will describe three future russian missions (Resonance, Strannik and Roy) devoted to
the study of the Earth's magnetosphere and its interaction with the solar wind, which are scheduled to be
launched starting from 2012. The seminar is specifically targeted to address possible future collaborations
with other European partners and, in particular, with IFSI.
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16 ottobre 2008 ‐ Aula IB09 Edificio U
Edward W. Cliver (Space Vehicles Directorate, Air Force Research Laboratory, Hanscom, Bedford ‐ USA)
History of Research on Solar Energetic Particle (SEP) Events: The Evolving Paradigm
Abstract: Forbush initiated research on solar energetic particle (SEP) events in 1946 when he reported
ionization chamber observations of the first three ground level events (GLEs). The next key development
was the neutron monitor observation of the GLE of 23 February 1956. Meyer, Parker and Simpson
attributed this high‐energy SEP event to a short time‐scale process associated with a solar flare and
ascribed the much longer duration of the particle event to scattering in the interplanetary medium. Thus
"flare particle" acceleration became the initial paradigm for SEP acceleration at the Sun. An more fully‐
developed picture was presented by the Australian radio astronomers Wild, Smerd, and Weiss in 1963.
They identified two distinct SEP acceleration processes in flares: (1) the first phase accelerated primarily ~
100 keV electrons that gave rise to fast‐drift type III emission as the moved outward through the solar
atmosphere; (2) the second phase was produced by an outward moving (~1000 km s‐1)
magnetohydrodynamic shock. This second phase, manifested by slow‐drift metric type II emission,
appeared to be required for the acceleration of ions and higher‐energy electrons. This two‐stage (or two‐
class) picture gained acceptance during the 1980s as composition and charge state measurements
strengthened the evidence for two distinct types of particle events which were termed impulsive
(attributed to flare‐resident acceleration process(es)) and gradual (shock‐associated). Reames championed
the two‐class picture and it is the commonly accepted paradigm today. A key error made in the
establishment of this paradigm was revealed in the late 1990s by observations of SEP composition and
charge states at higher energies (> 10 MeV) than previously available. Specifically, some large and
therefore presumably "gradual" SEP events looked "impulsive" at these energies. One group of esearchers
attributed these unusual events to acceleration of high‐energy SEPs by flares and another chool favors
acceleration of flare seed particles by quasi‐perpendicular shocks. A revised SEP classification scheme is
proposed to accommodate the new observations and to incorporate ideas on geometry and seed particle
composition recently incorporated into models of shock acceleration of SEPs.
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29 sttembre 2008 ‐ Aula IB09 Edificio U
Filomena Cocchia (Osservatorio di Monteporzio)
AMAZE: The evolution of the mass‐metallicity relation at z > 3
Abstract: I will present initial results from AMAZE, an ESO‐VLT large programme aimed at determining the
evolution of the mass‐metallicity relation in the redshift range 3 < z < 5 through observations performed
with SINFONI, the near‐IR integral field spectrometer at VLT.
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18 settembre 2008 ‐ Aula IB09 Edificio U
Alain NOULLEZ (Observatoire de la Cote d'Azur, FRANCE)
THE TURBULENT ENERGY CASCADE IN THE SOLAR WIND
Abstract: Even after the first observations by the Mariner probe of a Kolmogorov‐type power spectrum for
the magnetic fluctuations, direct evidence or other proofs for fluid‐like turbulence in the solar wind have
been missing. One of the only rigorous results for turbulence is the so‐called "‐4/5" Kolmogorov law for the
third‐order moment of the velocity fluctuations, which is a direct signature of the dissipation and of the
time irreversibility in fluid flows. This relation had however not yet been observed or generalized to the
case of turbulence in magnetized fluids like the solar wind.
In this talk, I will first present a phenomenological derivation of the Kolmogorov law and how it can be
derived rigorously, before discussing its physical implications. I will then show how it can be extended for
the case of magneto‐hydrodynamic turbulence, in the form of Yaglom‐type relations that embody all
components of the velocity and of the magnetic field. We have recently verified these relations in the fast
solar wind using high solar latitude measurements obtained by the Ulysses spacecraft. This observation is
particularly important because it provides for the first time a direct estimation of the turbulent energy
transfer rate and dissipation, and we show that the latter can contribute significantly to the in situ heating
of the wind.
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15 settembre 2008 ‐ Aula IB09 Edificio U
Francesco Fontani (ISDC ‐ Observatoire de Genève, Switzerland)
The early lives of high‐mass stars: search for massive pre‐ and proto‐stellar objects
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25 luglio 2008 ‐ Aula IB09 Edificio U
Prof. Jonathan Lunine (Lunar and Planetary Laboratory The University of Arizona)
Titan: The great questions after Cassini‐Huygens
Abstract: Cassini‐Huygens has finished its prime mission and is moving into a two‐year extended
exploration of Titan and the rest of the Saturn system. At this key juncture in the mission's history I will
review what we have learned of Titan and why it deserves to be a primary target for the next stage of outer
solar system exploration.
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22 luglio 2008 ore 11.00 Aula IB09
Paulina Wolkenberg (IFSI/INAF)
"Thermal structure of Martian atmosphere over three volcanoes of Tharsis from selectedmeasurements of
PFS‐MEX"
Abstract: The distribution of atmospheric temperatures and composition are essential elements in the
description of the current state of an atmosphere. Vertical temperature profiles account for the basis for
further interpretations and a description of atmospheric circulations. Tharsis region is the most interesting
area on Mars because of its various topography and an atmospheric response for this topography. I would
like to present my results of my PhD thesis about atmospheric temperatures over three volcanoes: Pavonis
Mons, Arsia Mons and Alba Patera retrieved from Planetary Fourier Spectrometer (PFS) measurements.
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3 luglio 2008 ‐ Aula IB09 Edificio U
Dott. Giuseppe Mitri (Jet Propulsion Laboratory California Institute of Technology)
Titan's Surface and Interior
ABSTRACT: Remote sensing observations yield evidence for compressional tectonism,
resurfacing/cryovolcanism and hydrocarbon lakes on Titan. I will review the diversity of geologic features
revealed using Cassini Titan Radar Mapper and their context. Through theoretical modeling, we are now
starting to understand the geological processes and the interior structure of this enigmatic icy satellite.
