Star Life Cycles (35)

1. Star Life Cycles (35)

2. Pre-birth Stars Stars are born in nebula. Expanses of dust and gas (hydrogen atoms). Protostars begin to form when gravity pulls the matter together.

3. Pre-birth Stars (cont.) Not all protostars become stars. If a protostar is too small (up to 80 times the size of Jupiter) it can’t start fusion. Becomes a brown dwarf.

4. Star Birth Fusion begins: H He. Becomes a main sequence star. Maintains hydrostatic equilibrium. Gravity vs. Pressure (from fusion). Massive stars die faster than smaller. Burn through fuel faster.

5. Star Death How a star dies depends on its mass.

6. Low Mass Stars Up to 1.5 times mass of sun. H all used up. Heats up until He can fuse into Carbon. Star expands & is a Red Giant. (large, cool). He used up and outer layers form a planetary nebula. Leftover core is a White dwarf (hot, small star). White dwarf cools  Black dwarf.

8. Medium Mass Stars 1.5 to 3 times the mass of the sun. H all used up and fuses He. Becomes Red supergiant (VERY large, cool) Runs out of fuels, core collapses to cause Supernova. Core forms a Neutron star (made of only of neutrons).

10. Massive Stars 3+ times the mass of the sun. Same as medium mass stars, except instead of the core forming a neutron star it forms a Black hole.