Life cycle of stars Flashcards
Outline the life cycle of stars
Stellar nebula–> protostar–> main sequence–> giant/supergiant–>super nova/white dwarf–> neutron star/ black hole
What is a stellar nebula?
Interstellar cloud of gases and dust where stars are born
What is a main sequence star?
A celestial object where hydrogen fuses at the core to produce helium and stellar equilibrium is achieved
What is stellar equilibrium?
Outward pressure produced in a star through nuclear fusion is equal to the inward gravitational force
How long does a star spend as a main sequence star?
90% of its lifespan
Why do high mass main sequence stars have a shorter lifespan?
Higher mass stars have a higher gravitational force, thus it must produce more pressure through nuclear fusion to maintain stellar equilibrium. Thus, more fusion reactions are needed so fuel is burned at a faster rate and is depleted faster. Thus, higher mass stars have a shorter lifespan.
What are the characteristics of a high mass main sequence star?
- H–>He at core
- fast, doesn’t last long
- high lumin
- high temp
What are the characteristics of a low mass main sequence star?
- H–> He at core
slow, lasts a long time - low temp
- low lumin
What are the characteristics of a red supergiant?
- He–> C fusion
C–> O, etc until Fe - low temp
- high lumin
- lots of released energy
- star swells
What are the characteristics of a red giant?
- fuses He–> C
- lots of energy released
- star expands
- low temp
- high lumin
What are the characteristics of a supernova?
Explosion, heavy elements (gold, uranium)
What is a planetary nebula also known as?
White dwarf
What can a supernova turn into?
Neutron star or black hole