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16 giugno 2008 ‐ Aula Fuligni
Prof. S. M. Krimigis (Johns Hopkins Applied Physics Laboratory; and Academy of Athens, Chair of Science of
Space, Athens, Greece)
ENA Observed in the Saturnian Environment by CASSINI/MIMI
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13 giugno 2008‐ Aula IB09 Edificio U
Daniele Fulvio Università di Catania / INAF ‐ OACT
CARATTERISTICHE FOTOMETRICHE E SPETTRALI DELL'ASTEROIDE 4 VESTA E CONFRONTO CON LE
METEORITI HED ESPOSTE AD IRRAGGIAMENTO IONICO
Abstract: Verranno discusse recenti osservazioni fotoelettriche e spettroscopiche dell'asteroide 4 Vesta
nonché i risultati di esperimenti di laboratorio sulle variazioni, a seguito di irraggiamento ionico, delle
proprietà spettrali delle meteoriti Howarditi, Eucriti e Diogeniti, ritenute essere suoi frammenti. I risultati
fotoelettrici verranno analizzati alla luce dell'eterogeneità superficiale di 4 Vesta. Gli esperimenti di
irraggiamento ionico, finalizzati allo studio dei processi di space weathering sui corpi minori del Sistema
Solare, hanno evidenziato arrossamento ed oscuramento degli spettri di tali meteoriti. Le alterazioni
spettrali osservate sono simili a quelle ottenute in analoghi esperimenti di irraggiamento ionico condotti su
olivine e pirosseni terrestri.
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7 Maggio 2008‐ Aula Convegni
Prof. Paul Goldsmith (JPL/Caltech, Pasadena)
Large Scale Structure of the Taurus Molecular Cloud Probed with High Spatial Dynamic Range Spectral Line
Mapping
Abstract: The importance of star formation has led to many instrumental advances, major observational
efforts, and significant progress in understanding the small‐scale structures from which stars form. These
dense cores contain only a small fraction of the mass of the molecular clouds within which they are
embedded, and studies suggest that the rate of star formation is primarily controlled by the rate at which
molecular clouds are formed and at which gas passes from low to high density, with the latter situation
leading to gravitational collapse on a rapid timescale. To understand the earlier phases leading to star
formation, we have obtained fully sampled maps in 12CO and 13CO of the Taurus Molecular Cloud, one of
the nearest and best studied star forming regions. The maps each contain ~3 million spectra and thus have
unprecedented spatial dynamic range, which lets us see a broad range of structures and kinematic features
connecting large and small scales over a factor of 1000 in size. We have used this data to study in detail the
column density distribution, and have determined the total mass of the region to be ~20,000 solar masses,
almost a factor of 3 larger than previously obtained. This is a result of the presence of large amounts of low
column density gas in which the CO abundance is considerably less than generally assumed. The resulting
star formation efficiency (stellar mass/total mass) is thus reduced to between 0.3 and 1.2 percent. We also
briefly touch on the kinematics of the gas and relationship to the magnetic field in the region.
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04 aprile 2008 ‐ Aula Fuligni
Dr. Federico Tosi (IFSI/INAF)
Metodi statistici applicati a dati multisensore e data fusion in missioni planetarie
Abstract: In this work we show two examples of a multivariate statistical method, and data fusion, applied
on data from different instruments onboard the Cassini Orbiter spacecraft.
On Phoebe, we have classified the spectra measured by Cassini/VIMS in order to look for homogeneous
taxonomic units in the multivariate space of the samples, on the basis of the infrared range explored by the
instrument. Such data are superimposed to simultaneous images acquired by the ISS/Narrow Angle Camera
in order to map the identified spectral units on the surface of the satellite.
On Titan, we have searched through Cassini/VIMS hyperspectral cubes, selecting those data which have
convenient viewing geometry and which overlap with Cassini/RADAR footprints having comparable ground
resolution, in order to properly look for correlations between the infrared and microwave ranges explored
by the two instruments. The results, evaluated for the first time through a multivariate statistical method,
can provide constraints on the geophysical models under development for the Titan surface.
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13 Marzo 2008 ore 14:30 ‐ Aula IB09 Edificio U
Marco Delbò (Observatoire de la Côte d'Azur in Nice, France)
L'analisi del calore degli asteroidi: modelli termici e nuove tecniche d'osservazione
Abstract: Presenterò i piu' recenti risultatati nell'ambito della caratterizzazione fisica degli asteroidi ed in
particolare degli asteroidi di tipo "near‐Earth" e "potenzialmente pericolosi", quegli oggetti cioe' che hanno
una probabilità, seppur piccola, di impattare il nostro pianeta. Vi descriverò quali sono le tecniche e gli
strumenti più efficaci per la determinazione delle dimensioni e forme di questi oggetti e come possiamo
studiare le proprietà termiche delle loro superfici mediante l'uso di modelli termici applicati alle
osservazioni nell'infrarosso termico. La conoscenza delle proprietà termiche superficiali e' estremamente
importante per un calcolo accurato della probabilità d'impatto con la Terra degli asteroidi potenzialmente
pericolosi. L'evoluzione orbitale di questi oggetti e' infatti modificata dalla radiazione termica che questi
emettono (effetto Yarkovsky). Per concludere, discuterò gli sviluppi futuri e le prospettive di queste
ricerche in vista dei dati che otterremo grazie a missioni spaziali come Dawn, Marco Polo, Gaia, JWST, WISE
ed Herschel. Vi mostrerò, infine, qualche applicazione particolare dei modelli termici come l'analisi di dati
interferometrici nell'infrarosso termico (VLTI‐MIDI) e lo studio delle eclissi dei satelliti di Urano.
