25
Isothermal Gas Spheres
•
Fit the function to an observed distribution.
–
N(q) = ½ at q=3, or
core radius
R
1/2
=3
α
.
•
To get a central mass density then also need
to measure the velocity distribution.
From
equipartition ½ m<v
2
>=3/2 kT.
So: