Astronomy 305/Frontiers in Astronomy

11/4/03 Prof. Lynn Cominsky 1

Class web site: Class web site: http://glast.sonoma.edu/~lynnc/courses/ahttp://glast.sonoma.edu/~lynnc/courses/a305305

Office: Darwin 329A and NASA E/POOffice: Darwin 329A and NASA E/PO

(707) 664-2655(707) 664-2655

Best way to reach me: Best way to reach me: [email protected]@charmian.sonoma.edu

Astronomy 305/Frontiers in Astronomy 305/Frontiers in AstronomyAstronomy


Group 10Group 10


Where are the Sun’s neutrinos?Where are the Sun’s neutrinos?

The SunThe Sun A bit of historyA bit of history PropertiesProperties RegionsRegions

Sub-atomic ParticlesSub-atomic Particles Solar neutrino problemSolar neutrino problem Neutrino oscillationsNeutrino oscillations


The Solar MassThe Solar Mass

History of the changing views of History of the changing views of the Sun’s place in the Universethe Sun’s place in the Universe

Written and produced by Lynda Written and produced by Lynda Williams for the SFSU PlanetariumWilliams for the SFSU Planetarium

Solar.rm

Play real movie


The Sun Song by the ChromaticsThe Sun Song by the Chromatics

Astrocapella videoAstrocapella video


Solar PowerSolar Power The Sun is powered by nuclear fusion The Sun is powered by nuclear fusion

reactions in its corereactions in its core The gravity from the Sun’s mass The gravity from the Sun’s mass

squeezes the nuclei together so that squeezes the nuclei together so that they can overcome electrostatic they can overcome electrostatic repulsion and fuse repulsion and fuse

… but high pressure and temperature encourage

impact

Electrostatic repulsion stops impact


Solar PowerSolar Power Hydrogen nuclei fuse to Deuterium Hydrogen nuclei fuse to Deuterium

and then Helium, releasing about 7 and then Helium, releasing about 7 MeV eachMeV each

The released radiation keeps the Sun The released radiation keeps the Sun from collapsing due to its own gravityfrom collapsing due to its own gravity

Start with 4 protons under enormous

pressure and temperature

End up with a “normal” helium nucleus,

two gamma rays, two positrons and

two neutrinos

Several Reactions


Sun FactsSun Facts Mass of SunMass of Sun 1.989 x 10 1.989 x 103030 kg kg Diameter of SunDiameter of Sun 1,390,000 km 1,390,000 km Distance to Sun Distance to Sun 1 A. U. or 1 A. U. or

93 x 1093 x 1066 miles or ~1.5 x 10 miles or ~1.5 x 101111 m m Rotation Rate of Sun Rotation Rate of Sun 25.4 d (equator)25.4 d (equator)

36 d (poles)36 d (poles) Surface Temperature of SunSurface Temperature of Sun 5800 K 5800 K

(yellow visible light)(yellow visible light)


Sun FactsSun Facts Power from SunPower from Sun 3.86 x 10 3.86 x 1026 26 WW Composition of SunComposition of Sun 75% Hydrogen 75% Hydrogen

25% Helium 25% Helium <0.1% other elements <0.1% other elements

Age of Sun Age of Sun 4.5 billion years …. 4.5 billion years …. with another ~5 billion years to gowith another ~5 billion years to go

Pressure at corePressure at core 2.50 x 10 2.50 x 101111 atm atm Magnetic Field of Sun Magnetic Field of Sun a few Gauss a few Gauss

(average) but up to 10(average) but up to 103.53.5 G connecting G connecting sunspots of opposite polaritysunspots of opposite polarity


Features of the SunFeatures of the Sun


Regions of the SunRegions of the Sun CoreCore – dense region consisting of plasma of – dense region consisting of plasma of

electrons and protons which undergo nuclear electrons and protons which undergo nuclear fusion reactions to power the Sun. fusion reactions to power the Sun. Temperature is greater than 15,000,000 K.Temperature is greater than 15,000,000 K.

