# Homework Help: Brightness Temperature of a supernova remnant (calculating)

1. Apr 28, 2009

### TFM

1. The problem statement, all variables and given/known data

A supernova remnant has an angular diameter $$\theta$$ = 4.3 arc minutes and a flux at
100MHz of $$F_{100} = 1.6×10^{-22}J s^{-1}m^{-2}Hz^{-1}$$. Assume that the emission is thermal.
(a) What is the brightness temperature, $$T_b$$?
(b) Suppose that the emitting region were actually more compact than indicated
by the observed angular diameter. What effect would this have on the value of Tb?
(c) What can you say about the temperature of the supernova remnant, based on
the above results?

2. Relevant equations

$$T_{bν} = T_{bν}(0) e^{-T_ν } + T_{kin} (1-e^{-t_ν} )$$

3. The attempt at a solution

I think I have to use the equation I have quoted above, where

$$T_{bν}(0)$$ is $$F_100 = 1.6×10^{-22}J s^{-1}m^{-2}Hz^{-1}$$

But I am not quite sure what the kinetic temperature actually is.