I posted it under celestia development forums but I wonder if, per chance, it is my misconception, so I ask it here. Is that true that absolute magnitude should be proportional to star temperature; that is, are hotter stars always brighter? edit: okay, I looked things up, changed my plot a bit, so now it looks more like right. http://img167.imageshack.us/img167/565/aaaaawm9.jpg but. this means stars that are not in "main sequence" cannot be modelled by black bodies. what are their spectrum models?