Astronomy 101 The Solar System Tuesday, Thursday 2:30-3:45 pm
Hasbrouck 20 Tom Burbine [email protected] Slide 2 Course
Course Website:
http://blogs.umass.edu/astron101-tburbine/http://blogs.umass.edu/astron101-tburbine/
Textbook: Pathways to Astronomy (2nd Edition) by Stephen Schneider
and Thomas Arny. You also will need a calculator. Slide 3 Office
Hours Mine Tuesday, Thursday - 1:15-2:15pm Lederle Graduate
Research Tower C 632 Neil Tuesday, Thursday - 11 am-noon Lederle
Graduate Research Tower B 619-O Slide 4 Homework We will use Spark
https://spark.oit.umass.edu/webct/logonDisplay.d
owebcthttps://spark.oit.umass.edu/webct/logonDisplay.d owebct
Homework will be due approximately twice a week Slide 5 Astronomy
Information Astronomy Help Desk Mon-Thurs 7-9pm Hasbrouck 205 The
Observatory should be open on clear Thursdays Students should check
the observatory website at: http://www.astro.umass.edu/~orchardhill
for updated information http://www.astro.umass.edu/~orchardhill
There's a map to the observatory on the website. Slide 6 Final
Monday - 12/14 4:00 pm Hasbrouck 20 Slide 7 HW #10 Due today Slide
8 HW #11 Next Tuesday Slide 9 If you want to find life outside our
solar system You need to find planets http://exoplanet.eu Slide 10
Extrasolar Planets Today, there are over 400 known extrasolar
planets Slide 11 Star Names A few hundred have names from ancient
times Betelgeuse, Algol, etc. Another system: A star gets name
depending on what constellation it is in With a Greek letter at the
beginning Alpha Andromeda, Beta Andromeda, etc. Only works for 24
brightest star Slide 12 Star Names now Stars are usually named
after the catalog they were first listed in HD209458 is listed in
the Henry Draper (HD) Catalog and is number 209458 HD209458a is the
star HD209458b is the first objects discovered orbiting the star
Slide 13 Our Solar System has basically two types of planets Small
terrestrial planets Made of Oxygen, Silicon, etc. Large gaseous
giants Made primarily of hydrogen and a little helium Jupiter - 90%
Hydrogen, 10% Helium Saturn 96% Hydrogen, 3% Helium Uranus 83%
Hydrogen, 15% Helium Neptune 80% Hydrogen, 20% Helium Slide 14
Things to Remember The Milky Way has at least 200 billion other
stars and maybe as many as 400 billion stars Jupiters mass is 318
times than the mass of the Earth Slide 15 Question: How many of
these stars have planets? Slide 16 What is the problem when looking
for planets? Slide 17 The stars they orbit are much, much brighter
than the planets Slide 18 Infrared image of the star GQ Lupi (A)
orbited by a planet (b) at a distance of approximately 20 times the
distance between Jupiter and our Sun. GQ Lupi is 400 light years
from our Solar System and the star itself has approximately 70% of
our Sun's mass. Planet is estimated to be between 1 and 42 times
the mass of Jupiter. http://en.wikipedia.org/wiki/Image:GQ_Lupi.jpg
Slide 19 Slide 20 So what characteristics of the planets may allow
you to see the planet Slide 21 Planets have mass Planets have a
diameter Planets orbit the star Slide 22
http://upload.wikimedia.org/wikipedia/commons/d/de/Extrasolar_Planets_2004-08-31.png
Slide 23 Jupiter H, He 5.2 AU from Sun Cloud top temperatures of
~130 K Density of 1.33 g/cm 3 Hot Jupiters H, He As close as 0.03
AU to a star Cloud top temperatures of ~1,300 K Radius up to 1.3
Jupiter radii Mass from 0.2 to 2 Jupiter masses Average density as
low as 0.3 g/cm 3 Slide 24 1001,00010 (lightyears) Slide 25 Slide
26 Some Possible Ways to detect Planets Pulsar Timing Radial
Velocity (Doppler Method) Transit Method Direct Observation Slide
27 Pulsars Rotating Neutron Stars Have densities of 810 13 to 210
15 g/cm Slide 28
http://www-learning.berkeley.edu/astrobiology/powerpointhtml/sld035.htm
Slide 29 http://en.wikipedia.org/wiki/Image:Ssc2006-10c.jpg Slide
30 Would you want to live on a pulsar planet? Slide 31 Center of
Mass Distance from center of first body = distance between the
bodies*[m2/(m1+m2)]
http://en.wikipedia.org/wiki/Doppler_spectroscopy Slide 32 Radial
Velocity (Doppler Method)
http://www.psi.edu/~esquerdo/asp/shifts.jpg Slide 33
http://astronautica.com/detect.htm Slide 34
http://www.psi.edu/~esquerdo/asp/method.html Wavelength Slide 35
www.physics.brandeis.edu/powerpoint/Charbonneau.ppt Slide 36 Bias
Why will the Doppler method will preferentially discover large
planets close to the Star? Slide 37 Bias Why will the Doppler
method will preferentially discover large planets close to the
Star? The gravitational force will be higher Larger Doppler Shift
Slide 38 Transit Method When one celestial body appears to move
across the face of another celestial body Slide 39 When the planet
crosses the star's disk, the visual brightness of the star drops a
small amount The amount the star dims depends on its size and the
size of the planet. For example, in the case of HD 209458, the star
dims 1.7%.
