If we assume that the solar nebula (the prot oplanetary disk that formed our solar system) is optically thin and only heated via solar radiation, then can make some as sumptions to calculate the temperature of the solar nebula as a function of distance from the sun. in order for the nebula to be in thermal equilibrium, the power ab- sorbed, based on distance from the sun and solar luminosity) must be equal to the power the nebula radiates outward, which is in turn related to the temperature of the solar nebula at that point. this derivation can be applied to other planetary systems using the fact that luminosity scales with m4. this gives us m. /2) ( tequi = 208 k( 1 au mo the frost line is then the distance at which water begins to freeze. calculate this distance for each of the stars below o-type star with a mass of m. =20m b. an a-type star with a mass of m. 2m k-type star with a mass of m, 0.8m d. an m-type star with a mass of m, 0.08mo e. what do these results mean for exoplanet demographics? what do these results tell us about planet formation?