Single Chromospherically Active Stars: HD 82443



next up previous
Next: ZAMS K Dwarfs Up: CURRENT RESEARCH Previous: Chromospherically Active Stars:

Single Chromospherically Active Stars: HD 82443

Guinan, Ambruster and s. Messina (Vill. U. & U. Catania) are working with A. F. Lanza (Catania Obs., IT.) on a study of HD 82443 in the Pleiades Moving Group and the results of a long-term photometric monitoring of the young Pleiades moving group member have been submitted to A&. A sequence of eleven optical light curves obtained from 1989 to 1995 confirms the presence of a rotational modulation with a period of 5.40 attributable to cool photospheric spots. The Maximum Entropy and the Tikhonov regularization criteria have been applied to compute maps of the photospheric spot pattern. They show that the total spotted area is subject to changes as large as of the star's surface over time scales of 1-2 years, but without any indication of a cyclical behavior. The overall spot pattern migrates at a variable rate in the sense of the stellar rotation, suggesting the presence of a latitudinal differential rotation with relative amplitude . Nearly simultaneous UV observations obtained in 1991 by Ambruster show the presence of chromospheric and transition region plages which do not seem to be in close spatial association with the photospheric spots. This research was supported under grants from NSF and NASA.



Astronomy
Fri Nov 8 13:37:39 EST 1996