By Sakshi Sah
Published Sep 04, 2024

Hindustan Times

Photo Credits: NASA

8 NASA pics show final moments of a dying star

A star is a massive, glowing ball of gas that produces its own light and energy.

A star's life cycle is determined by its mass. The larger its mass, the shorter its life cycle.

Stars spend most of their lives burning hydrogen in their cores. As they age, this process changes, leading to their eventual death.

Astronomers estimate the universe has up to one septillion stars (1 followed by 24 zeros), with the Milky Way alone housing over 100 billion, including our Sun.

Once a star exhausts its hydrogen fuel, it starts to burn heavier elements like helium, causing it to expand and become a red giant.

All stars start as a cloud of dust and gas, or nebula, which forms a protostar and then becomes a main sequence star. How a star evolves next depends on its size.

A star forms when hydrogen nuclei fuse to create helium, releasing energy that keeps the star’s core hot.

During the stable phase, gravity pulling the star inwards is balanced by the high pressure from its hot temperatures.

When the hydrogen is used up, the star starts forming larger nuclei and may expand into a red giant.

When all the nuclear reactions are over, small stars begin to contract under the pull of gravity and become a white dwarf.

A larger star continues nuclear reactions, growing hotter and expanding until it explodes as a supernova.

Depending on the mass at the start of its life, a supernova leaves behind either a neutron star or a black hole.