Cooling-controlled planetary envelope growth
= Cooling-controlled planetary envelope growth
Gravitational binding is necessary but not sufficient for <gas> capture. A hydrostatic envelope contracts by losing energy on a Kelvin-Helmholtz scale $t_{\rm KH}\sim|E|/L$. Solid accretion heats it, while radiative transport depends on <opacity> and <convection> carries energy when the radiative gradient is unstable. The disk supply and outer tidal/thermal boundaries also matter.