ASTR 1020 Exam #3 (Chapters 20-23) April 16, 2009
This summarizes most, but not necessarily all, topics that will be on the exam
Specific topics you should know well:
what are cosmology, the observable universe, galaxy clusters
what are the Hubble Deep and Ultra Deep Fields; what have we learned from them
3 galaxy types and basic properties; what suggests irregular galaxies are forming stars
where do stars form in spiral galaxies; how do the ages of disk versus halo stars compare
the distance chain; standard candles; parallax; relation between brightness and luminosity
how are distances to stars, clusters, nearby galaxies, distant galaxies estimated
why are these standard candles: MS stars (star clusters), Cepheids, white dwarf SNe
Hubble’s 2 important accomplishments: settled distance debate (how?) and Hubble Law
why are galaxies redshifted; what does that mean; what’s the Doppler effect
how does redshift depend on distance; what is the Hubble constant a measure of
value of H0; how can H0 be used to estimate galaxy distances and universe’s age
why Hubble Law implies universe is expanding; where’s the universe’s center, edge
evidence that Milky Way (and probably most galaxies) formed soon after universe did
why must galaxy evolution studies involve studying distant galaxies
how could different initial conditions affect whether a spiral or elliptical galaxy forms
evidence for collisions affecting evolution; why is this more common than star collisions
what are starburst galaxies; what is thought to cause many galactic starbursts
what are AGN and quasars; how bright can they be; why were quasars a mystery at first
what powers AGN; evidence for supermassive BH in Milky Way and other galaxies
what is dark matter; evidence for this in galaxies from what; % visible versus dark
understand differences between rotation curve of solar system and Milky Way
where is dark matter located in galaxies; % visible versus dark in galaxy clusters
3 dark matter estimates in galaxy clusters; what is gravitational lensing; how does it work
what are MACHOs (know examples); why are these unlikely to be the dark matter
what are WIMPs; what does universe look like on the largest observable scales
what is dark energy; how does expansion depend upon dark matter and dark energy
conditions needed for recollapsing, critical, coasting, and accelerating universes
known matter density relative to critical density; what does this imply (ignoring D.E.)
what is the evidence for an accelerating expansion; what was H0 in the past in this case
how does an increasing or decreasing H0 affect age estimates for the universe
big bang concept; why should early universe have been dense and hot
matter / photon production and destruction (constrained by E=mc2)
four fundamental forces; possibility of these unifying at high temperatures
why do we live in a matter rich universe, with little antimatter (don’t struggled to hard!)
how quickly did elements form; when did the universe become transparent
what is the cosmic microwave background; how was it discovered; why only 3 K now
evidence for seeds of structure in CMB; why chemical composition supports big bang