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14 Febbraio 2008 ore 11:00 ‐ Aula IFSI, Edificio U, I° piano
Dr. Iannis DANDOURAS CESR ‐ Toulouse, FRANCE
Titan's exosphere and its interaction with Saturn's magnetosphere: ENA observations and modeling
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6 Febbraio 2008 ore 14:00 ‐ Aula IFSI ‐ Edificio U, I° piano
Dr. Alessandro Mura INAF‐IFSI
Simulation and Observation of the Hermean Sodium Exosphere
2007 Seminars at IFSI
19 Dicembre ‐ Jonathan Lunine (Lunar and Planetary Lab ‐ Tucson, AZ ‐ USA)
Worlds Beyond: A strategy for discovering Earths beyond the solar system
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18 Dicembre ‐ Andrea Boattini, Lunar and Planetary Laboratory, University of Arizona, Tucson, USA
A long journey: from the orbit of Neptune to the Oort cloud
After the discovery of the first trans neptunian object in 1992, the scientific community has started to shed
light on a vast region at the perifery of the solar system. The vision of a solar system ending abruptly
beyond the orbit of Neptune/Pluto has been replaced with an almost continuum of objects spreading until
the immense Oort cloud whose diameter is comparable to one light year. The recent discoveries of a few
Pluto size objects show that there is still a lot to uncover in our neighbourhood.
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21 Novembre ‐ Dr. Thomas B. McCord
The composition of Titan's surface using the Cassini VIMS spectrophotometric data
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8 Ottobre‐ Caitlin Griffith (University of Arizona)
Rain and the formation of washes on Titan's surface
Abstract: The Huygens / Cassini Mission reveals that fluvial washes carve much of the equatorial landscape.
Yet no lakes have been detected in the tropics (only at high northern (and possibly southern) latitudes. In
addition only a few small clouds have been detected over the past 3 years between 30 N and 30 S latitudes.
Albeit, the DISR instrument on Huygens detected a cloud at 21 km altitude.
Two analyses of Titan's temperature profile at the Huygens landing site [1,2] indicate that the atmosphere
is highly stable against convection, and thus rainfall is unlikely. Yet these two studies differ significantly in
their derivation of the stability of the atmosphere. (Barth et al calculate a CAPE of 60 J/kg; however Tokano
et al. calculate a CAPE of 960 K/kg.) Here I investigate the stability of the atmosphere in more detail. I find
evidence for a weak middle tropospheric convection cell that provides an explanation for the presence of
the cloud detected by DISR. In addition, rainfall is unlikely and the atmosphere is indeed highly stable
consistent with Barth's analysis. I then explore different possible methods for producing the rain needed to
create washes in Titan's tropics.
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8 Ottobre ‐ Roger Yelle (University of Arizona)
Nitrogen‐bearing Molecules in Titan's Atmosphere
Cassini observations of Titan's upper atmosphere reveal the presence of an extraordinarily complex
composition. Approximately, 30 molecular species have been detected or inferred from observations. Of
particular interest are the numerous N‐bearing molecules, the most abundance of which (outside of N2) is
HCN. These molecules are important precursors to synthesis of more complex molecules and aerosols and
play an important role in the energy balance of the upper atmosphere. Observations suggest that there
abundance vary strongly with altitude and possibly latitude, in response to the chemical sources and sinks
that control their distribution.
I will present a short summary of the current state of investigations into the distribution of these species
and the important role they play in the overall structure of Titan's atmosphere.
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26 Settembre ‐ W. H. Matthaeus Bartol Research Institute, University of Delaware, Sharp Laboratory
Newark
Turbulence model for heating the solar corona and accelerating the fast solar wind
Abstract ‐ Low frequency waves can be generated by convective photospheric motions and propagate with
some absorption into the lower solar corona.
Here, interacting with Alfven speed gradients, fluctuations of the downward propagating type can be
produced, thus exciting strong MHD turbulence activity. This scenario is explored with various models that
show its feasibility as a heating mechanism for the open field line corona. Finally recent work on a self
consistent model (with M. Velli
and A. Verdini) for accelerating the fast wind, based on the same heating mechanism, is reviewed.
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24 Settembre ‐ W. H. Matthaeus Bartol Research Institute, University of Delaware, Sharp Laboratory
Newark
Correlation, Anisotropy and Structure in solar wind turbulence
Abstract ‐ We discuss theoretical issues pertaining to the formation of transverse complex structure in the
turbulent solar wind plasma.Implications for interpretation of magnetic field data, and for transport of
energetic particles are emphasized, with supporting observational analyses.
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19 Settembre ‐ Andrey Samsonov St. Petersburg State University, Russia
Interaction of an interplanetary shock with the Earth's magnetosphere: results of numerical MHD modelling
The interaction of an interplanetary (IP) shock with the magnetosphere follows several particular phases,
including the interaction of the IP shock with the bow shock, the interaction of the IP shock with the
magnetopause, the transmission of the IP shock into the magnetosphere as a fast mode wave,
modifications of the field‐aligned and ionospheric current systems, and magnetic disturbances observed on
the ground. The interaction of the IP shock with the bow shock and magnetopause was studied previously
using the Rankine‐Hugoniot relations. In our work, we have used results of global and local numerical MHD
modeling to study the dynamics of the interaction. In particular, we find that new discontinuities may
appear in the magnetosheath after the interaction between the IP shock and the bow shock. The IP shock
would reflect inside the magnetosphere, the reflected fast reversed shock may reach the bow shock, and as
a result a sunward motion of the magnetopause and bow shock follows an earthward motion.
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18 Settembre 2007‐ Jeremie Lasue
Aggregation and Thermal Evolution of Comet Nuclei
Author:Jeremie Lasue, A. Coradini, A. C. Levasseur‐Regourd, R. Botet,M. C. De Sanctis, M. T. Capria, G.
Magni, D. Turrini
Comet nuclei are considered as the most pristine bodies of the Solar System. Their study consequently
sheds an important light on the processes occurring during the initial stages of the solar system formation.
Simulations have been developed in our teams to describe new aspects of comet formation and evolution.
Particle aggregation simulations taking into account age‐related cohesive energy of cometesimals during
accretions in the Kuiper belt can be used to interpret the layered structure and surface features observed
for comet 9P/Tempel 1 and quantify the tensile strengths of these objects. Thermal evolution models of
comet nuclei have been rather successful in explaining global aspects of comet observations . A new quasi‐
3D approach for non‐spherically shaped comet nuclei has been developed to analyse the effect of the
irregular shapes (non‐spherical shapes, mountain‐like
and crater‐like features) of comet nuclei on their thermal evolution, on the local crust formation and the
onset of their activity. Our simulations suggest that depressions on the surface play a role in the internal
stratification of the nucleus and can disappear in a comet's lifetime. New simulations specifically designed
for the orbital history and irregular shape of 67P/Churyumov‐Gerasimenko will be presented.
