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April 18 |
April 19 |
April 20 |
April 21 |
April 22 |
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(p. 445) actually, there might be two (since there is a distinct break in the data) we will discuss the nuclear force and the H-R diagram in our shortened class |
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(always done before class) |
25(1.2) |
25(1-2) how to find the mass of a galaxy, dark matter! 25(4) some other questions to think about as you are reading section 25(4): 1) how do we know (from the rotation curve of the galaxy) that we have reached the end of the galaxy? 2) why is the rotation curve of the galaxy linear (with positive slope) inside a radius of 2000 pc? what is that linearity telling us? |
plus check out (spend a good 30 - 40 minutes on) the links on the matter-energy inventory page you should be able to describe 1) macrolensing (what effects do we observe? what kind of objects are doing this?) 2) microlensing (same questions as above) 3) what kinds of stuff might this dark matter be? why are we unhappy with the present solutions to the dark matter problem? |
introduction to nuclear physics: Walker 32(1) |
although you can start on the stuff below postponed till monday: Walker 29(6) on relativistic energy and antimatter and 32(4) on nuclear binding energy coming attractions: Universe 18(1,2) and a JIT for Tuesday |
homework |
bring ON PAPER (to be handed in in class) a calculation of the mass of the galaxy inside the distance assigned to you in class today make sure that you can find a radial velocity curve for "your planet's" star soon (so that i can help you find it if it's not readily available) see friday's links under "web stuff" |
bring to class and solution to the black hole inequality that we ended class with tuesday: what values for Mi will solve the inequality correctly? you can use guess and check (bring some guess-and-check values to class) or if you think you know how to use your calculator to solve it (perhaps graphically, perhaps otherwise), that's fine too |
due
by 5 pm, for your planet (whose name you should prominently record at top of assignment: 1) find/print a copy of the radial velocity curve... see links below (& make sure you attach a copy to what you turn in) 2) determine vvsin i in au/yr (it may not agree with the "printed" value) 3) period (in yr) 4) calculate 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 7) find orbit size of your planet (au) 8) comparison of orbit size, min. mass with published values |
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inventory of universe's mass-energy White's dark matter page neutralinos & axions: how to search for dark matter Abell 2218: A Galaxy Cluster macro-lens |
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(and still somewhat controversial) |
france exoplanets catalog princeton exoplanets catalog (includes spectral/luminosity class and RA/dec coordinates) |
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(including comparisons to "standard stars") |
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cosmic shell
seekers find a beauty |
are periodic
extinctions
The
Great Dying: the |
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April 11 |
April 12 |
April 13 |
April 14 |
April 15 |
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jit due at 1
pm |
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(always done before class) |
[start 4(5-7), most of which should be a review] |
19(9-10) |
instead, a) have you found the book's three different versions of Kepler's 3rd law? b) can you figure out how to get Newton's version of Kepler's 3rd law from more basic physics? |
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homework |
bring
to class (in your lab book): 1) RW Mon completed through parts A and B 2) RW Mon's eclipses have flat bottoms... what situations would produce eclipses with pointy bottoms? 3) for an eclipse with flat bottoms, and points A, B, C, D being start of the eclipse, start of the flat bottom piece, end of the flat bottom piece, and end of the entire eclipse. draw 4 diagrams showing where the small star is relative to the big star 4) complete the sentence: the deeper eclipse is always the eclipse of the ___________ star (hint: first answer the question: in which eclipse is more star area covered?) (i believe the eclipsing binary and spectroscopic binary applets can be used to answer most/all the quesitons above... except, the eclipsing binary applet appears to have 2 mistakes... can you find them?) |
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a visible shock wave from a plane traveling faster than sound similarly, a bow shock near a young star Cygnus loop shock wave from a supernova: as the shock encounters interstellar gas, it heats it up, causing it to fluoresce |
the eclipsing binary applet RW Mon velocity curve and light curve |
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before 10:30 pm check |
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April 4 |
April 5 |
April 6 |
April 7 |
April 8 |
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bring a list of 3 examples of fluorescing astronomical objects to class TO
HAND IN (you can reference a picture in the book if you want or an object we encountered in a previous lab... ) also, make a stab as to whether the fluorescence is excited by uv light or by KE via a collision |
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(always done before class) |
questions to think about: 1) what does the balmer series of hydrogen lines get more play than the other series? 2) are there energy levels above 13.6 ev of energy? can the electron be "there"? 3) what does the Bohr model predict for the ionization energy of singly-ionized helium? for doubly-ionized lithium,? 4) you should now recognized that you understand why a neutral gas in transparent whereas a completely ionized gas is opaque... explain how the Bohr model shows this |
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also look at the helium and calcium energy level diagrams in your blue book and be ready to answer the same questions we answered about hydrogen in class today: 1) at what temperature(s) will stars show strong dark lines in the visible? 2) at what temperature(s) will stars show strong dark lines in the infrared? 3) ... in the ultraviolet? help on interpreting the calcium and helium energy level diagrams (which are a lot more complicated than hydrogen's): 1) energy (in ev) is still plotted up 2) the number corresponding to each transition connecting a pair of levels is the wavelength of light required in ANGSTROMS to effect that transition (to convert to nanometers, divide the angstrom number by 10; i.e., visible light wavelengths are 4000 - 7000 angstrons) |
doppler effect: 5(9) |
3(5) on solar eclipses just in case we can see the one this afternoon (see below) Walker 14(6) suggested, for help with doppler effect |
homework |
estimate
of solar corona temperature brought to class (on paper, to hand in;
show work) today use the FeXIV line in the flash spectrum for your temperature estimate |
doppler
applet doppler effect assignment due in class today |
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Orion's Great Nebula & the Trifid Nebula are starbirth sites; note that red fluorescing nebulas can only surround BLUE (uv-emitting stars) The Helix Nebula
& The Crab Nebula
& [these
two supernovas left behind neutron stars (stars made entirely of
neutrons that are about the size of durham)] fluorescence in the
solar
system: A Perseid Aurora
& Comet tails
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lab 5: image processing, part 2: stars sizes and magnitudes now due saturday at noon: solar luminosity & radius lab remember that you also have to determine the temperature of the sun (from your measurements of luminosity and radius); it's not written on the lab sheet! also, remember to always do % differences between your measured or calculated quantities and any "known" quantities! |
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 It Orbits a Star, but Does It Qualify for Planethood? |
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Era of Galaxy and Black Hole Growth Spurt Discovered |
sun
partially eclipsed in Durham |
