syllabus
& course
expectations
safety,
tardy, classroom computer use, and honesty
Universe/publisher link: register as a student to use the resources
Astronomy
Picture of the Day
the
latest astrophysics discoveries
what's up in the sky
this week
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October 29 |
October 30 |
October 31 |
Nov 1 |
November 2 |
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(always done before class) |
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and perhaps a clue why radiation stops and convection starts in the outer layers 18(4): where are the solar neutrinos? pp. 407- 408: the search for the neutrinos, a personal viewpoint |
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| things you should know the answer to before coming to class | put
a pan of water on the stove: why does the pan not convect whereas the water does?? how can we calculate the time it takes a convection cell to travel from the bottom of the convective layer in the sun to the top surface of the sun? |
why does convection occur in the water above the pan, and not in the pan? why does convection occur in the outer parts of the sun and not the inner parts? what are the three different ways in which we are trying to detect solar neutrinos? why did it require the SNO machine to answer the question about the solar neutrinos? |
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| homework (written assignments to be turned in) |
please
bring at least 2 of the following calculations to class: (they should take 5 minutes each, maybe 10) verify the 1014 neutrinos per square meter (at earth) as claimed on page 386 how many Cl atoms are in the 100,000 gallon tank? (p. 386, 2nd column, last full paragraph) what's the reaction that converts Cl37 to Ar37? balance all 3 quantum numbers (p. 386, 2nd column, last full paragraph) |
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Super-Kamiokande and its photomultipliers surrounding the water (before it was destroyed in a chain reaction) Sudbury Neutrino Observatory detection physics the Mystery of the Missing Neutrinos -- this experiment won half of the 2002 Nobel Prize in PhysicsWeighing in on the Neutrino Mass -- the experiment that won the other half of the 2002 Nobel Prize in Physics |
close-up of magnetic coronal
loops the magnetic corona hear the sun quake see what helioseismology tells us see
the sun quake the
most amazing coronal mass ejection sunspot loops in the UV CMEs on the active sun |
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comet Holmes, brightest comet visible from US in 12 years |
| Monday, October 22 |
October 23 |
October 24 |
October 25 |
October 26 |
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will
check the mass-luminosity relation that you calculated from the graph in chapter 19 (assigned a while back) |
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(always done before class) |
see
last friday's stuff we still havent dont that |
Walker
15(2 on Pascal's principle.... how does pressure vary with depth?) Walker 15(3 on the origin and formula for the buoyant force & Archimed principele) Walker bottom of p. 549-551 on the derivation of the perfect gas law |
Universe
21(1,3) Walker bottom of p. 549-551 on the derivation of the perfect gas law |
16(6) on conduction, convection, and radiation 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 atmosphere (p 196-197) convection in Jupiter (p 290-291) convection in the sun (p 396-397, 401-402) |
finish
yesterday's reading assignments |
| things
you should know the answer to before coming to class |
see last friday's questions |
from Walker, what is the range of the strong force? what does it act on? what is its strength (relative to, say, the electric force?) from Universe how did the temperature get to be so high at the center of the sun so that fusion could start? why doesn't the sun collapse under its own gravity? why does the gas pessure increase with depth in the sun? why does the gas temperature increase with depth in the sun? how does the energy released in fusion get to the surface? by what processes? |
see questions from yesterday |
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... be able to describe how (on the atomic or the macroscopic scale) how each of the three energy exchange methods work |
see yesterday's questions |
homework (written assignments to be turned in) |
for your fusion reaction (sign up on the classroom door), 1) show that the three integer conservation laws hold 2) find the energy released in Mev 3) find the efficiency of your fusion reaction if your nucleus is not listed in the table in the back of Walker, see chart of nuclides type in your nucleus in box at upper left... for example, if you need carbon-12, type in C12 |
