Intro to Astronomy summer 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  

August 7
August 8
August 9
August 10
August 11

no class
final exam,
2 - 5 pm
(always done before class)

galactic violence:
how the universe
will end
the Big Bang;
how the universe began

questions you should be able to answer after you've done the reading

what are the competing theories of galaxy formation and evolution?

are there genes that decide E or S?

what environmental conditions favor E or S?

what is the evidence for dark energy?

how is dark energy different from dark matter (or bright matter)?

what is the geometry of the universe?

what is the likely future of the universe: expand forever?  collapse on itself?

how secure is our understanding of the future?

what evidence is there for the Big Bang?

is it circumstantial or ??

what happened during the main events in the first hour:

the inflation era?
the pair creation era?
the fusion era?
the radiation-dominated era?
the matter-dominated era?
the moment of decoupling?


homework 5
homework 6  now posted

web stuff
components of the Milky Way

a new closest galaxy: the Canis Major dwarf

the Sagittarius dwarf

(discovered only in the last decade) is living inside the Milky Way

Milky Way Past Was More Turbulent Than Previously Known

the oldest objects
in the galaxy

Star Formation Peaked Later than thought

deepest view ever unveils earliest galaxies

Hubble Sees Early Building Blocks Of Today's Galaxies

Hubble Identifies Primeval Galaxies

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)

inventory  of the universe

the Millenium Cold Dark Matter simulation

WMAP views the 3K background

Beyond the Big Bang
(" countless replicas of Earth, inhabited by our clones, are scattered throughout the cosmos...)

news & discoveries

July 31
August 1
August 2
August 3
August 4

test emphasizes
binary stars through stellar evolution
(done before class)

finish chapter 22:
how massive stars die: the supernova phenomenon
24 (and 23 if you didnt read it for yesterday)
25 and 26
[you should have already read  sections 25(4-5) and 26 (1-5)]

questions you should be able to answer after you've done the reading

what decides how a star dies?
(what stellar property, what "event")

what triggers the supernova explosion?

why does the onset of complete degeneracy signal the end of a star's active life?

why are supernovas important to your existence?

why was supernova 1987A so important to astronomers?

why don't all supernova remnants contain pulsars?

why aren't all pulsars surrounded by supernova remnants?

what's the difference between type I and type II supernovas?
(which type have we been discussing in class?)

what 5 things would you have done to decide if the LGM phenomenon was an astronomical object or the communication from some extraterrestrial civilization?

what are the only 3 properties that black holes can have?

what is the event horizont?

what is the singularity?

how do we think the Milky Way formed?

what are population I and II objects, and how are they different?

how does the origin theory of the Milky Way explain these differences?

what's the difference between elliptical galaxies and spiral galaxies?


homework 4
(assignment 5)

web stuff
red giant and planetary nebula evolution

supernova events

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

the crab pulsar: on and off

Crab Nebula: The Movie

Crab Nebula: The Pulsar Wind

pulsar physics

type Ia SN
 happen in binaries

Falling into a Black Hole

Laser Interferometer 
Gravitational-Wave Observatory
your tax dollars at work

components of the Milky Way

a new closest galaxy: the Canis Major dwarf

the Sagittarius dwarf

(discovered only in the last decade) is living inside the Milky Way

Milky Way Past Was More Turbulent Than Previously Known

the oldest objects
in the galaxy

Star Formation Peaked Later than thought

deepest view ever unveils earliest galaxies

Hubble Sees Early Building Blocks Of Today's Galaxies

Hubble Identifies Primeval Galaxies

news & discoveries
lakes on Titan?

July 24
July 25
July 26
July 27
July 28
(done before class)

assuming you have finished reading 18(1-4);
new = essay on "searching for neutrinos ... " at end of chapter 18

finish chapter 18
on the outer parts
of the sun

chapter 20
[remember that you have already read section 20-2]

starbirth steps

starbirth summary table
21(2,3) on stellar old  age

22(1-4) on the death phase of stars like the sun

25(7) on spiral shock waves
"next-day" assignment; bring completed to class
1) what would the power in the mass-luminosity relation (in other words, what is p in Luminosity  =  Mass^p  or Mass raised to the power of p) have to be in order that the least massive stars were also the shortest lived (and the massive stars were the ones to live the longest?)  explain.
(yesterday's reading in chapter 21 should be helpful)

(is there more than 1 answer?)

