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.