These tensile strength indications and activity predictions will provide vital clues for the international
Rosetta mission rendezvous that will provide further constraints on the formation and evolution processes
of comets.
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30 Luglio ‐ J. Lunine (Lunar and Planetary Lab ‐ Tucson, AZ ‐ USA)
Titano: Dove è andato l'etano?
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16 Luglio 2007‐ D.G. Baishev
Electric Field and Undulations in the Evening Diffuse Auroral Zone
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22 Giugno 2007 ‐ Giuseppe Mitri (Jet Propulsion Laboratory, California Institute of Technology)
Thermal Convection in Ice‐I Shells of Titan and Enceladus
Cassini‐Huygens observations have shown that Titan and Enceladus are geologically active icy satellites.
Mitri and Showman [2005] and McKinnon [2006] have shown that the transition between conductive state
to convective state determine a radical change of the ice‐I shell thermal state with outstanding implications
for the surface structures formation and geology. We explore the thermal state of Titan and Enceladus ice‐I
shells, and also we investigate the consequences of the ice‐I shell conductive‐convective switch for the
geology.
We show that thermal convection can occur, under a range of conditions, in the ice‐I shells of Titan and
Enceladus. Because the Rayleigh number Ra scales with , where d is the thickness of the ice shell and hb is
the viscosity at the base of the ice‐I shell, and because ammonia in the liquid layer (if any is present)
strongly depresses the melting temperature of the ice water, Ra equals its critical value for two ice‐I shell
thicknesses: for relatively thin ice shell with warm, low‐viscosity base (Onset I) and for thick ice shell with
cold, high‐viscosity base (Onset II). We demonstrate that the Onset I of Enceladus ice‐I shell enlarging upon
an ocean produces tectonic stress of ~500 bars, and fractures of several tens of km depth. We show also
that the cooling and refreezing of Titan’s outer liquid layer produce radial expansion of the ice‐I layer and a
larger radial contraction of the ice high pressure layer. Therefore as consequence of Titan’s cooling, a global
contraction could occur. We demonstrate also that at Onset II, Titan’s and Enceladus’ ice‐I shell experiences
oscillations in the surface heat flux with periods of ~50‐800 Myr even when the interior heat production is
constant or monotonically declining in time; these oscillations in the thermal state of the ice‐I shell could
cause repeated episodes of extensional and compressional tectonism.
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29 Maggio 2007 Carlo di Lauro ‐ Università di Napoli Federico II
Spettri vibro‐rotazionali ad alta risoluzione: l'etano.
Vengono brevemente illustrati i meccanismi di formazione di serie caratteristiche di righe nelle bande
vibro‐rotazionali parallele e perpendicolari di molecole aventi due momenti d’inerzia uguali tra di loro,
come l’etano. La meccanica delle deformazioni perpendicolari all’asse di simmetria è complicata dalle forze
di Coriolis quando la molecola ruota intorno a detto asse.
Viene quindi esaminato lo spettro vibro‐rotazionale dell’etano con particolare riferimento alle regioni
spettrali intorno a 1450 cm‐1 (6.9 m) e 3250 cm‐1 (3.1 m), dando risalto alle caratteristiche seguenti:
1‐ Effetti della rotazione dei due gruppi coassiali CH3 l’uno rispetto all’altro.
2‐ Perturbazioni vibro‐roto‐torsionali ed informazioni che si possono possono trarre da esse.
3‐ Effetti della temperatura.
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21 Maggio 2007 ‐ Christina Plainaki Dip. di Fisica Università di Atene (Grecia)
Modeling ground level enhancements of solar cosmic rays
Solar cosmic rays can effectively be used for studying the processes of particle acceleration in the solar
atmosphere and their propagation in interplanetary space, as well as for understanding the
electromagnetic conditions at the Sun. On rare occasions a solar flare will accelerate protons to sufficiently
high energies for these particles to propagate along the heliomagnetic field to the earth and be detected as
a sharp increase in the counting rate of a ground based cosmic ray detector causing a Ground Level
Enhancement of solar cosmic rays (GLE). The NM‐BANGLE model is a new cosmic ray model which couples
primary solar cosmic rays at the top of the Earth's atmosphere with the secondary ones detected at ground
level by neutron monitors during GLEs. This model calculates the evolution of several GLE parameters such
as the solar cosmic ray spectrum and anisotropy as well as the particle flux distribution, revealing crucial
information on the solar cosmic ray particle propagation and distribution. As an input the NM‐BANGLE
model uses cosmic ray GLE data from neutron monitor stations widely distributed around the world.
Moreover, it takes into account the geomagnetic activity at some specific moment and uses as an
additional input the calculations of energetic particle trajectories inside the Earth’s magnetic field, which
has been represented according to Tsyganenko‐1989 model. The total output of the NM‐BANGLE model is a
multi‐dimensional GLE picture that gives an important contribution to understanding the physics of solar
cosmic ray particles under extreme solar conditions. The event of 20 January, 2005 (GLE 69) associated with
an X7.1 class solar flare, has been one of the biggest enhancements observed by the ground level neutron
monitors. Application of the NM‐BANGLE model to GLE 69 revealed that the first solar particles entered the
atmosphere of the earth forming a narrow beam originating from southern hemisphere. The integral
primary proton spectrum during the first time intervals of the event was rather complicated suggesting
different kind of possible acceleration and propagation scenarios. Several parameters of these primary
solar particles, such as the position of the anisotropy source and its time evolutions, are obtained and
discussed.
