1) Suppose you observe a binary system containing a main-sequence star and a brown dwarf. The orbital period of the system is 1 year, and the average separation of the system is 1AU. You then measure the Doppler shifts of the spectral lines from the main-sequence star and the brown dwarf, finding that the orbital speed of the brown dwarf in the system is 18 times greater than that of the main-sequence star. How massive is the brown dwarf?
2) Different regions of the galaxy tend to contain stars of different ages. Place labels for the ages of stars in the correct regions of the galaxy painting.