# Bolometric Magnitude Etc.

1. May 31, 2005

### ek

Q: Find an expression for the absolute bolometric magnitude of a star as a function of its effective temperature and radius, which incorporates the solar value of these quantities (BM 4.7, Temp 5780K, radius 6.96E5 km) and not Stefan's constant.

I'm a little lost on this question. I know what Bolometric magnitude is but don't know how to express it explicitly in terms of T and r. maybe I am missing some large concept here, I don't really know. Can someone help me out?

Thanks.

2. May 31, 2005

### SpaceTiger

Staff Emeritus
Several things to try to answer. First, just because your result won't include $$\sigma$$ doesn't mean you shouldn't use the Stephan-Boltzmann law. Do you know what that is?

Second, what is the bolometric magnitude? What is the bolometric luminosity?

Finally, how are magnitude systems usually normalized?