Radiation zoneRadiation zone – region containing both – region containing both plasma and atoms. The atoms slowly (170,000 plasma and atoms. The atoms slowly (170,000 y) absorb and reradiate the energy created in y) absorb and reradiate the energy created in the core, transporting it to the outer layers. the core, transporting it to the outer layers. Temperature is around 5,000,000 K.Temperature is around 5,000,000 K.

Convection zoneConvection zone – turbulent region where the – turbulent region where the solar material “boils” to quickly (1 week) move solar material “boils” to quickly (1 week) move heat to the outer layers. T ~ 2,000,000 Kheat to the outer layers. T ~ 2,000,000 K


Regions of the SunRegions of the Sun PhotospherePhotosphere – “surface” of the Sun that – “surface” of the Sun that

radiates visible light. Convection cells can radiates visible light. Convection cells can be seen as granules – T ~ 5800 K be seen as granules – T ~ 5800 K

SunspotsSunspots –highly variable, dark, cool –highly variable, dark, cool regions in the photosphere. T ~ 3500 Kregions in the photosphere. T ~ 3500 K

ChromosphereChromosphere - thin (2000 km) layer - thin (2000 km) layer outside photosphere in which Hydrogen outside photosphere in which Hydrogen absorbs radiation and reemits it as red absorbs radiation and reemits it as red light (H-alpha). Jagged outer edge has light (H-alpha). Jagged outer edge has dancing “flames” or spicules.dancing “flames” or spicules.


Regions of the SunRegions of the Sun Transition regionTransition region – very thin (100 km) layer in – very thin (100 km) layer in

which temperature rises from 20,000 to 10which temperature rises from 20,000 to 1066 K K CoronaCorona - very sparse outer ionized gas region - very sparse outer ionized gas region

with loops and streamers of magnetic field. with loops and streamers of magnetic field. Temperature ~ 10Temperature ~ 1066 K K

Solar Movie shows:

1) Photosphere

2) Chromosphere

3) Corona


Solar InteriorSolar Interior Sun has many Sun has many

oscillation modesoscillation modes Helioseismology is Helioseismology is

used to study the used to study the interior of the Sun interior of the Sun and to learn about and to learn about the convection the convection regionregion

3 SOHO 3 SOHO instrumentsinstruments

Computer simulation


Sunspot and Convection Sunspot and Convection CellsCells

Optical sunspot Optical sunspot image from the image from the Vacuum Tower Vacuum Tower telescope at the telescope at the Sacramento Peak Sacramento Peak National Solar National Solar Observatory with100 Observatory with100 km resolutionkm resolution

Shows granules from Shows granules from convection - each is convection - each is about 1000 km about 1000 km across and lasts for across and lasts for about 10 minutesabout 10 minutes


Solar ChromosphereSolar Chromosphere Maps of the solar Maps of the solar

chromosphere chromosphere are made by are made by observing light in observing light in the H-alpha linethe H-alpha line

Light is emitted Light is emitted in the H-alpha in the H-alpha line when an line when an electron jumps electron jumps down from the down from the n=3 shell to the n=3 shell to the n=2 shell in n=2 shell in HydrogenHydrogen


Solar Transition RegionSolar Transition Region

TRACE = Transition TRACE = Transition Region And Coronal Region And Coronal ExplorerExplorer

Blue = 360,000 KBlue = 360,000 K Green = 900,000 KGreen = 900,000 K Red = 2,700,000 KRed = 2,700,000 K White = sum of all 3White = sum of all 3

4/26/98


Solar CoronaSolar Corona Only easily visible during solar eclipseOnly easily visible during solar eclipse Eclipses can be created artificially in Eclipses can be created artificially in

coronographscoronographs

SOHO/LASCO movie


Sun in X-raysSun in X-rays

X-rays from X-rays from corona, corona, prominences, prominences, flares and flares and sunspotssunspots

Yohkoh movie


Sub- Atomic ParticlesSub- Atomic Particles

Atoms are made of Atoms are made of protons, neutrons and protons, neutrons and electronselectrons

