A star is born when fusion begins in its core. It is automatically considered a main sequence star. Majority of a star's life is spent as a main sequence star. The Sun has been on the main sequence for about five billion years and will remain for a predicted five billion more years before it becomes a Red Giant Star.
Once a star on the main sequence has used up its hydrogen, it transitions from a main sequence star to a red giant star. It expands in size and, depending on its mass after expansion, will eventually become a white dwarf, neutron star, or black hole.
When a low-mass star enters the Red Giant phase, its outward pressure exceeds the gravitational pressure and the outer layers of the star will begin to merge with interstellar space. It creates a planetary nebula, and all that will remain of the star is the remnant of the star's core. This smoldering ball of carbon is a White Dwarf.
When a high-mass star reaches the end of its life, it undergoes a supernova explosion and the outer layers of the star are driven outwards. All that is left behind is its extremely dense core. This can result in a neutron star or, in a very high-mass star, a black hole.
Once a star on the main sequence has used up its hydrogen, it transitions from a main sequence star to a red giant star. It expands in size and, depending on its mass after expansion, will eventually become a white dwarf, neutron star, or black hole.
When a low-mass star enters the Red Giant phase, its outward pressure exceeds the gravitational pressure and the outer layers of the star will begin to merge with interstellar space. It creates a planetary nebula, and all that will remain of the star is the remnant of the star's core. This smoldering ball of carbon is a White Dwarf.
When a high-mass star reaches the end of its life, it undergoes a supernova explosion and the outer layers of the star are driven outwards. All that is left behind is its extremely dense core. This can result in a neutron star or, in a very high-mass star, a black hole.