Volume 479, Number 3, March I 2008
|Page(s)||827 - 843|
|Section||Stellar structure and evolution|
|Published online||02 January 2008|
II. The long-term photometric variability of weak-line T Tauri stars
Astronomical Institute of the Uzbek Academy of Sciences, 700052 Tashkent, Uzbekistan
2 Laboratoire d'Astrophysique, Observatoire de Grenoble, Universit Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France
3 Astronomy Department, Wesleyan University, Middletown, CT 06459, USA e-mail: email@example.com
Accepted: 26 December 2007
Context.T Tauri stars exhibit variability on all timescales, whose origin is still debated. On WTTS the variability is fairly simple and attributed to long-lived, ubiquitous cool spots.
Aims.We investigate the long term variability of WTTS, extending up to 20 years in some cases, characterize it statistically and discuss its implications for our understanding of these stars.
Methods.We have obtained a unique, homogeneous database of photometric measurements for WTTS extending up to 20 years. It contains more than 9000 UBVR observations of 48 WTTS. All the data were collected at Mount Maidanak Observatory (Uzbekistan) and they constitute the longest homogeneous record of accurate WTTS photometry ever assembled.
Results.Definitive rotation periods for 35 of the 48 stars are obtained. Phased light curves over 5 to 20 seasons are now available for analysis. Light curve shapes, amplitudes and colour variations are obtained for this sample and various behaviors exhibited, discussed and interpreted.
Conclusions.Our main conclusion is that most WTTS have very stable long term variability with relatively small changes of amplitude or mean light level. The long term variability seen reflects modulation in the cold spot distributions. Photometric periods are stable over many years, and the phase of minimum light can be stable as well for several years. On the long term, spot properties do change in subtle ways, leading to secular variations in the shape and amplitudes of the light curves.
Key words: stars: rotation / stars: fundamental parameters / stars: starspots / stars: variables: general / stars: pre-main sequence
photometric data described in Table [see full text] are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/479/827
© ESO, 2008
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.