99.999999999999% 99.999999999999% of the atom is empty of the atom is empty

spacespace Electrons have Electrons have

locations described by locations described by probability functionsprobability functions

Nuclei have protons and Nuclei have protons and neutronsneutrons

nucleus

mp = 1836 me


LeptonsLeptons An electron is the most common example of An electron is the most common example of

a lepton – particles which appear pointlikea lepton – particles which appear pointlike Neutrinos are also leptonsNeutrinos are also leptons There are 3 generations of leptons, each There are 3 generations of leptons, each

has a massive particle and an associated has a massive particle and an associated neutrinoneutrino

Each lepton also has an anti-lepton (for Each lepton also has an anti-lepton (for example the electron and positron)example the electron and positron)

Heavier leptons decay into lighter leptons Heavier leptons decay into lighter leptons plus neutrinos (but lepton number must be plus neutrinos (but lepton number must be conserved in these decays)conserved in these decays)


Types of LeptonsTypes of Leptons

LeptonLepton ChargeCharge Mass Mass (GeV/c(GeV/c22))

Electron Electron neutrinoneutrino

00 00

ElectronElectron -1-1 0.000510.0005111

Muon Muon neutrinoneutrino

00 00

MuonMuon -1-1 0.1060.106

Tau Tau neutrinoneutrino

00 00

TauTau -1-1 175175


Atomic ForcesAtomic Forces

Electrons are bound to Electrons are bound to nucleus by Coulomb nucleus by Coulomb (electromagnetic) force(electromagnetic) force

Protons in nucleus are Protons in nucleus are held together by residual held together by residual strong nuclear forcestrong nuclear force

Neutrons can beta-decay Neutrons can beta-decay into protons by weak into protons by weak nuclear force, emitting an nuclear force, emitting an electron and an anti-electron and an anti-neutrinoneutrino

F = k q1 q2

r2

n = p + e +


Neutrinos in the Standard ModelNeutrinos in the Standard Model The “standard model” of particle The “standard model” of particle

physics seeks to explain all the particles physics seeks to explain all the particles and forces that are observedand forces that are observed

In this model, there are 3 flavors of In this model, there are 3 flavors of neutrinos: electron, muon and tauneutrinos: electron, muon and tau

All three types of neutrinos are All three types of neutrinos are massless and travel at lightspeedmassless and travel at lightspeed

If neutrinos have mass, their mass could If neutrinos have mass, their mass could affect how the structure in the universe affect how the structure in the universe is formedis formed


Solar neutrino problem historySolar neutrino problem history First experiments (1969) that detected solar First experiments (1969) that detected solar

neutrinos found about half the rate expected neutrinos found about half the rate expected from models of nuclear reactions in the Sunfrom models of nuclear reactions in the Sun

The neutrinos predicted from the models The neutrinos predicted from the models (and detected in the experiments) are all (and detected in the experiments) are all electron neutrinos – so either:electron neutrinos – so either: the models were wrong the models were wrong something happened to the neutrinos on their way something happened to the neutrinos on their way

to the Earthto the Earth Many experiments in 1980s-1990s showed Many experiments in 1980s-1990s showed

the perhaps the neutrinos were changing the perhaps the neutrinos were changing flavors (from electron neutrinos to some flavors (from electron neutrinos to some other type)other type)


Solar neutrino problemSolar neutrino problem

4p 4p 44He + 2eHe + 2e++ + 2 + 2ee + 25 MeV + 25 MeV Chlorine atoms can capture Chlorine atoms can capture

neutrinosneutrinos


Homestake mine neutrino Homestake mine neutrino experimentexperiment

In an old mine in In an old mine in South Dakota (1967 – South Dakota (1967 – 1984)1984)

20 feet in diameter 20 feet in diameter 48 feet long, 48 feet long, held 100,000 gallons held 100,000 gallons

of tetrachloroethyleneof tetrachloroethylene located 4,900 feet located 4,900 feet

below ground surface.below ground surface.