bring to class: 1) assuming that half of the gravitational energy released by the sun (since birth) has been used for KE: if this energy is spread evenly over all particles in the sun, what temperataure would they be? 2) assuming that half of the gravitational energy released by the sun (since birth) has been used for light, how long would the sun have lasted at its present luminosity using solely gravitational energy? in each case, state any assumptions you make start the problem from the beginning (ignore anything we did in class), except for theformula for the gravitational energy of a sphere of mass M and radius R: -GM2/R |
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of the week |
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October 15 |
October 16 |
October 17 |
October 18 |
October 19 |
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bring lab book to class; see homework below |
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short
classes today |
jit due by
6:30 am |
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(always done before class) |
the search for dark matter is a fairly old article, but the theory is still correct although the experiments have become much more sensitive (yet without detecting anything).... the first few pages should be easy to read... but the article becomes intense and not appropriate for small children as it discusses the experimental search techniques |
statistics of exoplanets see questions below jk's summary of extrasolar planets properties see questions below |
see web stuff below |
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Walker 32(1) Universe 18(2) |
| things you should know the answer to before coming to class | what are the 2 other ways that we
can deduce the presence of dark matter (besides the shapes of galactic rotation curves)? |
what
are the 5 ways extrasolar planets have been detected? how was your planet detected? (it may have been detected in more than 1 way!) in which of the 3 extrasolar planetary categories does your planet belong? how did the three categories come to have the properties they did? |
how
do we tell a main sequence star from a giant or a supergiant or a white
dwarf from the spectrum? leftover question from yesterday: what are the other two planetary categories AND a) how did these systems come to be? b) which category is your planet in? |
from Walker, what is the range of the strong force? what does it act on? what is its strength (relative to, say, the electric force?) from Universe how did the temperature get to be so high at the center of the sun so that fusion could start? why doesn't the sun collapse under its own gravity? why does the gas pessure increase with depth in the sun? why does the gas temperature increase with depth in the sun? how does the energy released in fusion get to the surface? by what processes? |
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| homework (written assignments to be turned in) |
bring to class: parts C and D of the RW Mon lab [make sure that you show me the two equations for (2RS and 2RL) before procedding with calculations] |
due
in class today: for your planet (and using ONLY the observable quantities: period, radial velocity plot, and spectral/luminosity class of the star) 1) attach a printed copy of your planet's star's radial velocity curve 2) find the lower limit to your planet's mass 3) % difference between your value and the accepted value (in one of the extrasolar planet catalogs) (the % should be less than 2% unless your orbit is noticeably elliptical, in which case the difference might be 10%) d) the planet's orbit size e) % diff , compared to catalog f) a range for the planet's surface temperature (using a reasonable range for albedo) g) the likely composition of your planet based on its formation temperature (with justification) |
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mass/energy inventory of the universe typical MACHO micro-lensing event gravitational lens picure gallerybullet cluster from APOD 8/24/06 bullet-cluster animation/video from Chandra 2006... original article dark matter ring discovered in early 2007 Hubble animation |
statistics of exoplanets jk's summary of extrasolar planets properties weather on an extrasolar planet |
(from Science 10/12/07) |
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| Monday, October 8 |
October 9 |
October 10 |
October 11 |
October 12 |
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start RW Mon
lab (parts A and B to be completed) in the lab book that the supernova spectra lab is NOT in |
you pick your
extrasolar planet today in class |
bring your lab
book (RW Mon) to class |
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(always done before class) |
4(6, 7), boxes 4-2, -3 & -4 19(11) |
19(11) | 25(1-3) can be read quickly (basic stuff about what's our galaxy and how we figured out that we live in a galaxy) |
section 25(4) and box 25-2 |
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| things
you should know the answer to before coming to class |
how to get Newton's version of
