the smaller the starting mass of a star is, the longer it will live

In the clouds of dust and gases, nebula. Hydrogen atoms forms a spinning cloud of gas and eventually pulls more hydrogen gas to the spinning cloud. As it spins, hydrogen atoms start to collide with each other and hydrogen gas heats up. When this reaches ##15,000,000^@C## nuclear fusion begins and causes to form a new star or protostar.

Once a protostar forms its life cycle is fixed.

Medium-sized star ##rarr##red giant or super giant

if a star started with a small mass##rarr## main-sequence stars##rarr##white dwarf##rarr##black dwarf

if a star is a low mass red giant##rarr##white dwarf ##rarr##black dwarf (dead star)

if a star is super massive##rarr## super red giant##rarr##supernova very high mass##rarr##Black Hole

if a star is massive red giant##rarr##supernova high mass##rarr##neutron star

Remember that after a supernova, another nebula will form. Neutron stars and blackholes are the core of a star.

http://pics-about-space.com/life-cycle-of-stars-nasa?p=2