http://en.wikipedia.org/wiki/Extrasolar_planets#Transit_method
Slide 40 One major problem Orbit has to be edge on Slide 41 Eclipse
Planet passes in back of a star
http://www.news.cornell.edu/stories/March05/Planet-eclipse-Plot.mov
Because the star is so much brighter than a planet, the dip in
brightness is smaller during an eclipse than a transit Usually to
maximize the effects of an eclipse, astronomers observe these
eclipses at infrared wavelengths Slide 42 Slide 43 Direct
Observation Infrared Image Slide 44
http://www.news.cornell.edu/stories/March05/extrasolar.ws.html
http://nai.nasa.gov/library/images/news_articles/319_1.jpg
VisibleInfrared Slide 45 Slide 46
http://en.wikipedia.org/wiki/Image:Extrasolar_planet_NASA2.jpg
Slide 47 How did these Hot Jupiters get orbits so close to their
stars? Slide 48 Formed there but most scientists feel that Jovian
planets formed far from farther out Migrated there - planet
interacts with a disk of gas or planetesimals, gravitational forces
cause the planet to spiral inward Flung there gravitational
interactions between large planets Slide 49 Kepler Mission Kepler
Mission is a NASA space telescope designed to discover Earth-like
planets orbiting other stars. Using a space photometer, it will
observe the brightness of over 100,000 stars over 3.5 years to
detect periodic transits of a star by its planets (the transit
method of detecting planets) as it orbits our Sun. Launched March
6, 2009 Slide 50 Kepler Mission
http://en.wikipedia.org/wiki/File:Keplerpacecraft.019e.jpg Slide 51
Kepler Mission The Kepler Mission has a much higher probability of
detecting Earth-like planets than the Hubble Space Telescope, since
it has a much larger field of view (approximately 10 degrees
square), and will be dedicated for detecting planetary transits.
There will a slight reduction in the star's apparent magnitude, on
the order of 0.01% for an Earth- sized planet. Slide 52
www.physics.brandeis.edu/powerpoint/Charbonneau.ppt Slide 53 Slide
54 KEY D 22255311322343524233524343125151 35254313 Slide 55 What
Planet do we know the most about? Slide 56 Earth Slide 57
http://college.cengage.com/geology/resources/protected/physicallab/thelab/interior/index.htm
Slide 58 Earths Interior Slide 59 Slide 60 Earths crust 46.6% O
27.7% Si 8.1% Al 5.0% Fe 3.6% Ca 2.8% Na 2.6% K 2.1% Mg Slide 61
Earth is made of minerals Slide 62 Mineral A naturally occurring,
homogeneous inorganic solid substance having a definite chemical
composition and characteristic crystal structure Slide 63 Olivine
(Mg, Fe) 2 SiO 4 Fayalite (Fa) - Fe 2 SiO 4 Forsterite (Fo) - Mg 2
SiO 4 Slide 64 Pyroxenes XY(Si, Al) 2 O 6 X can be Ca, Na, Fe +2,
Mg, Zn, Mn, and Li Y can be Cr, Al, Fe +3, Mg, Mn, Sc, Ti, V, and
Fe +2 Augite Ferrosilite Slide 65 How do we know whats in the
interior of the Earth? Slide 66 Seismic Waves vibrations created by
earthquakes Slide 67 Seismic Waves P waves primary waves (pushing)
travel faster can travel through anything S waves secondary (side
to side) travel slower only through solids Slide 68
http://alomax.free.fr/alss/examples/hodo/hodo_ex
ample.htmlhttp://alomax.free.fr/alss/examples/hodo/hodo_ex
ample.html Slide 69 Surface Waves Travel on the surface of the
Earth Love Wave side by side
http://www.geo.mtu.edu/UPSeis/images/Love_ani
mation.gifhttp://www.geo.mtu.edu/UPSeis/images/Love_ani mation.gif
Rayleigh Wave rolling movement
http://www.geo.mtu.edu/UPSeis/images/Rayleigh
_animation.gifhttp://www.geo.mtu.edu/UPSeis/images/Rayleigh
_animation.gif Most of the shaking felt from an earthquake is due
to the Rayleigh waves Slide 70 Slide 71 P (primary) waves S
(secondary) waves Surface waves: Rayleigh and Love waves Slide 72
Slide 73 Slide 74 Slide 75 Slide 76 Slide 77 Richter Scale Measures
the magnitude of an earthquake Single number to quantify the amount
of seismic energy released by an earthquake. Amplitude of largest
displacement Under 6.0 - At most slight damage to well-designed
buildings. Can cause major damage to poorly constructed buildings.