Kepler's 3rd law why are there so many versions of Kepler's 3rd law? (p. 72, 81, 431) be able to complete the following sentence: for an eclipsing binary, the deeper eclipse (of the two eclipses that happen during one period) is ALWAYS the eclipse of the ___________ star (helpful hint question: in which eclipse is more area covered? have you made your cutouts????) |
how
to do parts A and B of the lab (page 17, green book) without any help from anyone else make sure you know 1) what measurements you need to make from the data (canary cardstock handout from today) to complete parts A and B 2) the physics equations you are going to use to obtain the quantities as always, make sure that 1) no line starts with a number 2) you dont even think about numbers until the very last line, AFTER you've solve for the unknown algebraically 3) each number has correct units 4) pictures are at least one-half page 5) a power of ten is indeed written that way ("e-free") |
how to get Newton's version of Kepler's 3rd law why are there so many versions of Kepler's 3rd law? (p. 72, 81, 431) be able to complete the following sentence: for an eclipsing binary, the deeper eclipse (of the two eclipses that happen during one period) is ALWAYS the eclipse of the ___________ star (helpful hint question: in which eclipse is more area covered? have you made your cutouts????) |
calculate the power in the mass-luminosity relation (the powers in the mass-luminosity relationships ?) for main=sequence stars |
how to determine the mass of a galaxy why/how the shape of the rotation curve -- figure 25-16, page 566 -- tells us that the galaxy contains dark matter what shape would the rotation curve have to be in order for us not to need dark matter? |
homework (written assignments to be turned in) |
if you didnt finish parts A and B yesterday in class, you can still get the major portion of the credit if you finish before class and bring it to class see thursday's assignment notify me by tonight at 8 pm if you can't find a radial velocity curve for your planet's star |
bring to class (to hand in): 1) a printed copy of your planet's star's radial velocity curve [if your planet's star has multiple planets, i.e., b, c, d, ...] bring the graph for ONLY ONE planet) see the catalogs below 2) from the physics equations we used in lab tuesday (N's version of K's 3rd law, with special units; the center of mass condition, the formula for speed in a circular orbit), show that mB3/(mA+mB)2 = PvA3/(2p)3 hint: start with N's version of K3 and then eliminate aB using the seesaw condition; then eliminate aA in favor of vA for star A |
bring to class (to hand in): RE-DO the calculation for the mass of the galaxy in box 25-2, EXCEPT you do it for the mass inside distance d (in kiloparsecs) where d (in kpc) = 0.7 x (number that the first letter of your last name is in the order of the alphabet).... e.g., if my last name is Kolena, the first letter of my last nameis K; K is the 11th letter of the alphabet, so I would find the mass inside the distance d = .7 x 11 kiloparsecs = 7,700 pc... you will of course need the orbit speed that goes with that distance from the graph on page 566 ______________ replacement problems for people who got less than 2/3 on a problem on last week's homework: In each case, answer the same questions that were asked on last week's assignment. 1) light curve for a new cepheid 2) 19(41) 3) new binary star: 61 Cygni A, B (see Appendix 4 for data) ______________ coming attractions: (probably due tuesday of next week) for your planet 1) attach a printed copy of your planet's star's radial velocity curve 2) find the lower limit to your planet's mass 3) % difference between your value and the accepted value (in one of the extrasolar planet catalogs) (the % should be less than 2% unless your orbit is noticeably elliptical, in which case the difference might be 10%) d) the planet's orbit size e) % diff , compared to catalog f) a range for the planet's surface temperature (using a reasonable range for albedo) g) the likely composition of your planet based on its formation temperature (with justification!) |
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the spectroscopic binary applet the eclipsing binary applet |
are periodic
extinctions
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Princeton
catalog of extrasolar
planets France catalog of extrasolar planets (this catalog is more likely to have a link to the radial velocity curve for your planet; however, the planets' names listed are NOT the constellation name/number by which you picked the planet yesterday.... so you will have to go to the Princeton catalog above to find the other names of your planets) |
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RW
Mon lab begins (page 17 of the green book; data on canary cardstock) |
supernova
spectra lab due |
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of the week |
distant
dwarf galaxy studied through gravitational lensing |
| Monday, October 1 |
October 2 |
October 3 |
October 4 |
October 5 |
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none
for students |
bring either
your computer to class (for lab) or a flash drive on which to save your
