Astrophysics fall trimester  2006

 syllabus   &  course expectations

 Astronomy Picture of the Day        the latest astrophysics discoveries
  what's up in the 
sky this week       Skywatcher's Diary for this month

September 25
September 26
September 27
September 28
September 29
 extended weekend

no class

only faculty have school
(always done before class)
5(10) on the Doppler effect that hopefully you read for last friday 
26(1-3) on galaxies

26(4) on distances to galaxies

26(5) on the expanding universe
4(1-3) on the history of astronomy up to the 1500s


4(4 - 7) on Kepler's laws and gravity:
key sections are 4(4 and 7)

 box 4-4 is important also
things you should know the answer to before coming to class

is the doppler shift in wavelength a significant fraction of the wavelength of starlight?

what is the doppler shift formula in terms of frequency (the book only writes the one for wavelength)
why do we think the universe is expanding?

what are the implications of hubble's law?
(what IS Hubble's law?)
(why is it that the farthest galaxies are farthest away?)

how do astronomers get distances to galaxies?

why can't galaxies' redshifts be doppler shifts?
(i.e., due to the motion of the galaxies relative to us)?

so what is the redshift is due to? 

KNOW Kepler's 3 laws
and their implications

(be able to state them from memory and be able to describe in english what they mean)

what physics laws are Kepler's 3 laws
hiding in disguise?

know how to get Kepler's 3rd law from Newtonian laws

(written assignments
to be turned in)

bring to class:

determine the value of 1/H  (in years)

(2 units changes and an inverse)

1) find the distance to delta Cephei (given the data on page 480 and using the period-luminosity graphs on page 481... delta cephei is a type I cepheid
(we outlined the method in class; 2 digit accuracy is sufficient

2) find out how much taller you would grow during your future lifetime IF your body participated in the expansion of the universe; to do this
a) first calculate the speed of the top of your head as "seen" by your feet; use the value of H given in the text

b) assuming that this speed remains constant during your future, how much taller will you grow during the rest of your life?
web stuff
 doppler effect applet

a bow shock in the Orion nebula
 the Supernova Cosmology project is trying to measure how the expansion of the universe is changing (and therefore what the future history of the universe might be)

mass/energy inventory of the universe
 A Dark Force in the Universe 
  parents' jit
sun lab is due 
news & discoveries
 Hubble finds hundres of young galaxies in the early universe
if clear

weather by the hour

September 18
September 19
September 20
September 21
September 22
luminosity, radius, and temperature of the sun

(assuming it's clear)
bring PINK Bohr-atom handout to class
jit due by 8 am today
look at the calcium energy level diagram and answer the following:

1) what temperature ionizes neutral calcium?

2) in what temperature range is calcium singly ionized

3) at what temperature will visible-light neutral calcium lines be strong?

4) what temperature will allow for strong visible light emission in a fluorescing nebula?
bring spectra/sun properties lab book to class (so I can grade it this weekend)
(always done before class)

FK 5(8)
FK 19(5) but ONLY after you have answered JIT questions 2a

also box 7-2 which can be read anytime!
what is the story behind the H-R diagram?

what is being plotted?
why are stars in different places on the diagram?

know the doppler effect
things you should know the answer to before coming to class

see the JIT

can human experience the doppler effect in sound?
(can we hear a change in pitch due to moving objects?)


can humans experience the doppler effect in light?
(can we see a change in color due to moving objects?)

(written assignments
to be turned in)

to be brought to class today:

a) calculation of the luminosity of the sun
(using lab guide expectations: no numbers till end, units, etc)

b) a prediction of the color of the bulb-side wax
(starting with a temperature of the bulb, a calculation, and corrections for human interpretation)

c) ditto for color of  sun-side wax

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
web stuff

fluorescing hydrogen regions around hot stars help us trace the spiral arms and places of recent stellar birth

fluorescence in the solar system: 
the eclipsed sun shows a red fluorescing atmosphere (which reveals the flash spectrum)

flash spectrum with lines identified

A Perseid Aurora
 Aurora in Red and Yellow
show that the atmosphere can fluoresce (what's causing it?)

the fireballs in Jupiter's atmosphere created by comet Shoemaker-Levy

Comet tails
both fluoresce and reflect...
can you tell which is which?

