What causes the changes in a star?

Answer 1

each star is made up of hydrogen and the source of energy and heat in stars is nuclear fusion of hydogen nuclei into helium at a tempreature of around 6 m celsius.after a particular period when all the hydrogen will be converted into helium then because of intense gravitational pull the star will begun to collapse under its own gravity and at a particular tempreature again the fusion of helium into lithium starts this phase of sun is known as white dwarf. if the weight of any star is equivalent to the mass of our sun then that star will enter into white dwarf phase after red giant phase, and if the mass of staris more than the mass of sun then after redgiant phase star will change into neutron star or pulsar and then finally end up as blaack hole.for e.g black hole observed in sirius constellation 100 light years far from earth

Answer 2

small stars like our sun will die because the molecular fusion inside of them will increase for a while, increasing the sun's mass, then gravity will overpower the sun and crush it into a white dwarf star. big red supergiants like Betelgeuse will have a huge gravitational force, fusing not just H into He, but He is fused into Be and that is fused into O which is fused into S which is fused into Fe which is so heavy that it kills the star in a supernova leaving only a neutron star.

Answer 3

The stars dies when it runs out of helium and either causes supernova or becoming a white dwarf.