3
Chandrasekhar
Limit for White Dwarfs
Add mass to an
existing white dwarf
•Pressure
(P) must increase to balance stronger gravity
•For
degenerate matter, P depends only on density (r), not temperature, so must have higher density
•P
vs. r
rule such that higher mass star must actually have smaller radius to provide enough P
•As
Mstar ® 1.4 MSun velectron ® c
–Requires
much higher r to provide high enough P, so star must be much smaller.
–Strong
gravity which goes with higher r makes this a losing game.
–For
M ³ 1.4 MSun no increase in r can provide enough increase in P – star
collapses
From
our text: Horizons, by Seeds