Name ______
Chapter 13 Homework
1.What is parallax?
2. What do we use as a baseline for Parallax measurements to determine the distances to the nearest stars?
3.What term do we use to describe the relative brightness of the stars?
4.Star A and Star B have same temperatures, but Star A is more luminous than Star B. Based on this information, what is the most obvious reason for this?
5.What does Luminosity (absolute brightness) of a star depend on?
6.Which of the following stars has the hottest stellar surface temperature?
M9, A0, G2, A5, K9
7.Which of the following stars is reddish in color?
M9, A0, G2, A5, K9
8.In the HR diagram on the x-axis the temperature increases how?
9.In the above HR diagram sketch, which star is a white dwarf?
10.In the above HR diagram sketch, which star is a red dwarf?
11.In the above HR diagram sketch, which star is a red giant?
12.In the above HR diagram, which main sequence star is bluish in color?
13.In which binary system can we observe both the stars separately and follow their orbits around each other?
14.The star Aldebaran is a red giant, and is much more luminous than the Sun. What conclusions can be drawn from this fact?
15.The star Aldebaran is cooler and much more luminous than the Sun. Where do you expect to find Aldebaran in the H-R diagram?
16.How can we explain the fact that hydrogen Balmer lines are essentially absent in the hot O type and the cool M stars?
17.Why are binary star systemsvery important?
18.What is the difference between spectroscopic and visual binaries?
19.Why do stars on the main sequence have different luminosities?
20.What can we conclude about a star because its luminosity varies in an irregular pattern?
21.Star A has an apparent magnitude of 2, Star B has an apparent magnitude of 1. Which star is brighter and how man times brighter is it?
22.The H-R diagram usually graphs the stars according to their luminosity and temperature. An equally valid H-R diagram could be done by plotting what?
23.The hydrogen absorption lines are the strongest in which type of stars?
24.A main sequence star has 2 times the mass of the Sun. Using the mass-luminosity relation how many more times luminous is this star than the Sun?
25.How do white dwarfsspectral lines compare to red giants.
26. The star Rigel radiates most strongly at about 200 nanometers. How hot is it?
27. Sirius has a parallax of 0.377 arc seconds. How far away is it?
28. The parallax of Proxima Centauri is about 0.763 arc seconds. How far away is it?
29. Two stars in a binary system have an orbital period, P, of 2 years and an orbital separation, a, of 4 AU. What is their combined mass?
13-1