Astrophysics trimester 3 2005 class assignments

 syllabus   &   important stuff &   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  

May 16
May 17
May 18
May 19
May 20
Monday, May 23
 last JIT of the year
final project presentations at 6 pm

please arrive 5 - 10 minutes early, or else we may need to return at 8:30 pm?
(always done before class)
today we talk about degeneracy
(not very much about it in your text), which is the key to understanding stellar death

red giant evolution

investigate planetary nebula
evolution (see pictures and links below)
follow the energy:
of the supernova explosion:
where did the energy come from?
(1 source)

where did it go?
( 6 sources)

bring a list of ways in which supernova 1987A was a first or of otherwise importance to astronomers

bring a list of the top 5 forms of energy left after the explostion and the 1 energy present before the explosion (that turned into all the energies after)

even better, bring a calculation (or two!) of those energies above
how did we discover neutron stars?

if you had discovered a regularly pulsing (flashing) source with a
(very regular) period of about 1 second -- like Jocelyn Bell, you might think that you had discovered a signal from aliens... how would you decide if it was an intelligent signal or just something astronomical?

what are they like?

type Ia SN
 happen in binaries


have you firmed up your final project?
questions for class:

what's the 3rd assumption made in deriving the ideal gas law?

what force pushes the planetary nebula away from the star? (or, equivalently, what transfers momentum to the planetary nebula?)

how do planetary nebula shapes evolve?

what do the electrons in a completely degenerate gas move fast?
(remember that you can't say 'because it's hot')

why do the more massive stars go on to more rounds of fusion than the low mass stars?
(or in other words, why dont they become degenerate and, therefore, die?)

see energy questions about supernova above?

web stuff
  Introduction to white dwarfs

  white dwarfs and electron degeneracy

the evolution of planetaries:

the youngest known PN, the Stingray, is only 20 years (!) old

NGC 7027 has a plane of dust (perhaps due to a binary companion?) & concentric rings in the gas shell

the Egg (visible) was the first to show jets!! there's also a faint dust disk perpendicular to the jets

 the Egg (ir); the dust disk is much easier to see in the infrared

the Butterfly has a pinched hourglass shape perhaps due to a binary companion

another Hourglass one from a different perspective

a hubble cartoon shows how these hourglass nebulas are  shaped by a binary companion

the Cocoon shows what a PN will look like after the nebula stars to dissipate

the Helix  is a mature planetary,
1.5 c-yr in diameter

supernova implosion and explosion movies
(best movies are the ones at the very top)

the crab pulsar: on and off

Crab Nebula: The Movie

Crab Nebula: The Pulsar Wind


news & discoveries
 the Sombrero in IR
and even more about planetaries:

a great place to start
Introduction to planetary nebulas

a great variety of shapes
Planetary Nebulae Images

Hubble Space Telescope Planetary Gallery

 Hubble Captures the Shrouds of Dying Stars

May 9
May 10
May 11
May 12
May 13

know the specific names of objects that are in the process of forming stars
 bring to class calculation (on pater to hand in) under homework below

think about & decide final project (with partner)
(always done before class)
 look at the pictures of starbirth and read the captions in "web stuff" column below

find out how the protostars cooled off BEFORE they became protostars (not WHILE they are protostars!),  since we didnt do so well on that question in friday's JIT... the answer is IN last friday's reading!  section 20(7)
find some figures/pictures in your text that match the phases of stellar birth evolution listed on page 25 of the blue book 
 20(6), the last section in the starbirth chapter

7(9) on extrasolar planets & the page "Alien Planets" just following it; then read the extrasolarplanet summary below; take some notes, so that you can intelligently about the different groups of extrasolar planets and how they got to be the way they did

also helpful:
4(8) & box 9-1 on the origin of tides and 9(5) on lunar migration and the origin of the moon

it would also be nice to pick one of the "this just in" weblinks under wednesday and read a short bit about it and come to class with both questions and descriptions

read the article "A decade of brown (dwarfs)" from May 2005 Sky and Telescope
(you got a photocopy yesterday; it's also on reserve in the library)

in conjunction with

the blue book pages 31-32 (which I wrote 2 years ago)... what's wrong, what's right, what's new?

due tonight:

pick a nuclear reaction (NOT one that is done in Walker)
1) write the reaction showing that it obeys the 3 conservation laws that involve quantized quantities

2) find the energy released in the form of kinetic & light
(make sure that you use the standard problem solving method of conservation of energy that i used in class

also, remember that the masses in appendix E are for neutral atoms, and not nuclei, as are the things in your reaction... so remember to take care of electrons properly, as I did in class)

3) find the efficiency of your reaction
for your object (Barnard object, Bok globule, etc.)

