hertzsprung-russell diagram

(this is an offshoot from this thread: https://forums.frontier.co.uk/index.php?threads/red-giant-or-not-red-giant.510896/ ) I tried doing a plot of Stellar Temperature (x axis) vs Log L on the y axis - calculated from Abs Mag by L = 10^((4.83 - M)/2.5)) - for the 5000 or so stars I've...