6.1-6.9 - Can be destructive in areas up to about 100 kilometers
across where people live. 7.0-7.9 - Major earthquake. Can cause
serious damage over larger areas. 8 or greater - Great earthquake.
Can cause serious damage in areas several hundred kilometers
across. Slide 78 Slide 79 Slide 80 Slide 81 How do we get
information? The precise speed and direction of the waves depends
on the composition, density, pressure, temperature, and phase
(solid or liquid) Slide 82 Which of these bodies have they used
seismic waves to study? Slide 83 Earth Moon Apollo missions brought
seismometers to Moon to study moonquakes Slide 84 How can you study
the interior of a planet from space? Slide 85 Density Density =
mass/volume If the density is higher than the surface rock, there
must be denser material in the interior Slide 86 Gravity If you can
measure gravity (force) with a spacecraft as it rotates around a
body, you can determine how mass is distributed on the body Slide
87 Magnetic Field Tells if a planet has a molten metal interior
Slide 88 http://www.gcsescience.com/pme1.htm Slide 89 Earths
magnetic field is believed to be caused by the convection of molten
iron, within the outer liquid core along with the rotation of the
planet http://geomag.usgs.gov/images/faq/Q6.jpg Electrons flow
Slide 90
http://www.scifun.ed.ac.uk/card/images/left/earth-magfield.jpg
Slide 91 Magnetic pole moves
http://science.nasa.gov/headlines/y2003/29dec_magneticfield.htm
Slide 92 Slide 93 North Magnetic Pole However, the "north pole" of
a magnet is defined as the one attracted to the Earth's North
Magnetic Pole By this definition, the Earth's North Magnetic Pole
is physically a magnetic south pole Slide 94 Glatzmeier and Roberts
simulations : Slide 95 Geomagnetic Reversals Based upon the study
of lava flows of basalt throughout the world, it has been proposed
that the Earth's magnetic field reverses at intervals, ranging from
tens of thousands to many millions of years The average interval is
~250,000 years. The last such event, called the Brunhes- Matuyama
reversal is theorized to have occurred some 780,000 years ago.
Slide 96 The present strong deterioration corresponds to a 10 15%
decline over the last 150 years and has accelerated in the past
several years Geomagnetic intensity has declined almost
continuously from a maximum 35% above the modern value, which was
achieved approximately 2000 years ago. At this rate, the dipole
field will temporarily collapse by 30004000 AD Slide 97 What may
happen during the reversal? There may be a slight rise in the per
capita cancer rate due to a weaker magnetic field. We may also be
able to see the northern lights at lower latitudes If you own a
compass, it will have difficulty finding north until the
magnetosphere settles. Slide 98 Van Allen Belts The Van Allen
radiation belts are rings of energetic charged particles around
Earth, held in place by Earth's magnetic field Outer belt primarily
electrons Inner belt primarily protons Slide 99
http://www.nytimes.com/2006/08/10/science/space/10vanallen.html
Slide 100 Van Allen Belts
http://en.wikipedia.org/wiki/Image:Van_Allen_radiation_belt.svg
Slide 101
http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html Slide
102 James Van Allen Sent a Geiger Counter on the first US satellite
Explorer 1 The Geiger counter began clicking madly as soon as it
reached orbit Slide 103 Auroras Auroras natural light displays
Collision of charged particles from Earth's magnetosphere with
atoms and molecules of Earth's upper atmosphere The collisions in
the atmosphere electronically excite atoms and molecules in the
upper atmosphere. The excitation energy can be lost by light
emission or collisions. http://www.youtube.com/watch?v=pLi4T4JCALk
Slide 104 Any Questions?
