Question

question: 9 when looking at an h - r diagram, what stage is the star moving into when nuclear fusion begins? hertzsprung - russell diagram

a planetary nebula
b protostar
c main sequence
d super nova

Explanation:

When nuclear fusion begins in a star, it enters the main - sequence stage. The main sequence is the longest - lived phase of a star's life. During this stage, hydrogen is fused into helium in the star's core, and the star is in hydrostatic equilibrium (the inward force of gravity is balanced by the outward pressure from nuclear fusion). A protostar is the pre - main - sequence stage where the star is still contracting and heating up but has not yet started nuclear fusion. A planetary nebula is the remnant of a low - mass star at the end of its life, and a supernova is a violent explosion at the end of a high - mass star's life.

Answer:

C. Main sequence