____ 44. Two stars are found to have the same spectral type, K7. However, one star is 16 times as intrinsically luminous as the other. From this information, what can you determine about their radii?
____ 45. Measurements indicate that a certain star has a very high intrinsic brightness (100,000 times as bright as our Sun), yet is relatively cool (3500 K). How can this be?
____ 46. Brown dwarfs areA) stars made almost entirely out of brown dust.B) objects with masses too small to sustain thermonuclear reactions and be considered stars.C) old stars, contracting after using up all of their available hydrogen fuel.D) stars that lie between types O and A.
____ 47. The two stars in a binary system have masses of 1 solar mass and 4 solar masses. The semi-major axis of their relative orbit is 5 AU. What is the period of their orbit around each other?
____ 48. Two stars in a binary system orbit each other such that star A is 2 AU from the center of mass of the system and star B is 5 AU from the center of mass of the system. If the mass of star A is 10 solar masses, then what is the mass of star B?