work |
jit due by
noon |
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(always done before class) |
28(2,3); see question below |
26(4):
on what standard candles can be used for finding distances to galaxies 26(6): on the clustering or superclustering of galaxies |
4(4)
including box 4-2 [prereading: 4(1-3)] |
19(9-10) Walker: read about center of mass and come to class knowing the equation for how to find out its location! |
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things you should know the answer to before coming to class |
here's
how the class responded to the last JIT question from Friday: what are the implications of the Hubble law (v = H d) proportionality?: 1) galaxies that are farther away are moving away from us faster (sorry, that's not an implication of the law; that's what the law says... there's a difference!) 2) the universe's expansion is accelerating 3) the universe's expansion is decelerating 4) the universe's expansion is uniform 5) we are at the center of the universe 6) we are near the edge of the universe 7) the universe's galaxies are collected in clusters UNfortunately, none of the above is an implication of hubble's law, so please be ready for today's class, by rethinking the implications, reading the assignment in the box above, and trying again |
so, we finally understand that the hubble law is telling us that there was a common origin (a common place, a common time) for all matter in the universe: a Big Bang.... how can we calculate how long ago that was? (yesterday's reading should tell you how, although you shouldnt have needed it.... it's just dvat physics!) please come knowing how to do the calculation and what the answer is! but let's explore that calculation (of the age of the universe) further: what acceleration (of the universe's expansion) was assumed in that simple dvat calculation? and how should the expansion be behaving, acceleration-wise? think about the forces you know and which one(s) might be important! so, if we know take the acceleration/deceleration of the expansion into account to improve our calculation (of the age of the universe, the time ago when the common origin was), how would that change 1) the calcuation of the age of the universe 2) the shape of the Hubble diagram (would the slope be constant? what would it be?) once again, yesterday's reading should be most helpful when we look at galaxies close by, when are we seeing them? how about galaxies far away? so what would the Hubble diagram look like if the universe were decelerating? accelerating? and so why do the nearby galaxies have small redshifts? why do the distance galaxies have large redshifts? can we look far enough back in time to see this effect? consider the spherical-surface universe.... in which direction is it expanding? can we point to a place/direction where the Big Bang occurred? who/what was all together at the Big Bang? what has happened since? |
KNOW Kepler's laws (be able to state them without having to look them up in the book) what physics law(s) does each one hide? |
besides the JIT questions, be thinking about what 5 things both orbits in a binary system have in common where did the 4p2/G go in the equation on page 431? is its value = 1? how can that be? |
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homework (written assignments to be turned in) |
homework
on magnitudes: 1) a) using only the apparent magnitude (vs time) graph on page 480, determine how many times delta Cephei is at brightest than when it is faintest (on this and all future parts, make sure you show me what you did; do not just announce the answer) b) determine the period of delta cephei (the figure caption has an incorrect period) and use it to determine the average luminosity (it's a log scale! treat accordingly!) using the period-luminosity diagram on the adjacent page (delta Cephei is a type I cepheid); then use this luminosity (relative to the sun) to determine its average absolute magnitude c) finally, find the distance to delta Cephei 2) a) advanced question 19(40) AND also find the difference in the b) their apparent magnitudes c) their absolute lagnitudes 3) the 4th-brightest appearing (and nearby) star in the sky, alpha centauri, is actually a double star with components cleverly named A and B.... the stars are so close that they cannot be seen indiviudally by the eye... using the data in Appendix 4, find the apparent magnitude of the combined light of the alpha Centauri AB system |
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the spectroscopic binary applet the eclipsing binary applet |
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supernova
remnant spectrum lab visit the link within the lab and make a list of 3 possible SNR candidates that you AND your partner might study based on the criteria mentioned; you can email your list to me in advance of class to "reserve" as long as you and your partner have agreed on the list |
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of the week |
