Lesson Four Topics

Lesson Four Overview
Star Formation
Stellar Nurseries
Star Life
Star Death
Supernovae
Supernova Remnants
Pulsars
Black Holes

	Activities and Quizzes

Lesson Four : Star Formation

In the sweeping gulfs of interstellar space, new stars are born from vast clouds of gas and dust. These clouds, known as nebulae, are usually formed from the remnants of previous stars that have died and contain all the necessary ingredients for new stars to be born. Ingredients like hydrogen, helium and a mixture of heavy elements and molecules such as water, carbon monoxide, and ammonia.

How do we know this material exists inside the clouds? While a star's birth is shrouded in the interstellar medium of our Milky Way galaxy, the clouds surrounding it emit radio waves with wavelengths unique to each constituent.

Radio astronomy allows astronomers to probe important characteristics of the cloud including velocity, rotation, density, temperature, and composition. Interstellar shocks, likely from ancient supernovae, can trigger the collapse of these clouds to form stars. Although the particles composing nebulae are infinitesimal, they collectively possess enough gravity for the cloud to collapse in upon itself over the course of time.

As the cloud collapses, a dense core forms which attracts more material, until a protostar is formed. A protostar is an object that is in the process of accreting mass to eventually form a true star. The protostar is surrounded by a dense shell of gas and dust called a protostellar disk.