syllabus & course expectations & course links
Astronomy
Picture of the Day the
latest astrophysics discoveries
what's up in the sky
this week
Skywatcher's
Diary for this month
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October 31 |
November 1 |
November 2 |
November 3 |
November 4 |
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(always done before class) |
what are the different kind of nebula? which could lead to star formation in the future? which indicate that star formation has recently taken place? |
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the big question that I will ask you (after we take care of looking at the varioius calculations): how does a cloud/nebula not in the process of contracting (which includes the vast majority of clouds in the galaxy) turn into a cloud that is? if you write down the equation for the total energy of the cloud (KE + GE), the TWO answers should be apparent (as they also are if you have done the reading) |
and the green book pages 27-31 what changes occur in the appearance of a protostar as it progresses through its various phases? how do astronomers know how long a protostar spends in various phases? |
(and read the captions!) on thursday and friday web links below |
| homework |
bring
to class, on paper to hand in: a) name of your nebula type b) physical conditions: temperature = ? (Kelvin) mass = ? (solar masses) radius = ? (parsecs) reference page number from text where you got the above numbers c) calculate (1) the kinetic energy of the nebula (in Joules) (2) the gravitational energy of the nebula (ditto) (3) the total energy of the nebula (ditto) (4) conclusion about whether the nebula is expanding or contracting from calculations above Make sure that your calculation is done in SI units Check your units!! |
bring
to class (on paper that you will hand in): 1) yesterday's assignment 2) determination of the free-fall time of the sun by a) first completing the dimensional analysis problem that we started in class yesterday (and finding tff in terms of G,M,and R) b) substituting in the relevant numbers and finding the free fall time in years 3) calculating the gravitational lifetime of the sun (using the physics we did in class yesterday) in years |
final
project suggestions |
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the GMC at the heart Of Orion Dark Bok
Globules in IC 2944 star formation: star formation propagation(grav collapse induced by shock wave from O/B stellar winds) M16 before
hubble shock-wave
triggered starbirth star
death/supernova: Cygnus
loop shock wave spiral shock waves in galaxies: M51 as seen by
Hubble 2005 M83's emission nebulae
and its spiral arms a bow shock near LL Orionis galaxy collisions: the Antennae: visible and infrared and x-ray |
(theory in pictures) the first observations of jets and
disks during stellar
birth Stellar
Disks Set Stage for
disks without
jets: planet
building?:
Orion Nebula
Mosaic and Protoplanetary Disks |
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Glimmer of first stars spied?.... Spitzer Press Release .... others say "not so fast..." astronomers on verge of seeing black hole? |
Andromeda galaxy Mars & Uranus globular cluster M15 Pleiades h and c Persei double cluster open cluster M38 double star Albireo |
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October 24 |
October 25 |
October 26 |
October 27 |
October 28 |
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(always done before class) |
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16(6) on conduction, convection, and radiation 17(2) on the maxwell-boltzmann distribution and origin of the perfect gas law questions: 1) calculate the temperature required at the center of the sun (to produce the known pressure, from the green book... use the actually density at the center of the sun!!) 2) bring examples from your own common personal experience of you gaining (or losing) energy by radiation... by conduction.... bring 3 or 4 examples from your living environment (i.e., on earth) of energy transfer by convection... and you thought i forgot: what observational evidence do astronomers have that the more massive stars leave the main sequence before less massive stars? (what do astronomers observe that shows them this) |
convection is everywhere (and especially see the pictures & captions): convection in the kitchen and in a greenhouse (bottom of p 182 & top of p 183) convection in the earth's core (p 184) convection in the earth's mantle ( p 189) convection in the earth's atmospher (p 196-197) convection in Jupiter (p 290-291) convection in the sun (p 396-397, 401-402) |
18(4) & p. 418 (should he have won the Nobel prize?) |
the solar neutrino problem: 18(4) & p. 418 (should he have won the Nobel prize?) Weighing in on the Neutrino Mass -- the experiment that won a Nobel Prize |
| homework |
nuclear
physics homework: pick a nuclear reaction calculate the light/KE released in Mev calculate the efficiency of the reaction |
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Weighing in on the Neutrino Mass -- the experiment that won a Nobel Prize the Mystery of the Missing Neutrinos |
detection reaction physics the superkamiokande detector before it was damaged by a freak chain-reaction processdamage to the SK detectoron 11/12/01 |
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is it cryovolcanoes or just cracks in the surface? |
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October 17 |
October 18 |
October 19 |
October 20 |
October 21 |
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jit
due by 2 pm |
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(always done before class) |