2) how do we know -- just from observations, not theory --  that the O stars live the least long of all the stars and that the M stars are the longest lived?  

after all, we have never seen a single star leave the main sequence (and evolve to become a giant/supergiant because it ran out of hydrogen in the core)

  stars' main sequence lifetimess are millions of years at least -- we won't see one leave the main sequence in your lifetime either!

see email that i sent wednesday afternoon, 2:15 pm

questions you should be able to answer after you've done the reading

what is the source of energy of the sun (and all main sequence stars?
(i.e., what form is the energy in before it is light?)

why do we think hydrogen --> helium fusion is the energy source at the cener of the sun, even though we apparently can't "see" this happening?
(4 separate answers here!)

what property of a star determines its lifetime?

why can neutrinos tell us that nuclear reactions are occurring in the sun's core?

how can we be sure that the neutrinos we detect are coming from the sun (and not from somewhere else)?

how did sunspots get to be cool?

ow does the energy generated via nuclear fusion reach the surface? (by what processes)

why does the energy leave the center and reach the surface?a star's life is a long-term fight between the pressure forces pushing outward and gravity pulling inward...what causes an intersellar cloud to begin the collapse toward starhood?

in what part(s) of the spectrum do astronomers have to look to see starbirth? why?

the H-R diagram on p. 450 shows the evolution of pre-main-sequence stars on their way to the main sequence... what part of stars' pre-main sequence evolution did they leave out? why do you think they did that?

notice that the times given for pre-main-sequence evolution on this H-R diagram are much shorter than for main-sequence evolution.... why is that?


homework 3
(assignment 4)
due today

homework 4
(assignment 5)
due tuesday
web stuff

the active sun in the ultraviolet

close-up of magnetic coronal loops

the magnetic corona

a typical coronal hole

hear the sun quake

see what helioseismology tells us

see the sun quake

the most amazing coronal mass ejection
(plus see a comet swallowed)

Seething Sunspot

the solar magnetic carpet

sunspot loops in the UV

CMEs on the active sun

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

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)

Stellar Disks Set Stage for
Planet Birth in New Hubble Images


the original discovery of proplyds in the

Orion Nebula

interstellar sugar provides clue to origin of life

statistics of exoplanets

jk's summary of extrasolar planets properties

brown dwarfs, planets, and superplanets

the brown dwarf smoking gun gif

news & discoveries

July 17
July 18
July 19
July 20
July 21
(always done before class)

H-R diagram leftovers:
19(8): how do you tell the difference between a main sequence, giant, and
white dwarf star spectroscopically?

[from last friday: 26(1-3,5)]
new 26(4): how we get distances to galaxies?
[please do not read
box 26-2!!]

Kepler's 3rd law
(plus his other two laws, where it came from, and why it's equivalent to the law of gravity):
4(3-7), particularly
boxes 4-2 and 4-3

spectroscopic, eclipsing, and visual binaries:
how astronomers get masses

one more example of the doppler effect:
finding the mass of a galaxy: 25(4), including box 25-2

18(1), the beginning of "how stars work"


stellar structure,
and energy transfer
assignment to bring completed to class

after reading box 26-2: why does the interpretation of a galaxy's redshift as a recession velocity from us (in a universe of finite age, the time since the Big Bang) violate the "no one is special" principle?

for the yellow handout in class today:

1) which star (A or B) is more massive? 
2) by how many times?
3) which star is eclipsed at
phase = 0? how did you know?
(hint: think about how the stars are moving right before and after the eclipse at phase = 0)

questions you should be able to answer after you've done the reading
what are the main classes of galaxies?

what do galaxies contain?

how do we know that the universe is expanding?

what is the implication of Hubble's observation that the furthest galaxies are moving away from us the fastest?

how do we get distances to galaxies so that we can plot a Hubble diagram?

be able to distinguish between various book versions  of Kepler's 3rd laws

how astronomers find the masses of stars in a binary system

how is Kepler's 3rd law used to find the mass of a galaxy?

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 did the temperature get to be so high at the center of the sun?

Why does the temperature and density need to be high for fusion to occur?

homework 2
(assignment 3) due

web stuff
I did not make up buckyballs

shock waves from bullets and jets

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

the spectroscopic binary applet

the eclipsing binary applet
HD 209458 velocity curve

HD 209458b transit

first image of an extrasolar planet

Cygnus X-1 velocity curve: first case for a black hole

typical MACHO micro-lensing event

typical macro-lensing behavior due to galactic-scale
dark matter

for your leisure reading: 

are periodic extinctions 
  statistically real?  a Scientific American debate

The Great Dying: the
buckeyball evidence

news & discoveries

July 10
July 11
July 12
July 13
July 14
(done before class)
7 (6-7)
19 (1-3_&
boxes 19(1-3)
boxes 19(2-3)

5(7-8): line spectra & energy levels
start with 5(7-8) [unless you are already read it for yesterday]

19(5-7) on spectra and the H-R diagram
still working on 19(5-7)
20(2): red nebulas, blue nebulas, and fluorescent lights

5(9): the Doppler effect

26(1-3): what's a galaxy?