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17 Maggio 2007‐ Federica Marcucci ‐ INAF/IFSI
La missione Cross‐Scale: importanza delle misure multiscala dei plasmi spaziali
Le onde d’urto, la riconnessione magnetica e la turbolenza sono fenomeni fondamentali per la fisica dei
plasmi nell’Universo. Questi fenomeni sono caratterizzati da variabilità e strutture tridimensionali che si
manifestano su un grande intervallo di scale, in particolare: la scala degli elettroni, la scala degli ioni e la
scala fluida (MHD). La comprensione di tali fenomeni, quindi, richiede necessariamente la conoscenza di
come avviene l’interazione fra processi che si verificano contemporaneamente a queste tre diverse scale.
Tutti i fenomeni menzionati possono essere osservati nello spazio vicino alla Terra. Una missione, Cross‐
Scale, comprendente una flotta di tre gruppi di satelliti, con i singoli gruppi contenenti fino a 4 satelliti con
una distanza di separazione confrontabile con la scala degli elettroni, degli ioni e fluida, fornirebbe misure
in situ tridimensionali e simultanee a queste tre diverse scale e apporterebbe un avanzamento significativo
nella conoscenza della fisica dei plasmi.
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11 Maggio 2007‐ Consuelo Cid Tortuero (University of Alcalà, Alcalà de Henares, Spain)
Forecasting Intense Geomagnetic Activity
Southward interplanetary magnetic fields, resulting from magnetic reconnection of solar wind and
magnetosphere, are considered traces of geoeffectiveness. We present a statistical analysis concerning the
role played by this interplanetary feature in the solar wind‐magnetosphere coupling during intense
geomagnetic activity. Other equivalent signatures such as duskward electric fields were also shown. The
studies were performed using the OMNIweb database, and the results obtained, with about 50% of hits,
guided us in looking for other features in the solar wind that could be considered signs of intense activity.
Large variations of Bz, considered as a trigger of intense geomagnetic activity, allowed us to forecast 100%
of the events where variation of Dst index was less than ‐75 nT per hour.
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Lunedì 12 gennaio 2007 ‐ Dr. Monio Kartalev Institute of Mechanics Bulgarian Academy of Sciences Sofia
Modelling of the global ionospheric electric potential
2006 Seminars at IFSI
20 dicembre 2006 ‐ Alan Stern
"The New Horizons Mission: A First Reconnaissance of the Sun's Third Zone"
The New Horizons spacecraft, launched on January 19, 2006 as the first of NASA's New Frontiers line of
medium‐class, PI‐led missions, will be the first spacecraft to encounter the Pluto system and explore the
Kuiper Belt. The close encounter with Pluto, its large moon Charon, and Pluto's two recently discovered
small satellites will take place on July 14, 2015.
En route to Pluto, the New Horizons spacecraft will encounter Jupiter on February 28, 2007 at a distance of
32.2 Jupiter radii, receiving a gravity assist and shortening what would otherwise be a substantially longer
flight time. After the Pluto system encounter, and pending NASA approval, the New Horizons spacecraft
may encounter 1 or 2 smaller (35‐50‐km, or possibly larger diameter) Kuiper Belt objects. I will summarize
the
mission's history and the science background, its science objectives, its instrument payload, and its current
status.
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29 Novembre 2006 ‐ Giuseppe Pallocchia (INAF‐IFSI)
Osservazione di onde d'urto interplanetarie nella magnetosheath terrestre
Quando due onde d’urto magnetoidrodinamiche collidono le relazioni di Rankine‐Hugoniot non sono, in
generale, soddisfatte sulla linea di contatto dei due fronti d’onda. La teoria MHD prevede, quindi, che la
discontinuità che si origina, decada istantaneamente in un “treno” di urti o onde auto‐similari che possono
variare da un numero minimo di tre ad un massimo di sette (quest’ultimo caso corrisponde alla soluzione
generale del problema di Riemann).
Nel seminario verranno presentate e discusse alcune osservazioni, fornite dalle sonde della missione
CLUSTER, relative al passaggio nella magnetosheath terrestre di onde d’urto di origine interplanetaria
trasformate dall’impatto con il bow shock ed accompagnate da onde e discontinuità secondarie prodotte
da quello stesso impatto in (vago) accordo qualitativo con il quadro teorico apppena accennato e con
alcune recenti simulazioni 3D. In ultimo sarà proposto un interessante caso di studio riguardante
l’osservazione, sempre nella magnetosheath, di una discontinuità con caratteristiche molto vicine a quelle
di un’onda d’urto “intermedia” (a questo proposito ricordiamo che gli shock intermedi non sono
evoluzionali e quindi non dovrebbero avere esistenza fisica).
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7 Novembre 2006 ‐ Prof. G. P. Zank (Director, Institute of Geophysics and Planetary Physics, University of
California, Riverside)
Particle Acceleration in Cosmic Plasmas
An outstanding problem in astrophysics is to explain the origin of the almost featureless cosmic ray
spectrum extending up to energies of some 1020 eV. A very small feature is apparent at between about
1013 – 1015 eV, the “knee.” In the late 1970’s, a suite of papers was published establishing the idea of
diffusive shock acceleration for cosmic rays, essentially a first‐order Fermi mechanism, which appeared to
provide an explanation for the observed cosmic ray spectrum up to the knee. Diffusive shock acceleration is
probably the most widely used particle acceleration mechanism in astrophysics and space physics, yet the
theory is based on some stringent simplifications. The detailed [plasma] physics of the acceleration
mechanism requires elucidation. We are fortunate in that very detailed observations of particle
acceleration at shock waves, particularly in the guise of Space Weather, are providing considerable
experimental insight into the basic physics of particle acceleration at a shock wave. Indeed, understanding
the problem of particle acceleration at interplanetary shocks is assuming increasing importance, especially
in the context of understanding the space environment. Detailed interplanetary observations are not easily
interpreted in terms of the simple original models of particle acceleration at shock waves. Three
fundamental aspects make the interplanetary problem much more complicated than the typical
astrophysical problem: the time dependence of the acceleration and the solar wind background; the
geometry of the shock; and the long mean free path for particle transport away from the shock wave. An
interplanetary shock is not steady, as it decelerates and expands into an expanding, temporal solar wind.