Courtesy of Brookhaven National Laboratory


Homestake mine neutrino Homestake mine neutrino experimentexperiment

Ray Davis Jr. takes a dip in the 300,000 Ray Davis Jr. takes a dip in the 300,000 gallons of water that surrounds the gallons of water that surrounds the perchloroethylene tankperchloroethylene tank

Water lowers background ratesWater lowers background rates Detects electron neutrinos onlyDetects electron neutrinos only

Photo courtesy of Brookhaven National Laboratory


Sun in NeutrinosSun in Neutrinos

Super Super Kamiokande Kamiokande neutrino neutrino observatoryobservatory

500 day image500 day image 90 x 90 degrees 90 x 90 degrees

centered on Suncentered on Sun


SuperKamiokandeSuperKamiokande CAN DETECT ALL 3 CAN DETECT ALL 3

TYPES OF TYPES OF NEUTRINOSNEUTRINOS

Water Cerenkov DetectorWater Cerenkov Detector 41.4m (Height) x 39.3m 41.4m (Height) x 39.3m

(Diameter) (Diameter) 50,000 tons of pure water50,000 tons of pure water 1,000m underground1,000m underground 11,200 photomultiplier 11,200 photomultiplier

tubestubesSuperK detector


Where solar neutrinos come Where solar neutrinos come fromfrom


Neutrino OscillationsNeutrino Oscillations A pion decays in the upper atmosphere to a muon A pion decays in the upper atmosphere to a muon

and a muon neutrinoand a muon neutrino Neutrinos oscillate flavors between muon and tauNeutrinos oscillate flavors between muon and tau


Neutrino OscillationsNeutrino Oscillations

High energy High energy neutrinos that neutrinos that travel a short travel a short distance do not distance do not change their change their flavorflavor

Low energy Low energy neutrinos that neutrinos that travel a long travel a long distance have a distance have a 50% chance of 50% chance of changing flavorschanging flavors (m2c4) = 0.005 eV2


Neutrino Oscillations/KEKNeutrino Oscillations/KEK K2K (KEK to SuperK) is the new experiment K2K (KEK to SuperK) is the new experiment

testing neutrino oscillation resultstesting neutrino oscillation results Neutrinos produced at KEK are measured at Neutrinos produced at KEK are measured at

near detector and then shot 250 km across near detector and then shot 250 km across Japan to SuperK detectorsJapan to SuperK detectors

First events were detected in 1999 – confirm First events were detected in 1999 – confirm oscillations (56 seen, 80 expected by 2001)oscillations (56 seen, 80 expected by 2001)


SuperKamiokandeSuperKamiokande Severely damaged in accident on 11/12/01 Severely damaged in accident on 11/12/01

– over 5000 phototubes were destroyed– over 5000 phototubes were destroyed Is being rebuilt – online again by 2003Is being rebuilt – online again by 2003 First priority – resume K2K experiment by First priority – resume K2K experiment by

2003 half of previous phototubes2003 half of previous phototubes

Bottom of SuperK detector covered with broken PMTs after accident


Sudbury Neutrino ObservatorySudbury Neutrino Observatory >2000 meters below >2000 meters below

ground, in active mineground, in active mine Spherical detector, 12 m Spherical detector, 12 m

in diameter, filled with in diameter, filled with 1000 tons of heavy 1000 tons of heavy water, surrounded by 30 water, surrounded by 30 m cavity filled with m cavity filled with normal waternormal water

10,000 photomultipliers 10,000 photomultipliers measure light flashes measure light flashes when heavy water when heavy water catches neutrinos (e-)catches neutrinos (e-)


Comparing SuperK and SNOComparing SuperK and SNO SuperK detects all 3 types of neutrinos SuperK detects all 3 types of neutrinos

vs. SNO which detects e- neutrinos onlyvs. SNO which detects e- neutrinos only The numbers do not agree!The numbers do not agree! Use joint data set to predict total Use joint data set to predict total

numbers of neutrinos reaching Earthnumbers of neutrinos reaching Earth Prediction now agrees with solar Prediction now agrees with solar

modelsmodels Neutrino oscillations now confirmed!Neutrino oscillations now confirmed! Neutrinos have some mass!!Neutrinos have some mass!! Particle physics models must changeParticle physics models must change


