# Calculate the equilibrium temperature!
#
# This function calculates the equilibrium temperature
# of a planet at a given distance away from from a star
# of a certain size, applying the definition:
#
# Tp^4 = Tstar^4 * (1 - A) * (Rstar / 2a)^2
#
# inputs:
# tstar = stellar temp in kelvin
# rstar = stellar radii in solar radii
# dplanet = planet semi-major axis in AU
# keywords:
# alb = bond albedo
# = 0 if not set
#
# Build and Reload Package: 'Cmd + Shift + B'
# Check Package: 'Cmd + Shift + E'
# Test Package: 'Cmd + Shift + T'
calc_teq <- function(tstar,rstar,dplanet,alb=NA){
rsolar <- 6.957e10 # solar radius in cm
au <- 1.496e13 # AU in cm
# convert rstar, dplanet to cm
rstar_cm <- rstar * rsolar # rsolar --> cm
dplanet_cm <- dplanet * au # AU --> cm
# if no albedo is supplied, then just set = 0.0
if (is.na(alb)) {
alb <- 0.0
}
# calculate teq^4
teq_planet4th <- (tstar)^4.0 * (1.0 - alb) * (rstar_cm / (2.0 * dplanet_cm))^2.0
# calculate teq
teq_planet <- teq_planet4th^0.25
# return the planet equilibrium temp
return(teq_planet)
}
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