Furthermore, the shock geometry varies from quasi‐parallel to quasi‐perpendicular along a shock front, and
multiple shocks can be present simultaneously in the solar wind. Consequently, the shock itself introduces a
multiplicity of time scales, ranging from shock propagation time scales to particle acceleration time scales
at parallel and perpendicular shocks, and many of these time scales feed into other time scales (such as
determining maximum particle energy scalings, escape time scales, etc.). We will discuss the basic physics
of particle acceleration via scalings, their relationship to particle acceleration models, observations and
geometry in both an astrophysical and space physics context. This will include discussing the physics of
perpendicular and parallel shocks, upstream turbulence, particle spectra, and particle injection and the
seed population. After acceleration of particles at an interplanetary shock, the transport of energetic
particles is non‐diffusive because of their large mean free path in the quiet solar wind. The complications of
coupling diffusive (at the shock) to non‐diffusive transport will be addressed. In particular, we will address
the coupled acceleration and transport of heavy ions, Fe/O ratios, the variability among individual events,
and seed particle populations. We will discuss theoretical models and address recent modeling efforts.
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6 Novembre 2006 ‐ Jeremie Lasue (CNRS Service Aeronomie ‐ Verrieres cedex, France / Universite Pierre et
Marie Curie ‐ Paris cedex, France)
Light scattering by irregular aggregates: experimental and numerical simulations, applications to solar
system small bodies
Cometary and interplanetary dust particles are essential witnesses of the formation and evolution of the
solar system. Their physical characteristics can be retrieved from the light they scatter and emit. In this
respect, the polarimetric data (normalized) are particularly interesting to compare these objects at
different orbital positions.
After a brief overview of these themes, the first part of the presentation is dedicated to laboratory
polarimetric measurements. We present the results of an experimental simulation in parabolic flights with
the PROGRA2 experiment (PRopriétés Optiques des GRains Astronomiques et Atmosphériques) to
determine the physical properties of coated micron‐sized particles. We then present the development of
experimental and numerical tools to analyse in terms of phase angles, wavelengths and structure the light
scattered in the visible domain by aggregates built in microgravity. These aggregates analogous to
protoplanetary particles will be formed with the european ICAPS experiment (Interactions in Cosmic and
Atmospheric Particles System) on board the International Space Station.
The second part of our work is dedicated to the modelling of the light scattered by irregular particles typical
of cometary or interplanetary dust. We show that a light scattering model of a cloud constituted of fractal
aggregates of non spherical grains and spheroids can be used to estimate the size distribution and
constituting material from polarimetric observations well documented with the phase angle and the
wavelength from the visible to the infrared. This model is applied in particular to comet
Hale‐Bopp (size distribution following a power law with ‐3 coefficient between 0.1 and 20 (m radii and a
mixture of silicates and organics material) and to the zodiacal cloud near the ecliptic (by modelling also the
thermal emission).
This work shows the complementarity between both approaches ‐ experimental and numerical ‐ to
interpret polarimetric measurements and observations.
This is a first stage to prepare measurements that will be made with ICAPS and the in situ observations that
the cometary probe Rosetta will carry out during its rendezvous with 67P/Churyumov‐Gerasimenko.
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30 Ottobre 2006 ‐A. Retinò Swedish Institute of Space Physics, Uppsala, Sweden
Spacecraft Observations of the Microphysics of Magnetic Reconnection
Magnetic reconnection is a universal process occurring at boundaries separating magnetized plasmas,
where changes in the topology of the magnetic field lead to the conversion of electromagnetic energy into
energy of charged particles. Reconnection is a cross‐scale process, it affects large volumes in space for long
time but is initiated fast in small diffusion regions by microphysical plasma processes. Despite the fact that
reconnection has been studied for decades and is commonly accepted as a dominant process, the details of
its microphysics are not yet understood and in‐situ observations are few. The best laboratory to study the
microphysics of reconnection from an ex‐perimental point of view is the Earth’s geospace, where in‐situ
spacecraft ob‐servations are possible. In particular Cluster spacecraft observations are unique due to the
capability to perform four‐point measurements.
We present spacecraft observations of the microphysics of reconnection in several regions of geospace. At
the dayside magnetopause we show examples of diffusion regions and separatrix regions and discuss their
microphysical proper‐ties. In the magnetosheath we show examples of thin current sheets and discuss their
implications for reconnection in turbulent plasma. In the magnetotail we show observations of small‐scale
magnetic islands and discuss in detail their microphysics.
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24 Ottobre 2006 ‐ Gianrico Filacchione ‐ INAF/IASF
La calibrazione di spettrometri ad immagine VIS‐NIR per l'esplorazione planetaria: Cassini‐VIMS‐V e
Rosetta‐ VIRTIS‐M
Nel corso degli ultimi 15 anni l'esplorazione planetaria ha potuto beneficiare dei dati iperspettrali prodotti
dagli spettrometri ad immagine VIS‐NIR. Grazie a questa nuova classe di strumenti, in grado di coniugare le
capacità di imaging con l'analisi spettrale, è possibile riconoscere le unità composizionali delle superfici
nonchè la composizione e la dinamica delle atmosfere planetarie. Il gruppo di planetologia IASF‐IFSI è stato
in grado di proporre alla comunità scientifica internazionale diversi spettrometri ad immagine dalle elevate
prestazioni che sono stati impiegati a bordo di diverse missioni interplanetarie. Tra questi un ruolo di
primaria importanza stanno avendo VIMS‐V (Visual and Infrared Mapping Spectrometer) a bordo di Cassini
e VIRTIS‐M (Visible and Infrared Thermal Imaging Spectrometer) a bordo di Rosetta. Per questi due
strumenti saranno discusse le attività compiute negli scorsi anni per poterne caratterizzare le risposte
spettrali, spaziali, geometriche e radiometriche sia mediante misure condotte durante i test di pre‐lancio
sia mediante osservazioni di oggetti celesti. Saranno inoltre esposti gli algoritmi di processamento ed analisi
dei dati iperspettrali e le pipeline di calibrazione attualmente in uso nei team scientifici.