 M57: the Ring Nebula
are planetary nebulas with hot uv-emitting white dwarfs at the center (white dwarfs are earth-sized), the death phase of stars like the sun and those less massive

spectrum of a planetary nebula

  starbirth nebula: Orion's Great Nebula & the Trifid Nebula are starbirth sites; note that red- fluorescing nebulas can only surround BLUE (uv-emitting stars)

The Crab Nebula
 Cas A are supernova remnants; this is the death phase of middle-mass stars... the fluorescence here is caused by the kinetic energy of blast wave that accompanied the supernova

[these two supernovas left behind neutron stars (stars made entirely of neutrons that are about the size of durham)]

gas in the Coma Cluster of galaxies

doppler effect applet

a bow shock in the Orion nebula


try to finish this week's lab while it's fresh in your mind
of the week
Xena becomes Eris
oldest recorded supernova

September 11
September 12
September 13
September 14
September 15
we will do the luminosity of the sun lab as soon as the sun makes its appearance
(be ready for appropriate dress)
weather is here
(always done before class)
7(6,7) & 8(3)
[it's assumed that you have already read 7(1,4) and 8(1-2,4-5)]
5(8): introduction to line spectra
Walker 31(1,2) 
Walker 31(3):
go through line-by-line making sure you understand where are the equations and ideas come from...

there will be
a) old physics laws put together in a new way

b) new physics that you have never studied before (and we will have to stop and take the time to learn)

c) wrong or omitted physics that you should notice

annotate your pink sheet with examples of (b) and (c) above
see yesterday's expectations;
I think some of us can do a bit better job

BROWSE the following in Walker to get a taste of angular physics:

10(1,2 up to mid p. 287)

moment of inertia at the bottom of p. 296

torque (or how wrenches work) on p.316

center of mass and balance on p. 330

conservation of angular momentum and ice skaters in example 11-9 on p. 339

see below

things you should know the answer to before coming to class

what 4 additional sources of energy have contributed to raising a planet's surface or interior  temperature beyond that calculated from the one we obtained by assuming only absorption of sunlight?)

what are 3 ways that astronomers or geolgists can tell that the interior of a planet is hot

(see Tuesday reading!)

review yesterday's question (4 sources of energy for heating planetary or surface temperatures)

be able to fill in all the missing algebra steps that were omitted on the pink sheet

as you browse Walker,
create a two-column table, where you write down ALL the first-semester-physics quantities that you learned last year
(about 12?),
e.g., displacement, velocity, acceleration, mass, etc  in the left column....
and then find and name the corresponding quantity in angular physics
(written assignments
to be turned in)
bring to class
(on a piece of paper that can be handed in):
calculated temperature of your planet (using last Friday's derived formula)
the real temperature of your planet
(look it up in your planet's chapter)

ratio of electric force between the proton and electron in a hydrogen atom to the gravitational force ;

bring on a piece of paper to hand in
web stuff
 information on Xena

 spectra lab due
 asteroid lab

make sure you follow the communication guidelines!

be prepared for luminosity of the sun lab on the first clear day of the week
news & discoveries
Pluto's Exotic Playmates
(and how/why the planets have migrated a bit since formation)
today's NY Times
(requires NYT registration)

September 4
September 5
September 6
September 7
September 8
no class
Labor Day

you may want to bring your computer today to do the asteroid image processing lab

see below for software

jit due by 8 am
(always done before class)



[remember that you have already read 19(2)]
7(1,4) and 8(1,2,4,5)

things you should know the answer to before coming to class

how astronomers use parallax to measure distance

where the formula
d = 1/p
came from
class presentation:
know the derivation of the formula
d = 1/p

what planet (in the solar system) would astronomers like to be living on to measure parallaxes?

important differences between terrestrial and jovian planets

basic features of the condensation-accretion theory of planetary formation

why terrestrials and jovians ended up so different in size/mass and composition

(written assignments
to be turned in)

now due sunday noon

for your star:
a) identify your star's name & the spectral/luminosity class listed in the Appendix

b) determine your star's temperature (in K)

c) determine the wavelength of max intensity for your star AND what color your star would appear to humans

d) use your star's apparent magnitude (along with the sun's apparent magnitude and sun's known flux) to determine your star's flux

e) determine your star's luminosity relative to the sun.... show work!

