6

Chandrasekhar
Limit for White Dwarfs

•**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
M****star**** ****®**** 1.4 M****Sun**** v****electron**** ****®**** 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 M****Sun**** no increase in ****r**** can provide ****enough increase in P – star
collapses
**

From
our text: Horizons, by Seeds