Incompressible planetary interior
= Incompressible planetary interior
{title2=$\rho(r)=\rho_0$}
An idealized self-gravitating interior with constant <mass density>. Negligible surface pressure and spherical <hydrostatic equilibrium> give $M=4\pi\rho R^3/3$ and the <uniform-density planetary pressure profile>. It is the $n=0$ <polytrope> interpretation, rather than a literal substitution into $P=K\rho^{1+1/n}$. It approximates weak compression and misses real compositional stratification.