1. The problem statement, all variables and given/known data consider the information given below about three main sequence stars. Star 1 will be a main sequence star for 4.5 billion years. Star 2 has a spectral type of M5. Star 3 has the same luminosity as the Sun. Which has the greatest mass or are they approx. the same? 2. Relevant equations 3. The attempt at a solution Spectral class M5 tells me that the star is cool, dim, and small. I know that the sun has been on main sequence longer than 4.5 billion years and will remain on it longer than that. I know that the life time of a star is related to their mass. So after pondering the question i believe the answer is Star 1 b/c it will have a shorter life span than star 2 and 3 which to me indicated it is a relatively more massive star. Though is my thought process correct? Could stars 1, 2, and 3 all have approx the same mass? any help would be great thanks pf!