(your luminosity ratio should also match that given in Figure 19-14a)

f) the radius of your star (relative to sun)
[see box 19-4 and follow the procedure exactly]

(your answer should also match that given in Figure 19-14b)

g) if we define the sun as fist-sized, what real life object (either bring one or have a classroom object identified) that approximately matches your star's size

h) determine what fraction of your star's luminosity is emitted in the uv, in the visible, and in the ir
(using the spectrum explorer  applet)
web stuff

spectrum explorer
(launch the explorer; it requires java, so that must be enabled; 2 new windows should open in a minute or 2-- a useless one and one containing axes; on the latter, click on the "blackbody" button to add a blackbody, type in the temperature below the thermometer, and you'll find the %s in another new, tiny window that opens


software for today's  asteroid parallax lab:

we will use the HOU software

go to the following path on the T drive:

you should be able to double click on the setup.exe icon to install

(alternatively, you can just run it from the T drive)

images for asteroid parallax lab:

spectra lab now due Monday
of the week

SMART-1 hits moon

planet or failed star?

August 28
August 29
August 30
August 31
September 1

prepare lab book for spectra lab
(see below)
JITdue by 6 am today

although only 80% of JITs are required, everyone should plan to do the first one, if only to try out the process; if you do extra JITs, you will get extra credit

(always done before class)
Walker 28(1,2,6)

look at how the real formula is different than the on we came up with in class

look at some of the examples, qualitative and quantitative
5(6): know what kind of source
(solid, liquid, transparent gas, opaque gas, etc.)
produced what kind of spectrum:

there will be a short quiz at the beginning of this lab on the reading
[yes, we skipped 19(1)]:
how to distinguish between flux and luminosity

things you should know the answer to before coming to class
6 or more "behaviors" of light that are post-1800

of course you not only want to know the names but also what the behavior means and be able to give an example

know how to draw blackbody curves.... how does a hotter blackbody curve differ from a cooler one's curve.... and what is a blackbody?
still doing post-1800 behaviors of light

be ready! to describe

(written assignments
to be turned in)

tally of star properties
from both classes combined

web stuff


bring 2nd lab book to class image processing lab due

spectra lab begins

of the week

August 22
August 23
August 24
August 25
astronomical light detectors
image processing
more about light detectors 
(always done before class)

all of the lab guide

Sky on a Chip:
the Fabulous CCD
(TURQUOISE handout)

5(1): what is light?
5(1-2): what is light?
you should know some properties of light (e.g. wavelength or frequency)

and some behaviors of light (e.g., reflection, refraction)
see the Walker references on the syllabus
(but it doesn't have to be Walker)

perhaps you will learn some laws that go with the behaviors as you read?

maybe two sides of a page of notes while you're reading?
questions you should know the answer to before coming to class

what are the three pieces of info astronomers can record about an incoming photon?
(block D only got "color" or "wavelength" or "energy"  there are two more obvious, simpler answers)

(written assignments
to be turned in)

number the odd pages of your lab book

list of 10 properties of stars that can be obtained from the light we receive
(you can't use the example that came up in class)
web stuff
where/how to
download ds9
(the software necessary for tomorrow's lab)

images for the lab

stellar evolution summary
image processing lab 
image processing lab
 lab due next tuesday?
of the week
direct proof of dark matter?

'Proof of Dark Matter'
(front page, today's
Washington Post)

'Planets Askew in Heavens,
and Here on Earth,
A Mess'

(today's NY Times)

the IAU debate:
is Pluto a planet?
(go to pages 4 and 5
after pdf opens)


'the day we
lost Pluto'
(today's NY Times)

 vote on Pluto is today

the new proposal is to demote Pluto from planethood