Stars do not last forever. They have finite lives and so they are born and they die. How are stars formed? First, we must start with the correct
ingredients. Huge volumes of space with the correct collection of atoms and molecules at the correct density are called molecular clouds. One of the
most famous molecular clouds is the nearby Orion Nebula. Let’s take a tour of this famous nebula. The life of a star is determined from the very
beginning by the amount of mass used to make the star. From Hubble Space Telescope images, we know that star formation is going on right now
in the Orion Nebula. We see what have been called proplyds. The lowest possible mass for a star seems to be about 0.08 solar masses. Any mass
smaller than that becomes what is called a brown dwarf. Whereas the most massive stars might have as much as 150 times the mass of the Sun.
The details of star formation are illustrated in Hayashi tracks.
Step 1 - Molecular Cloud
Step 2 - Collapsing Cloud Fragment
Step 3 - Fragmentation Ceases
Step 4 - Protostar
Here are seven steps to star formation
Looking for a particular star? Find it here!
