1. Isolated molecular clouds can have a temperature as low as 12K and a particle density as great as 1.20×105 particlesper cubic centimeter.
Part A What is the minimum mass that a  cloud with these properties needs in order to form astar?
2. Suppose you observe a binary system containing amain-sequence star and a brown dwarf. The orbital period of thesystem is 1 year, and the average separation of the system is 1AU You then measure the Doppler shifts of thespectral lines from the main-sequence star and the brown dwarf,finding that the orbital speed of the brown dwarf in the system is25 times greater than that of the main-sequence star. How massiveis the brown dwarf?
