What is the condition for balancing p_{electron } and p_{grav} ?
We set
p_{electron }= p_{grav} , (36.9)
and using eqns 36.5 and 36.8 this implies that
p_{electron} =\frac{2}{3} u =\frac{\hbar ^{2} }{5m_{e} } (3π^{2} )^{2/3} n^{5/3} . (36.5)
p_{grav} = \frac{Ω}{3V} =-\frac{G }{5}\left(\frac{4π }{3} \right) ^{1/3} M^{2/3} ρ^{4/3} , (36.8)
ρ =\frac{4G^{3} M^{2} m^{3}_{e} }{27π^{3} \hbar^{6} } \left(\frac{Am_{p} }{Z} \right) ^{5}. (36.10)