Problem
Set #2
ASTR
3830
A
B
C
D
E
F
G
H
I
- Classify
each of the nine galaxies shown above.
- Estimate
the inclination of the galaxy or explain why you cant in each case.
- In
galaxy B above, you measure the Doppler shift of the 21 cm to be 60km/s at a point near
the bottom of the image. Convert to estimated orbital velocity of the gas.
- You
observe some galaxy spectroscopically and determine its metallicity to be
1.5. What type of galaxy should you
expect it to be, and why?
- A
generic galaxy rotation curve has the velocity rise linearly from 0 at the center to
200km/s at 5kpc from the center. Then it
remains constant at 200km/s out to 15kpc beyond which it cant be measured. a) Make a
plot of M(r), the total mass internal to the radius as a function of radius. Use grams for
y coordinate. b) Make a plot of the density
of the dark matter in g/cc vs radius, assuming the dark matter is spherically symmetric.
- For
the same galaxy described in problem 5, estimate k/w as a function
of radius, where k is the epicycle frequency and w is the orbit
frequency.