Stars of different masses have varying life spans, with the more massive stars “burning out” more quickly than stars of lower masses. How or what they do when they burn out also varies, depending on the mass of the star. All stars are called main sequence stars as they continue fusing hydrogen and staying in a state of equilibrium—a balance between gravity and thermal pressure. However, when stars stop fusing hydrogen, they undergo changes that will lead to their eventual death. Once again, a star’s mass determines how long it will last.