nomynameisnotkevin wrote:Smithy0013 wrote:I can't seem to find a mathematical relationship between period and luminosity. Is it necessary just to use graphs and estimate the point on the x and y axis? Or is there an actual equation floating around there somewhere? I derived one myself using a couple known Cepheids but I'd much rather use one from the science community.

I ran into the statement that Period is directly related to luminosity as well, but have no idea if there's a specific equation for everything. Maybe just for certain types. Also, kinda curious what you got for those Cepheids.

Well I only used classical cepheids since its different for every type. But soon after posting this i finally found a relationship (on wikipedia of course I wouldnt look there....). So I compared them for a few and my equation was pretty close so I just deleted it unfortunately. It was the same basic constract with a coefficiant multiplied by a log (I used a natural log as opposed to the base 10 on wikipedia) subtracted by another constant. It really wasnt that impressive since all i did was plug values in excel and make a trend line. Anyway, on wikipedia there is the equation (-2.43)(LOG(P)-1)-4.05 equals your absolute magnitude. Then either use distance modulus or convert to luminosity (another thing I had difficulty finding) and use inverse square law.