11. Which of the following is the mass and luminosity of a possible Main Sequence star?

a. mass = 1 solar mass, luminosity = 10 solar luminosities
b. mass = 2 solar masses, luminosity = 11 solar luminosities
c. mass = 2 solar masses, luminosity = 0.5 solar luminosities
d. mass = 10 solar masses, luminosity = 1 solar luminosity

Stellar Sizes and Stefan-Boltzmann Law

12. The star Capella is the same color as the sun, but it is much more luminous. What can be inferred from this?

a. Capella is bigger than the sun and has a lower surface temperature
b. Capella is bigger than the sun and has a higher surface temperature
c. Capella is smaller than the sun and has the same surface temperature
d. Capella is bigger than the sun and has the same surface temperature

13. Stars A and B are the same size. The temperature of Star A is twice the temperature of Star B. Which of the following is true?

a. Stars A and B have the same luminosity
b. Star A is twice as luminous as Star B
c. Star A is 4 times as luminous as Star B
d. Star A is 16 (2⁴) times as luminous as Star B

Double Stars and Stellar Masses

For questions 14 and 15: Sirius A is twice as massive as its white dwarf companion, Sirius B.

14. The equation for the location of the center of mass is M₁*R₁ = M₂*R₂. Where is their center of mass?

a. at the center of Sirius A
b. halfway between Sirius A and Sirius B
c. between the two stars, but closer to Sirius A
d. between the two stars, but closer to Sirius B

15. The orbital period of Sirius B is 50 years. What is the orbital period of Sirius A?

a. 25 years
b. 50 years
c. 100 years
d. 200 years