| Issue |
A&A
Volume 476, Number 2, December III 2007
|
|
|---|---|---|
| Page(s) | 881 - 891 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361:20041806 | |
| Published online | 23 October 2007 | |
Study of FK Comae Berenices*,**,***
V. Spot evolution and detection of surface differential rotation
1
Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14882 Potsdam, Germany e-mail: hkorhonen@aip.de
2
Institute of Astronomy, ETH-Zentrum, 8092 Zürich, Switzerland
3
Tuorla Observatory, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
4
Observatory, PO Box 14, 00014 University of Helsinki, Finland
Received:
16
May
2006
Accepted:
18
September
2007
Aims.We investigate the spot evolution and the surface differential rotation of the single late-type giant FK Com.
Methods.A total of 18 new surface temperature maps of FK Com are calculated with the Doppler imaging technique for the years 1993–2003. Photometric observations from 2002–2004 are also given. The new and previously published spectroscopic and photometric observations are used to study the spot locations and lifetimes, and to estimate the value of the surface differential rotation.
Results.The phases of the active regions determined from the Doppler images
follow closely the active longitudes determined earlier from the long-term
photometric observations. One active longitude can remain active for several
years, but the exact spot configuration within the active longitude changes
on much shorter time scales, indicating that the spot lifetime is months
instead of years. There are periods during which the spot configuration
changes even within days. Measurements using spot latitudes from the Doppler
images and spot rotation periods from the photometric observations yield a
surface differential rotation law of 
and the relative differential rotation coefficient
for FK Comae.
Key words: stars: activity / stars: late-type / stars: starspots / stars: individual: FK Comae Berenices
Based on observations obtained at the Nordic Optical Telescope, Observatorio Roque de los Muchachos, La Palma, Canary Islands, Spain; the Kitt Peak National Observatory, USA; the National Astronomical Observatory, Rozhen, Bulgaria; Automatic Photometric Telescopes Phoenix 10, Wolfgang and Amadeus, Arizona, USA.
© ESO, 2007
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.