|x||Additional mass (kg)|
|d||Density of the additional mass (kg.m-3)|
|M||Original mass of the planet (kg)|
|r||Original planetary radius (m)|
|L||Luminosity of the star, sol: 3.86 x1026 (W)|
|Ro||For a planet: Minimum orbital radius of the planet (m)|
|For a moon: Minimum orbital radius of the planet - Maximum orbital radius of the moon (m)|
Including the exobase height will make the equation too complex, so it is not included at this time.
To solve the equation: use your own value of x until the equation is true.