Bow shock around the very young star LL Ori.
Stars form in dense molecular clouds within galaxies. These clouds of dust and gas obscure the early stages of stellar formation from optical telescopes. Fortunately recent advances in radio and infrared astronomy now allow astronomers to peer inside these clouds and gain a greater understanding of the processes involved in starbirth. Computationally intensive computer simulations also allow them to model the processes and test the results against observations.
Gravity is the force responsible for stellar formation and the mass of material that forms at star largely determines its life and fate.
Stars live for a very long time compared to human lifetimes. Even though stellar life-spans are enormous,
we know how stars are born, live, and die. All stars follow the same basic series of steps in their lives:
Gas Cloud ‡ Proto star ‡ Main Sequence star ‡ Red Giant and/or Supergiant ‡ Horizontal Branch
star (only if it has a low mass) ‡ Variable Star (RR Lyra, Cepheid or WVirgins) ‡ Red Giant and/or
Supergiant ‡ Planetary Nebula (low mass) or Supernova (high mass star) ‡ Stellar Remnant (white
Dwarf, Neutron Star, or Black Hole).