Question

Which stage is attained by the star after the steady state? Explain that stage.

Answer 1

Hint: Red star stage of star is the later stage after the steady state of star. In this stage the star evolves into a giant red star or supergiant where it appears red hot because of the thermonuclear fusion of hydrogen in a shell surrounding the core.

Complete step by step solution:
The stage attained by the star after the steady state is the red stage, in this stage the star reaches a stage where temperature is high enough that the core starts fusing hydrogen and gradually converting into helium with helium start burning to carbon for a couple of million of years until, eventually, the helium runs out. Its outer atmosphere is inflated and tenuous making its radius several times larger than that of our Sun, and the surface temperature is usually around 5000K.
The stages are evolved in following steps:
1. When the initial star stage reaches its main sequence stage, the core becomes hot enough that the fusion of hydrogen takes place and establishes a hydrostatic equilibrium.

2. Main-sequence stars that have masses in the range from around 0.3 solar masses to around 8 solar masses start evolving to the first red giant stage due to gradual loss of all the radiation .

3. Over a star’s main sequence life, it slowly converts hydrogen in the core to helium. A star’s main sequence life ends when nearly all its hydrogen supplies in the core have been fused.

4. Due to the degeneration of the core temperature becomes high enough that fusion of helium to carbon takes place via the triple alpha process.

5. An analogous process occurs when the central helium is exhausted and the star collapses once again, causing helium in a shell to begin fusing.

6. At the same time, hydrogen may begin fusion in a shell just outside the burning helium shell, which puts the star onto the asymptotic giant branch, a second red-giant phase.

7. At the end of its second phase, the star will eject its outer layers, forming a planetary nebula, and having its core exposed, ultimately becoming a white dwarf.

Note: Red giants stars remain in this stage from a few thousand to 1 billion years. They eventually run out of helium in their cores and thus fusion stops.