IUE MG II doublet observations in F and G main sequence stars.

Abstract

Mg II resonance lines at 2800 A were studied in the spectra of F and G main sequence stars, observed with the IUE satellite in high resolution mode. Correlation with other chromospheric indicators were investigated and a search was conducted for the best candidates to continue further studies of differential rotation. An attempt has been made to see whether there is a unique relation between the logarithm of the Mg II k emission line width and the absolute visual magnitude, independent of luminosity and emission strengths, as derived for the Ca II K emission line.