Author Question: Good tracers of the spiral arms of our galaxy are all I. very old. II. very young. III. very ... (Read 61 times)

JMatthes · **on:** Jul 27, 2018

Good tracers of the spiral arms of our galaxy are all I. very old. II. very young. III. very luminous. IV. moving with large radial velocities.

a. I & III
b. I & IV
c. II & III
d. II & IV
e. I, III, & IV

Question 2

What measurements are needed to determine the orbital motion of a spectroscopic binary star?

What will be an ideal response?

reversalruiz · **Reply #1 on:** Jul 27, 2018

Answer to Question 1

c

Answer to Question 2

Measure the spectra of the binary system over time and determine the Doppler shifts of the spectral lines from each star.