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Short-term spectral variability in AB Aurigae: Clues for activity in Herbig AE stars. II - The CA II K line

DOI

31

Citations

0

References

1986

Year

C. Catala, P. Felenbok, J. Czarny, A. Talavera, Ann Merchant Boesgaard
The Astrophysical Journal

Abstract

The Herbig Ae star AB Aur (A0ep) was monitored with the CFH 3.6 m and the Observatoire de Haute-Provence 1.52 m telescopes in the Ca II K line, for six nights in 1982 October. Some of the 39 recorded spectra were simultaneous with ultraviolet spectra obtained with IUE. The Ca II K line is variable and modulated with a period of 32±4 hours, corresponding to the estimated rotation period of the star. The difference between the 45 hour period found in the Mg II data (Paper I) and the 32 hour period in the Ca II data is assumed as due to a differential rotation in the envelope of the star. This differential rotation allows an estimate of upper limits for the magnetic field and the Alfvén radius in the envelope of AB Aur, as well as for the rate of angular-momentum loss.