Astr 104, Spring 2008 – Quiz 4

1. For which stars can we use the parallax method to find their distance?
a. The nearest ones, out to several hundred light years.
b. The brighter ones, up to apparent magnitude 2.
c. The ones for which we can obtain a good spectrum.
d. All stars that we can see with our telescopes.

2. Which of these stars is nearest to us?
a. Sirius.
b. Betelgeuse.
c. Alpha Centauri.
d. Polaris.

3. Can we find how fast a star is moving if we don't know how far it is from us?
a. Yes.
b. Only the sideways speed, but not the radial one (towards or away from us).
c. Only the radial speed (towards or away from us) but not the sideways one.
d. No.

4. Can we see the size of a star on a photograph taken with a telescope?
a. Yes, large telescopes magnify images enough for us to see the size of most stars.
b. Yes, we can find the size from the brightness of the image on the photograph.
c. Yes, we can find the size from the color of the star's image on the photograph
d. No, the image on a photograph is not enough, we need more informaton.

5. What is the difference between the absolute and the apparent magnitude of a star?