pp 575-576, 608-609, especially assocaited photos & diagrams two articles on how to search for dark matter (in particular the neutralino & the axion): The Search for Dark Matter (an older article, but more complete) Universe Reveals its Dark Side (a shorter update) the first "dark galaxy" |
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what types of particles are affected (and cause) the strong force? what is the range of the strong force? what is the strength of the strong force (relative to the electric force)? what is the typical density of a nucleus? what does binding energy mean? what is the conversion between uc2 and Mev? |
what keeps the sun from collapsing under its own gravity? what determines the gas pressure at any point inside the sun? why does the gas pressure increase as you get nearer the center of the sun? why does the temperature have to increase as you get nearer the center of the sun? how does the energy (kinetic & light) released in the nuclear fusion at the center? |
| homework |
see
Thursday |
bring to class a calculation of 1) the thermal speed of the average hydrogen atom on the surface of the sun 2) the FWHM line broadening (in nm) of the 3->2 transition of hydrogen in the sun |
for
Your Planet, (whose name you should prominently record at top of assignment: 1) find/print a copy of the radial velocity curve... see extrasolar planetary catalog links below (& make sure you attach a copy to what you turn in) 2) measure vvsin i from your graph and convert to au/yr (it may not agree with the "printed" value) 3) period (in yr) 4) calculate the system's mass function (in solar masses) 5) find mass of visible star (solar masses) from spectral/luminosity class given in one of the above links; reference 6) find minimum mass of your planet; document process & calculations [guess&check or calculator graphing] 7) find orbit size of your planet (au) 8) comparison of orbit size, min. mass with published values (see catalogs under web stuff) 9) find the luminosity of your star (you should be able to do this from your planet's star's spectral/luminosity type) 10) decide on a maximum and minimum albedo for your planet (based on your knowledge of albedoes present in the solar system) 11) find the minimum and maximum temperature of your planet 12) decide what's solid (and what isn't) at your planet's temperatures 13) print a finding chart for your planet's star... use The Sky software in back physics lab... use the find command to locate your star... if you need help, come get me |
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inventory of universe's mass-energy White's dark matter page typical MACHO micro-lensing event gravitational lens picure gallery first
image of an extrasolar
planet |
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france exoplanets catalog princeton exoplanets catalog (includes spectral/luminosity class and RA/dec coordinates |
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central black hole cradles stars Andromeda shines in the infrared Deep Impact finds more dust than ice in comet |
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October 10 |
October 11 |
October 12 |
October 13 |
October 14 |
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(always done before class) |
in October Sky and Telescope question to think about for class: how should a galaxy's rotation curve look if we were truly at the end of the galaxy? |
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| homework |
show
(starting from Kepler's 3rd law, the center of mass condition, and the
definition of orbital speed) that (Mi sin i)3/(Mi + Mv)2 = P (Vv sin i)3/(8p3) i used the Kepler's 3rd law version that has the special units (so that 4p2/G = 1) |
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October 3 |
October 4 |
October 5 |
October 6 |
October 7 |
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jit due by 2
pm see homework below |
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(always done before class) |
& binary star sections 19(9,10): questions you surely know the answer to from the reading: 1) what are the 3 different ways that a binary can be detected on Earth OTHER than actually seeing two stars in the telescope orbit over time? (in other words, if we only see one point of light in the telescope, how could we infer that the system was a pair of stars?) 2) Suppose we observe a spectroscopic binary over a complete period like the one Toan and James showed you in the green book.... do you have a plan for figuring out the masses of the two stars? in other words, given what's observed, how do you use the physics equations to find the masses of the individual stars? |
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find out what's going on inside your galaxy and bring questions about the reading |
| homework |
find
the power in the power law for the mass-luminosity relation ditto for the mass-radius relation that's in the green book |
bring
to class (done in your lab book) 1) the orbital speed of each star 2) the orbit radius of each star, in the units requested (and you dont have to stop there, you can continue ...) |
for your "distance" find the mass of the galaxy inside your distance if you didnt do the power calculations (see wednesday), make sure that you do them and bring them to class today for monday, finish through part E of the lab |
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are periodic
extinctions
The
Great Dying: the |
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(samples to be returned soon) "Big Baby" galaxies found in young universe Tycho's SNR provides evidence for cosmic rays |
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astro pages for september2005
astro pages for august 2005