rodluger
commented
4 years ago From Trevor David:
Sec. 2.2 of this paper has discussion of spot temperature as a function of Teff https://ui.adsabs.harvard.edu/abs/2015MNRAS.448.3053A/abstract
I just found this review paper, which is highly cited, and talks about spot contrast in Sec. 5. https://link.springer.com/article/10.12942/lrsp-2005-8
The data might come from a combination of Doppler imaging and molecular bandhead modeling. The idea here is just that when the more heavily spotted hemisphere is in view you see a strengthening of bandhead features that are associated with the cool spots - this is shown really nicely in Fig. 11 of Gully's paper https://iopscience.iop.org/article/10.3847/1538-4357/836/2/200/pdf
Differential rotation as a function of Teff/mass https://ui.adsabs.harvard.edu/abs/2005MNRAS.357L...1B/abstract https://ui.adsabs.harvard.edu/abs/2007AN....328.1030C/abstract https://ui.adsabs.harvard.edu/abs/2012A%26A...542A.116A/abstract https://ui.adsabs.harvard.edu/abs/2015A%26A...583A..65R/abstract
Another starspot review paper https://ui.adsabs.harvard.edu/abs/2009A%26ARv..17..251S/abstract
Discussion of polar spots for rapid rotators / low-mass stars https://ui.adsabs.harvard.edu/abs/1992A%26A...264L..13S/abstract https://ui.adsabs.harvard.edu/abs/2015A%26A...573A..68Y/abstract
@RuthAngus suggested looking at KIC 4918333: an M dwarf with a nice looking light curve and probably a couple of active regions. It's used as an example in McQuillan et al. (2013) .