A protostar is a dense cloud of gas and dust that collapses under its own gravity to form a star.

Main sequence stars generate energy through nuclear fusion reactions, where hydrogen atoms are combined to form helium.

As a star exhausts its hydrogen fuel, it expands and becomes a red giant.

Massive stars that undergo a supernova can collapse into a black hole, a region of spacetime with immense gravitational pull.

Low-mass stars end their lives as white dwarfs, dense remnants composed primarily of carbon and oxygen.

A supernova is a powerful explosion that occurs when a massive star reaches the end of its life.

The Hertzsprung-Russell Diagram is a graph that plots the luminosity of stars against their surface temperature.

The mass of a star is primarily determined by the density of the gas cloud from which it forms.

A planetary nebula is a glowing shell of gas and dust ejected by a star as it nears the end of its life.

A black hole is a hypothetical remnant left behind after a star has exhausted all of its nuclear fuel.

The red giant phase is a stage in stellar evolution where a star increases in luminosity and size as it exhausts its hydrogen fuel.

A blue straggler is a type of star that is formed from the merger of two or more stars.

Mass ejection is the process by which a star loses mass through a stellar wind.

A white dwarf is a type of star that is composed primarily of helium and carbon.