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18 Ottobre 2006 ‐Del Bianco S. ‐ Istituto di Fisica Applicata ``Nello Carrara'' del Consiglio Nazionale delle
Ricerche (IFAC‐CNR)
MARC: un codice per l'inversione di misure indirette con onde millimetriche di parametri atmosferici in
presenza di nubi
Il codice MARC (Millimetre‐wave Atmospheric‐Retrieval Code) verrà utilizzato per l'analisi delle misure di
uno strumento eterodina che effettua misure al lembo con onde millimetriche. MARC consente di ricavare
profili in funzione della quota di temperatura e di alcuni composti atmosferici minori nella zona dell'alta
troposfera‐bassa stratosfera. Nella zona millimetrica l'atmosfera può essere trasparente anche in presenza
di nubi; MARC consente di modellare, oltre al trasferimento radiativo in atmosfera, anche l'effetto delle
nubi fornendo così informazioni anche sulle proprietà di quest'ultime.
Le molteplici opzioni del codice e la flessibilità con cui è stato implementato consente di utilizzare lo stesso
codice per diverse geometrie di misura e regioni spettrali.
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18 Ottobre 2006 ‐ Dr. Simone Ceccherini ‐ Istituto di Fisica Applicata "Nello Carrara" del Consiglio Nazionale
delle Ricerche (IFAC‐CNR).
ORM per l'analisi di Livello 2 delle misure di MIPAS/ENVISAT
MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) è un interferometro a trasformata di
Fourier che misura, a bordo del satellite ENVISAT, l'emissione al lembo dell'atmosfera nel medio infrarosso.
Dall'analisi delle sue misure è possibile ricavare i profili verticali della temperatura e della concentrazione di
numerose specie atmosferiche minori ottenendo, ogni giorno, un monitoraggio quasi globale
dell'atmosfera in funzione di latitudine, longitudine e altezza.
L'algoritmo per l'analisi operativa in tempo quasi reale delle misure di MIPAS è stato realizzato da un
consorzio europeo sotto la responsabilità di IFAC‐CNR.
Sarà presentata la strategia del codice di retrieval ed alcuni esempi dei prodotti di Livello 2 di MIPAS.
21 Giugno 2006 ‐ Prof. S.C. Chapman Centre for Fusion, Space and Astrophysics ‐ Univ. of Warwick (UK)
Solar wind turbulence: models and methods
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26 Maggio 2006 ‐ J. Lunine
Dove dovremmo andare nel sistema solare esterno?
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12 Aprile 2006 ‐ J. Lunine and A. Graps
Formation of terrestrial planets and the origin of water on Earth
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12 Aprile 2006 ‐ G Consolini
ANALISI DELLE COMPONENTI PRINCIPALI DEL CICLO DELLE MACCHIE SOLARI
di G.Consolini, R. Tozzi (INGV) and P. De Michelis (INGV)
Lo studio del ciclo dei sunspot solari è ampiamente utilizzato per investigare sia l’attività solare in generale,
che l’attività magnetica. In questo ambito la modellizzazione del ciclo solare rappresenta uno dei punti di
partenza per lo sviluppo di qualunque modello di dinamo solare. In questo lavoro, la tecnica dell’analisi
delle componenti principali (NOC) viene applicata al ciclo delle macchie. I risultati sembrano indicare
l’esistenza di due sottocicli di durata analoga, ma in ritardo di fase l’uno rispetto all’altro di circa 90°. La
presenza di tali sottocicli viene discussa in termini di differenti popolazioni di macchie. Viene, inoltre,
proposto un parallelismo tra il comportamento osservato e quello riscontrabile nel modello evolutivo di
Lotka‐Volterra.00
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27 Marzo 2006 ‐ G Tinetti
Characterizing Extrasolar Planets with Remote Sensing Spectroscopy
In the past decade, over 160 planets orbiting other stars (extrasolar planets) were discovered using indirect
detection techniques. The known sample is constrained by the currently achievable detection techniques,
which are more sensitive to larger worlds.
To extend the detection ability down to Earth‐sized planets, both the European Space Agency (ESA) and
National Aeronautics and Space Administration (NASA) are developing large and technologically challenging
space‐borne observatories.
The first of these missions is due for launch as early as 2015, and will provide our first opportunity to
spectroscopically study the global characteristics of Earth‐like planets beyond our solar system, to search
for signs of habitability and life.
Almost a decade in advance to the launch of ESA‐Darwin or NASA‐Terrestrial Planet Finders, most recent
observations of primary and secondary eclipses with Hubble Space Telescope and Spitzer of transiting
extrasolar giant planets (EGPs), (Charbonneau et al., 2002, 2005; Vidal‐Madjar et al., 2003, 2004; Deming et
al., 2005), suggest that emission and transmission spectra of EGPs can be used to infer many properties of
their atmospheres and internal structure, including chemical element abundances, hydrodynamic escape,
cloud heights, temperature‐pressure profiles, density, composition and evolution.
The next generation of space telescopes (James Webb Space Telescope, JWST) will have the capability of
acquiring more precise spectra in the visible and infrared of these extrasolar worlds. The ultimate extension
of such searches will be to observe the primary and secondary eclipse of Earth‐size planets.
To understand our ability to characterize Giant and Terrestrial exoplanets, we have generated synthetic
planetary spectra (emitted, reflected and transmitted) of these environments, using a set of chemistry,
climate and radiative transfer models.
In this presentation we focus on the detectability of surface biosignatures and spectral signatures of crucial
atmospheric molecules such as water, carbon monoxide and dioxide, methane, oxygen and ozone, over
continuous wavelength ranges that span those being considered for future missions and present
observations.
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1 Marzo 2006 ‐ Jonathan Lunine
Il segreto di Iapeto
In collaborazione con J. Castillo, T. Johnson, D. Matson, P. Thomas, C. Sotin
Cerchiamo di spiegare la forma e la rotazione di Iapeto e per fare questo troviamo dei valori molto specifici
per il tempo di formazione, la composizione, ecc. Descrivero' il modello ed alcune implicazioni in questa
conferenza.
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1 Marzo 2006 ‐ Sylvain Doutè (Laboratoire de Planetologie de Grenoble, CNRS)
A new view of the South seasonal cap of Mars
The high latitudes of Mars are covered by a seasonal CO2 ice deposit. The time and space evolutions of this
cover is a major annual climatic signal both at the global and the regional scales. In particular the
measurement of the temporal and spatial distributions of CO2 constrains many atmospheric and surface
processes involving the latter compound but also H2O and dust. The physical state and texture of the ices
and frosts also represent valuable indicators.
