Life Cycle of a Star

By Madelin Fish

Interstellar Medium

Interstellar medium is what fills the spaces in between the stars. It consists of mostly gas and dust. In the milky way, 15% of the matter is interstellar gas and dust.


Pictures & Info: http://www-ssg.sr.unh.edu/ism/what1.html

Nebula Stage

The nebula, where the star is born, has a high density. It then shrinks and becomes a big globule of gas and dust and then pulls in its own gravity.


Info: http://www.astro.keele.ac.uk/workx/starlife/StarpageS_26M.html

Protostar Stage

Matter in this region will begin to shrink and heat up, which will cause it to glow forming protostars. A protostar is the clump that is caused when the interstellar medium comes together but it has not fused yet. If there is enough matter in the protostar, the central temperature will reach 15 million degrees centigrade.


Info: http://www.astro.keele.ac.uk/workx/starlife/StarpageS_26M.html

Main sequence stage

At 15 million degrees, hydrogen fuses to form helium in a nuclear reaction. The star then releases energy which stops it from growing even more and causes it shine.


Info: http://www.astro.keele.ac.uk/workx/starlife/StarpageS_26M.html

Red Giant Stage

In order for the helium to combine with carbon the core has to be hot enough. The outer layers get bigger, cool off, and don't shine as bright. The red giant is the star that is getting bigger.

White Dwarf/Death Stage

The core of what's left of the star becomes a white dwarf which causes the star to cool and dim. When it completely stops shining, it becomes a black dwarf. Anything that doesn't become a black dwarf recycles into a planetary nebula, which then forms a new star.