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CHAPTER 15
from book and outline paper
38
Astronomy
Undergraduate 1
05/05/2009

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Cards

Term
Almost everything we see in the sky belongs to what?
Definition
the milky way
Term
TRUE OR FASLE: early attempts show the sun at the eenter of the milky way
Definition
true
Term
three reaons why is it diffucult to determine the structure of the milky way?
Definition
1.we are inside
2. distance measuring is hard
3. Our view is obstructed
Term
What is the name of a group of young clusters of recently formed stars, within disk of galaxy?
Definition
Open clusters
Term
What is the name of the old, centrally concentrated clusters formed in a halo around galaxy?
Definition
globular clusters
Term
How many globular clusters is the milky way known to have?
Definition
200
Term
What exists at the center of the galaxY?
Definition
the nuclear bulge
Term
What extends outward?
Definition
a flat disk
Term
what is the galaxy surrounded by? what is it filled wiht?
Definition
a halo, filled with globular clusters
Term
What classes are the most luminous stars? short or long lived?
Definition
O and B. Short
Term
What kind of orbits do disks have?
Definition
circular orbits
Term
What kind of orbits do halo stars have?
Definition
elliptical and randomly-oriented
Term
how many years does it take for the sun to orbit the galactic center one time?
Definition
240 million years
Term
What do the rotations of objects in the galaxy follow?
Definition
keplers law
Term
what is the majority of mass in the galaxy called?
Definition
dark matter
Term
do older or younger stars have more metaL?
Definition
younger
Term
What is population I stars? Pop. II?
Definition
POP I: yield absorption lines from heavy elements and located at disk
POP II: yield absorption lines from hydrogen, located in halo
Term
Where are Population II stars located?
Definition
the halo
Term
Where are POPulationI stars located?
Definition
the disk
Term
All elements heavier than ______ are rare.
Definition
Helium
Term
What does hot gas that breaks out of the galactic disk form?
Definition
galactic fountain
Term
what is the total mass in disk of the mIlky way?
Definition
200 billion solar masses
Term
What is used to determine distances to O and B associations?
Definition
cephoid variables
Term
We can observe any direction in the Milky way thanks to....
Definition
radio waves
Term
Neutral hydrogen...
Definition
concentrated IN spiral arms
Term
molecular clouds....
Definition
concentrated ALONG spiral arms
Term
what are spiral arms?
Definition
stationary shockwaves
Term
What is dominant in Grand-Design spiral galaxies?
Definition
spiral arms
Term
What galaxies have spiral patterns but not dominant spiral arms?
Definition
flocculent galaxies
Term
what two things is star formation self-forming due to?
Definition
ionization fronts and supernova shocks
Term
What does the galactic center contain?
Definition
a black hole of 2.6 million solar masses
Term
what kind of xray binaries does the galactic center region contain?
Definition
black hole and neutron star xray binaries
Term
what did scientists conclude about the diameter of the star system?
Definition
it was 10 kiloparsecs
Term
what can the mass of the galaxy be found from?
Definition
its rotation curve
Term
what is nucleosynthesis?
Definition
a process where stars manufacture metals
Term
True or false. The sun is a population 1 star?
Definition
true
Term
What class stars are spiral tracers?
Definition
o and B stars
Term
the halo is made up of population _____ stars and the disk is made up of population ______ stars.
Definition
halo- population II
Disk- Population I
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