The Spectra of Red Variables: SC Stars
The value of recording the spectra of red stars depends upon one’s point of view. On the one side, to those concerned with spectral classification in general, it is of the greatest aid in calibrating the criteria of classification if those criteria are observed in a variable star in which the physical variables change by a known amount. Thus the temperature differences, amounting to three or four hundred degrees, between the maximum and minimum phases of Mira variables, have helped to establish the temperature criteria that are in general use for the coolest stars.On the other hand, I am sure that at this meeting there is more interest in the inverse problem: how to use the behavior of the spectral features to learn more about what is going on in the variable star - or, at least, at their surfaces.