Astronomy and Astrophysics, volume 343, 222-228 (1999/3-1)
The Wilson-Bappu effect of the MgIIk line - dependence on stellar temperature, activity and metallicity.
ELGAROY O., ENGVOLD O. and LUND N.
Abstract (from CDS):
The Wilson-Bappu effect is investigated using accurate absolute magnitudes of 65 stars obtained through early release of data from the Hipparcos satellite together with MgII k line widths determined from high resolution spectra observed with the International Ultraviolet Explorer (IUE) observatory. Stars of spectral classes F, G, K and M and luminosity classes I-V are represented in the sample. Wilson-Bappu relations for the MgIIk line for stars of different temperatures i.e. spectral classes are determined. The relation varies with spectral class and there is a significant scatter of the line widths around the regression lines. The sample contains slowly rotating stars of different activity levels and is suitable for investigations of a possible relation between line width and stellar activity. A difference in behavior between dwarfs and giants (and supergiants) of spectral class K seems to be present. Magnetic activity affects the width of the MgIIk line in dwarfs. Metallicity is found to influence the MgIIk line width in giants and supergiants. Possible interpretations of the new results are briefly discussed.