The hyperspectral imaging spectrometer OMEGA on board Mars Express has been scrutinizing the seasonal
changes at the poles of Mars in the near infrared in both hemispheres since it began its operation in early
January 2004.
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13 Febbraio 2006‐ M.B. Cattaneo
Cluster osserva la struttura della magnetopausa molto vicino ad un sito di riconnessione
La missione dell'ESA Cluster è la prima missione magnetosferica costituita da 4 satelliti vicini dedicata allo
studio della microfisica del plasma. Si discuteranno alcuni aspetti del processo di riconnessione magnetica,
ossia del processo di fisica del plasma che cambia la configurazione del campo magnetico e converte
l'energia magnetica in energia cinetica del plasma.
Con i dati dell'esperimento CIS a bordo dei satelliti di Cluster è stato studiato un evento di riconnessione,
analizzandolo sia dal punto di vista
fluido, sia dal punto di vista cinetico. L'evento in questione avviene nella magnetosfera terrestre, alla
magnetopausa di alta latitudine, in condizioni interplanetarie abbastanza stabili, e dura 4 ore. L'analisi degli
ioni accelerati nello strato di corrente ha confermato quantitativamente le previsioni MHD. Inoltre l'avere
misure simultanee in diversi punti di osservazione ha permesso di determinare un limite superiore per la
distanza dei satelliti dal sito di riconnessione: 3200 km. Si tratta di una distanza piccola. E' probabilmente la
vicinanza al sito di riconnessione a far sì che l'analizzatore di plasma osservi nello strato di corrente varie
popolazioni ioniche che attraversano la magnetopausa in entrambi i sensi. Si descriveranno vari tipi di
queste popolazioni e si mostrerà che le loro caratteristiche sono in accordo con un modello cinematico.
Partendo poi dalla analisi dettagliata della funzione di distribuzione di alcune di queste popolazioni si
mostrerà che, durante alcuni brevi intervalli, la riconnessione avviene simultaneamente sia in vicinanza dei
satelliti, sia nell'emisfero opposto, come ipotizzato da alcuni modelli di riconnessione alla magnetopausa
per campo interplanetario diretto verso nord.
Infine, si metteranno in evidenza le grande potenzialità derivanti dall'avere misure simultanee in più punti.
2005 Seminars at IFSI:
20 Dicembre 2005‐ Jonathan Lunine
La storia di Titano
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7 Dicembre 2005 ‐ Roberto Peron
Fisica fondamentale nello spazio: i satelliti LAGEOS
Grazie al crescente sviluppo delle tecnologie spaziali, lo spazio circumterrestre è diventato uno dei luoghi di
elezione per la verifica sperimentale delle teorie della gravitazione (in particolare la geometrodinamica
einsteiniana). Questo continuo lavoro di ricerca ha anche un concreto ritorno applicativo, come dimostra la
tecnologia di navigazione satellitare GPS. Dopo una introduzione generale a queste tematiche, verranno
presentati recenti risultati relativi ai satelliti LAGEOS. Lo studio orbitale di questi satelliti, sviluppati per
applicazioni geofisiche e geodinamiche, permette di effettuare importanti verifiche della teoria di Einstein,
in particolare il ben noto fenomeno del trascinamento dei sistemi inerziali intorno ad un corpo rotante
(effetto Lense‐Thirring). La sua misura verrà illustrata con un certo dettaglio, insieme ad alcuni risultati nel
campo della geofisica.
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25 Novembre 2005 ‐ Dr. Nikolay Ignatiev (IKI Mosca Russia)
Modiying the ARS code. Compilation on different platforms. Parallelization possibilites.
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24 Novembre 2005 ‐ Dr. Nikolay Ignatiev (IKI Mosca Russia)
Study case: computation of a Venus spectrum. Step by step extension of inizialization files, issues and
possible problems to study for the future.
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23 Novembre 2005 ‐ Giuseppe Consolini
Statistica Non‐Gaussiana nei Plasmi Spaziali, un Approccio di Termodinamica del Non‐Equilibrio
Uno degli aspetti più interessanti delle fluttuazioni nei plasmi spaziali risiede nella forma non Gaussiana
delle funzioni di distribuzione di probabilità (PDF) delle fluttuazioni stesse. Questa proprietà delle
fluttuazioni insieme all’evidenza di invarianza di scala ed al carattere turbolento delle fluttuazioni
medesime è stato interpretato come un fenomeno di intermittenza. In passato molti modelli per la natura
non Gaussiana delle fluttuazioni sono stati proposti. Recentemente, Beck e Cohen hanno introdotto il
concetto di “superstatistica” per spiegare l’emergere di distribuzioni non Gaussiane in sistemi fuori
dall’equilibrio, e con correlazioni a lungo raggio. Nel presente intervento, muovendo dall’idea di “sistema
termodinamico composito” ed utilizzando il concetto di “temperatura operativa casuale” viene discusso
uno scenario alternativo per la natura non Gaussiana delle fluttuazioni nei plasmi. Questo approccio è
motivato dai recenti risultati teorici ed osservativi sull’esistenza di strutture magnetiche e di plasma nei
plasmi spaziali. Una nuova forma per le PDF alle piccole scale viene derivata e confrontata con i risultati di
osservazioni in‐situ.
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23 Novembre 2005 ‐ Dr. Nikolay Ignatiev (IKI Mosca Russia)
Multiple scattering treatment of thick atmospheres. Algorithms available in ARS. Issues experienced by
correlated‐I method.
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22 Novembre 2005 ‐ Dr. Nikolay Ignatiev (IKI Mosca Russia)
ARS: different methods for fast evaluation of gaseous opacity. Line by line and intepolation techniques.
Available implementations and step‐by‐step creation of pre‐computed databases.
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21 Novembre 2005 ‐ Dr. Nikolay Ignatiev (IKI Mosca Russia)
Introduction to ARS ‐ yet another version of software for radiative transfer and simulation of spectra of
planetary atmospheres