Australia Telescope National Facility

Temperature as a measure of power

One can treat the power received from an astronomical source as being roughly equivalent to that of a black body.

Formally, a black body is represented by the Planck law, where k is the Boltzmann constant and h is the Planck constant.

However, for low frequencies (and temperatures that are not too low, thus for , the "Rayleigh-Jeans law"), this can be approximated as

This implies that the power received is directly proportional to a temperature. Now, WHICH power are we talking about?