1. the mass of a star can be determined by a. the wavelength of light emitted by the star. b. the color of the star. c. the distance between the star and earth d. binary star systems 2. a light-year is a. 9.5 trillion kilometers b. 95 trillion kilometers c. 150 million kilometers d. 150 billion kilometers 3. the difference in the brightness of two stars with the same surface temperature is attributable to their a. densities b. colors c. ages d. sizes 4. a hertzprung-russell (h-r) diagram shows the relationship between a. absolute magnitude and apparent magnitude b. temperature and absolute magnitude c. parallax and temperature d. apparent magnitude and parallax 5. which main-sequence stars are the most massive? a. red b. orange c. yellow d. blue 6.