SORU: aşağıdaki parçaya göre cevaplayınız
As it is pointed out in the passage, stars —.
Stars are believed to begin life as collapsing masses of hydrogen gas, which are called "protostars". As collapsing masses start contracting, they heat up. When the temperature in them reaches 1 o million degrees, nuclear fusion begins and forms heavier elements, mainly helium at first The energy released during these reactions balances the gravitational force, and the young star stabilizes as a main-sequerce star. T"e tremendous onghtness of stars comes from the energy released during these thermonuclear reactions. After billions of years, as helium is collected in '.he core and nydrogen s usee up, the core contracts and heats further. The envelope expands and cools, and the star becomes a red giant. The next stage of stellar evolution depends on the mass of the star. Stars of residual mass less than 1.4 solar masses cool further and became white dwarfs, eventually fading and going out altogether. If the star's residual mass is greater than two or three solar masses, it may contract even further and form a black hole, which is so dense that no matter or light can escape from it.