On the determination of stellar rotation and differential rotation from chromospheric activity data

Abstract

Methods of determining stellar rotation and differential rotation from data sets of chromospheric activity indicators are discussed from the point of view of establishing required properties of the time series. Problems inherent in determining differential rotation and partial solutions to these difficulties are addressed. Detection and characterization of stellar differential rotation is a difficult, but approachable goal, and requires a better signal-to-noise ratio in the observations than the problem of rotation period determination. A solar data set of plage areas from the summer of 1982 is used to illustrate the technique.