Chapter 16 Flashcards
How far is the sun from the milky ways center
2/3 from the center
What type of galaxy is our galaxy
A spiral galaxy
What are nova and supernova called
Cataclysmic variables
What are stars who’s luminosity varies in a regular way but more subtly
Intrinsic variables
What are the two types of intrinsic variables
RR Lyrae stars and Cephids
What is the period of luminosity for lyrae stars
0.5 to 1 day
What is the luminosity period for a cepheid
1 to 100 days
How do we measure the distance to RR lyrae stars
They all have about the same luminosity, so knowing their apparent magnitude lets us calculate the distance
How do we measure the distance to Cepheids
They have a luminosity that is strongly correlated with the period of their oscillation, so once we know that period we can calculate the distance
Where are RR lyrae stars mainly found
In globular clusters
What are star clusters
They are groups of stars bound by gravity
What are the two types of star clusters
Open clusters and global clusters
Do stars near the center or the edge of the galaxy move faster
Near the center.
How fast does the sun and its neighbors move around the center of the galaxy
At 220 km/s
What is the galactic halo
It is essentially spherical, the stars in it are very old and it has no gas or dust
What is the galactic disc
It is where the youngest stars are, as well as star formation regions, large clouds of gas and dust
What is the galactic bulge
It surrounds the galactic center and has a mix of older and younger stars
How are orbits in the disk
They are in the same plane and in the same direction
How are orbits in the halo and Bulge
Much more random
How do we determine the milky ways mass
Keplers third law, we use the suns distance to the center and its period of revolution. It is 10^11M
What does the orbital speed of an object depend on
The mass between it and the galactic center
What is dark matter
It is the material that is predicted to account for the discrepancy between keplers third law and the mass observed in the form of gas and dust
How old are the galaxies most ancient stars
13 billion years old
How large is the galactic centers black hole
3.7 million solar masses
