Variable Stars in M13
From the author of Welcome to the Universe in 3D
Click on image for full uncropped version
Variable stars are shown as pairs of points connected by a line-segment
Stars above the red line are presumed to be variable stars.
Variable stars between magnitude 13 and 14 are the RR-Lyrae stars.
Here are the two image files (in "fits" format):
m13_2009-LRGB.fit
m13_2014-LRGB.fit
Here is the Matlab function used to make the HR-diagram:
makeHRdiagRRlyrae.m
Click here for webpage showing individual images of M13