26(5): the expansion of the universe and how we know that the universe had a beginning

questions you should be able to answer after you've done the reading

the handout on planetary temperatures

how do we know how old the solar system is?

how did the (2) major "events" (planetary melting/differentiation and the bombardment era) that occurred after planetary formation change the face and interiors of the planets?

how do astronomers find the distance to a nearby star?

what does apparent magnitude measure?

what does absolute magnitude measure?

what are the two basic rules of magnitudes?

why does the existence of energy levels explain why transparent gases have line spectra?

why do opaque gases have continuous spectra?

what happens in fluorescence?

why are hydrogen lines strong (dark) in A stars
(of temperature 10,000 K)?

why [in terms of the hydrogen energy level diagram -- see 5(8)] do the hydrogen lines get weaker in cooler stars?
in hotter stars?

why are lines due to neutral metals (such as Fe, Na, Ti, Ca) very strong/dark only in cool stars?

why are lines due to helium very strong/dark only in the hottest stars?

why are red fluorescing nebulas ONLY found around the bluest stars?


collective list of answers to the "list of 10 properties of stars to find from spectra"

homework 1
due today

homework 2
(assignment 3)
due next tuesday

web stuff
evidence for ancient  life on Mars ?

meteorites we saw in class

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
 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

fluorescing H II regions in the M51 galaxy help us trace the spiral arms and places of recent stellar birth

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)]

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?)

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

spectrum of
an A0V sta

spectrum of a G2V
(sun-like) star

doppler effect applet

July 3
July 4
July 5
July 6
July 7
(always done before class)


know the  three basic types of spectra and what physical states of matter produce them
light: behavior & characteristics

5(3-4);  be familiar with the 2 blackbody laws
(Wien's and Stefan's)

box 5-2 examples: be able to distinguish between luminosity and flux

finding the radius of a star:
box (19-4)

intro to planets:
7 (1 - 5)
the solar system's planets can be divided into two classes: what are the names of these 2 classes are what are some properties that distinguish these two classes of planets?
how the planets got their properties: the formation of the solar system:

8 (1-5)



questions you should be able to answer after you've done the reading

what are the 3 ways that a hotter blackbody curve differs from a cooler blackbody curve?

what does Wien's law relate the temperature of a star to?

what does Stefan's law relate the temperature of a star to?

how do Wien's and Stefan's laws show up on the blackbody curve graphs?

what is a blackbody, anyway?

what are the units of flux?  of luminosity?
what else is different about them?

what instruments can measure flux?

(how) can luminosity be measured?

what are the
basics of our
"condensation-accretion" theory) of how the
planets formed and
acquired their

which came first,
condensation or accretion,
in planetary formation?

what were the major events that occurred in planetary history after planetary formation?

how do we know how old the solar system is?


to hand in:
10 properties (of stars) to find from spectra due in class today

to think about
(not to hand in):
based on the physical state of a fluorescent light bulb, what type of spectrum would you predict the light would have?

homework 2

due tuesday,
July 11

blackbody applet for homework

(the applet requires java, so that must be enabled on your computer; if you can't find a computer that it works on, let me know)

clicking on the link above should open 2 new windows -- be patient... it could take 30 seconds -- a useless one and one containing intensity/wavelength axes; in this window, click on the "blackbody" button to add a blackbody, type in the temperature below the thermometer, and you'll find the %s emitted in uv. vis, and ir in another new, tiny window that opens

image processing lab due
web stuff

intro to image processing lab

images for the lab

stellar evolution summary

and how they work

Line Spectra of Fireworks   
The Physics of Colored Fireworks

10th (?) planet
 discovered last year

the status of the Voyager satellites
news & discoveries
summer discovery highlights:

two dust disks
(& a planet?) around nearby star

black hole paradox answered


what we did
in class
saw examples of different types of spectra (continuous, bright-line, and dark-line)

what astronomers can observe and what they can deduce
what flux means and how astronomers measure it

the image processing lab:
how astronomers manipulate data
what blackbodies are and why stars are good blackbodies

the first blackbody law:
Wien's law &
how the color of a star is determined by its temperature

why the sun looks yellow even though it's really blue-green
(effects of the eye sensitivity and scattering by the sky)
the second blackbody law: Stefan's law: how the flux in a blackbody is determined by temperature

differences between flux and luminosity

the differences between terrestrial and jovian planets
measured the luminosity, radius, and temperature of the sun using only a meter stick, a 200-watt light bulb, and a wax photometer

the condensation-accretion theory of planet building

why condensation is necessary for accretion

what determines the temperature of a planet

how temperatures in the proto-planetary disk around the sun determined the composition, size, mass, density, etc of the planets