1) state the mass, radius, and temperautre
(and tell me where you got the info from)

2) find the
a) gravitational energy
b) kinetic energy
c) total energy of  your object

3) from your answers,
predict whether your object should be contracting, static, or expanding
(this of course should fit with what you know the object is actually doing!)

dont forget to check units... and tell me your object's type/name!!!
(I wont remember what group you're in)

in the blue book, page, p. 26, IGNORE the last column in the table MJ !
the useful column is the second last column, which is the mass in solar units

have you done the homework in the
"reading" box under tuesday?

web stuff
  molecular clouds & cooling

the GMC at the heart Of Orion

Milky Way Molecule Map

Dark Bok Globules in IC 2944

JPL press release on first GMC caught in the act of collapse
( the NY Times article Oct. 10, 1995)


star formation:

star formation propagation
(grav collapse induced by shock wave from O/B stellar winds)

M16 before hubble
 Star-Birth in M16
the Eagle in 2005

shock-wave triggered starbirth
Hubble presents a family portrait of a parent and 6 offspring

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

  cloud-cloud collisions:

a bow shock near LL Orionis

galaxy collisions
the Antennae:
visible and infrared and x-ray

how stellar disks form and evolve
(theory in pictures)

the first observations of jets and disks during stellar birth 

stellar Disks and Jets

  12-c-yr long jets

Stellar Disks Set Stage for
Planet Birth in New Hubble Images

disks without jets: planet building?:

5 years ago we had 1; now,  hundreds

the original discovery of proplyds in the

Orion Nebula

Orion Nebula Mosaic and Protoplanetary Disks

protoplanets within disks?:

making protoplanets at beta Pictoris

and this just in:

how appropriate: today's Astro Picture of the day is of the first extrasolar planet

signs of an alien asteroid belt



interstellar sugar provides clue to origin of life

summary of extrasolar planets properties

 brown dwarfs, planets, and superplanets

an updated version of the blue book pp. 31-32

the brown dwarf smoking gun gif

news & discoveries

red speck is indeed a new giant planet

X-ray Super-Flares Aid Formation of "Solar Systems"

 birth of a black hole?

May 2
May 3
May 4
May 5
May 6
jit due
by 1 pm 
(always done before class)
Weighing in on the
neutrino mass article;
finish worksheet at the end of the  canary handout
the sudbury data:
what does the sudbury experiment add to our knowledge about the solar neutrino problem?

are there other experiments that we need to do that would put more nails in the coffin (of solving the solar neutrino problem),
or is it over?

Univers 21(1), including boxes 21(1&2) UP TO the bottom of the left column on page 482...
(bring the answers to class tomorrow):
a) what is wrong with their main-sequence-lifetime calculation in box 21(2)?
(hint: Toan will not be in class tomorrow to remind us)

b) the fraction f in the first equation of box 21(2) actually stands for a product of 3 separate numerical fractions;
what are each of the fractions (expressed both in words and then as a number)

c) in section 21(1) and the  associated boxes, it is claimed that massive stars have shorter lives than less massive stars...

but how do we KNOW (i.e., from observations) that this is true? (and the answer isnt that we just sit around and watch massive stars and non-massive stars evolve and see which dies first... why not?)
18(2) and finish reading section 21(1)
[Walker on energy transfer processes postponed until tomorrow]

questions for today:

a) leftover from yesterday:

in section 21(1) and the  associated boxes, it is claimed that massive stars have shorter lives than less massive stars...

but how do we KNOW (i.e., from observations) that this is true? (and the answer isnt that we just sit around and watch massive stars and non-massive stars evolve and see which dies first... why not?)

b) ultimately we want to know how the red-giant lifetime of the sun compare (ratio!) to the main-sequence lifetime of the sun...

to answer, you will need to know what the energy sources are in the red-giant phase (remember, I already talked about this in class; hint: there are 2)

and then,
the 3 fractions that correspond to these energy sources
(i just want you to know/bring the fractions to class, although if you want to go farther and actually find a number that's ok too)

c) what are the 3 sources of pressure that can be used by a star to push out vs. gravity?; be able to write down a law or describe the source of the pressure qualitatively
(use your knowledge of chemistry, your cultural literacy, and your personal experience)

see questions remaining from yesterday's column on pressure... plus,

d) why does the pressure have to increase as you go toward the center of the sun?

e) how should one write the ideal gas law (yeah, that one from chemistry)?:
which variable(s) should be on the left side and which variable(s) should be on the right side?
(and what decides "sides" anyway?)


walker 16(6) on the 3 mechanisms of energy transfer:

what are the 3 energy transfer mechanisms that move energy from the core to the surface and how do they work?

which of these happen in the sun?  in what portion of the sun?  how long do these processes take?

don't concern yourself too much with the fancy equations in walker, but mostly with being able to describe what is happening qualitatively

also, begin chapter 20 for friday?
20(1-3,7,8) on starbirth

convection near and far:

convection in the kitchen: p.182

convection in the earth's liquid core:

plate tectonics in the mantle: p.189

convection cells and winds in Earth's atmosphere, p. 197

circulation cells in Venus' atmosphere, p. 247

convection in Jupiter's atmosphere, p. 291

convection in the solar photosphere,
p. 401

convection in protostars, p. 462

convection (dredge-up) in red giants, p. 503

see above

possible final projects

web stuf

the superkamiokande detector before it was damaged by a freak chain-reaction process

damage to the SK detector
on 11/12/01

the first neutrino image of the sun

two nice (but longish) articles from the Nobel prize archives:

How the Sun Shines

the Mystery of the Missing Neutrinos

 images from the neutrino article handed out last week
(one of the experiments that shared the
nobel prize in physics 2.5 years ago)

ramping up in minnesota:
Tiny, Plentiful, and Really Hard to Catch

news & discoveries

Deep Impact spots its comet

Wonderful star reveals its hot nature

Hubble Celebrates 15th Anniversary with Spectacular New Images

astro pages for  April 2005
astro pages for March 2005