12
Effect
of Degenerate Electron Pressure
•Loss of energy does not reduce
pressure
•Star
does not contract in response to loss of energy
•Gravity
not available as energy source to heat up star
•Electrons
are already in lowest energy states allowed
(equivalent to atoms in ground state) so no energy available there
(equivalent to atoms in ground state) so no energy available there
•If
there is no other energy source, as energy is lost nuclei move slower and temperature drops.
From our text: Horizons, by Seeds
Helium Flash:
Suppose you do initiate He fusion in a degenerate core
non-degenerate, and it finally expands and cools somewhat
to core and eventually heats it to He ignition point
Suppose you do initiate He fusion in a degenerate core
•Extra energy does not immediately raise pressure
•Without extra pressure gas does not expand
•Without expansion gas does not cool
•Extra energy causes gas to heat up
•Higher temperature causes thermonuclear runaway
•Runaway continues till enough energy added to make gas
non-degenerate, and it finally expands and cools somewhat
•Happens in middle mass stars as H shell fusion adds He
ash
to core and eventually heats it to He ignition point