Nobel Prize in Physics Nobel Prize in Physics 20022002 ““for pioneering contributions to for pioneering contributions to

astrophysics, in particular for the astrophysics, in particular for the detection of cosmic neutrinos”detection of cosmic neutrinos”

Raymond Davis Jr. & Masatoshi KoshibaRaymond Davis Jr. & Masatoshi Koshiba


Nobel Prize in Physics Nobel Prize in Physics 20022002 Raymond Davis Jr Raymond Davis Jr constructed a completely new constructed a completely new

detector, a gigantic tank filled with 600 tons of fluid, detector, a gigantic tank filled with 600 tons of fluid, which was placed in a mine. Over a period of 30 years which was placed in a mine. Over a period of 30 years he succeeded in capturing a total of 2,000 neutrinos he succeeded in capturing a total of 2,000 neutrinos from the Sun and was thus able to prove that fusion from the Sun and was thus able to prove that fusion provided the energy from the Sun. provided the energy from the Sun.

With another gigantic detector, called Kamiokande, a With another gigantic detector, called Kamiokande, a group of researchers led by group of researchers led by Masatoshi KoshibaMasatoshi Koshiba was was able to confirm Davis’s results. They were also able, on able to confirm Davis’s results. They were also able, on 23 February 1987, to detect neutrinos from a distant 23 February 1987, to detect neutrinos from a distant supernova explosion. They captured twelve of the total supernova explosion. They captured twelve of the total of 10of 101616 neutrinos (10,000,000,000,000,000) that passed neutrinos (10,000,000,000,000,000) that passed through the detector. through the detector.

The work of Davis and Koshiba has led to unexpected The work of Davis and Koshiba has led to unexpected discoveries and a new, intensive field of research, discoveries and a new, intensive field of research, neutrino-astronomy.neutrino-astronomy.


AMANDAAMANDA AAntarctic ntarctic MMuon uon AAnd nd

NNeutrino eutrino DDetector etector AArrayrray Purpose: high-energy (~ 1 Purpose: high-energy (~ 1

TeV or 10TeV or 101212 electron volt) electron volt) neutrinos from neutrinos from astrophysical point sources. astrophysical point sources.

302 PMTs on 10 strings at 302 PMTs on 10 strings at depths of 1500-2000 depths of 1500-2000 metersmeters

Videotape of lecture about Videotape of lecture about AMANDAAMANDA


Web ResourcesWeb Resources

Astro Capella Sun songAstro Capella Sun song http://www.pagecreations.com/astrocappella/sun.htmhttp://www.pagecreations.com/astrocappella/sun.htmll

Sun StructureSun Structure http://www.lmsal.com/YPOP/Spotlight/SunInfo/Structure.htmlhttp://www.lmsal.com/YPOP/Spotlight/SunInfo/Structure.html

Clear Skies Clear Skies http://www.swin.au/astronomyhttp://www.swin.au/astronomy The Particle Adventure http://particleadventure.org/

Nobel Prizes http://www.nobel.se

Ray Davis photosRay Davis photos http://www.bnl.gov/bnlweb/raydavis/pictures.htmhttp://www.bnl.gov/bnlweb/raydavis/pictures.htm


Web ResourcesWeb Resources

Sudbury Neutrino ObservatorySudbury Neutrino Observatory http://www.sno.phy.queensu.ca/http://www.sno.phy.queensu.ca/

John Bahcall’s neutrino pagesJohn Bahcall’s neutrino pages http://www.sns.ias.edu/~jnb/http://www.sns.ias.edu/~jnb/

Homestake Neutrino Laboratory Homestake Neutrino Laboratory http://www.blackhillsdata.com/nusl/solar_neuthttp://www.blackhillsdata.com/nusl/solar_neutrinos.htmrinos.htm

Super KamiokandeSuper Kamiokande

http://www-sk.icrr.u-tokyo.ac.jp/doc/sk/http://www-sk.icrr.u-tokyo.ac.jp/doc/sk/

Documents

Astronomy 305/Frontiers in Astronomy