The link below goes to a wikipedia article on luminosity. It has the formulas you might be asking for. Hope it helps http://en.wikipedia.org/wiki/Luminosity ----- Original Message ----- From: "Gigi Giles" <tahoegiles@sbcglobal.net> To: utah-astronomy@mailman.xmission.com Sent: Friday, November 18, 2011 3:25:38 AM Subject: [Utah-astronomy] magnitude and luminosity Hi Everyone, I'm puzzling over a little mathematical problem so I finally decided to ask for help!  I am trying to calculate the individual masses of a binary system.  I know the apparent magnitudes of the stars (4.03 and 6.00).  I know the distance (5.128 pc).  I know that luminosity is directly related to Mass^3.5.  What I can't seem to do is calculate the luminosity of the components, given the apparent mag.  I have determined that the absolute mags. are 5.48 and 7.45.  I have even found a "luminosity calculator" on the web that gives me the figures (0.55  and 0.09 in solar units), but I really want to know the formula and to check if it is right.  Any help please! thanks, Gigi _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php