Oct. 25 – 2B03 25/10/2011 9:32:00 AM
Energy Source: Hydrogen Fusion p-p chain
Sun’s energy result of nuclear fusion in its centre.
H into He – pp chain.
o Helium individually less than 4 Hydrogens -> energy off.
o 4.3 milion tonnes per sec -> our sun.
Over time, He builds up in the centre (Helium ash).
Non-burning envelope – vast majority of the star.
As t increases, heavier elements form. Carbon ash forms (carbon core in the
End product of fusion results from mass of star.
Mass (relative stars) increases, results in heavier elements forming.
o Our sun -> carbon.
2) Outer layers fall off (g not too strong).
Planetary nebula – bad name (historically contingent).
Burn H, He ( burning He )makes them large), then start forming C.
White dwarf it the result.
Protostar –> Star (main sequence [H to He] g-type star) -> Red giant ->
Red giant – fucking massive.
Burning He now (temp higher) -> pressure larger -> larger star.
Red giant – brighter, but surface is cooler (red colouration) -> core
is higher though (hot enough to burn He).
White drawf is like the remnant at the end (lot of Carbon).
Cat’s Eye Nebula picture. In a binary system, white dwarf may take some energy from other star ->
may have nuclear burnng again -> special type of supernova (from this
type, dark energy observed)
Most stars are low mass stars (3% high mass)
Evolutionary differences, between low mass and large mass stars.
A teaspoonful of typical white dwarf matter would weigh 5.5 tons on Earth –
as much as an elephant.
Nothing this dense on earth, an