A&A 468, 1039-1044 (2007)
Rotational period of GQ LupiC. Broeg1, 2, 3, T. O. B. Schmidt1, E. Guenther2, A. Gaedke4, 1, A. Bedalov1, R. Neuhäuser1, and F. M. Walter5
1 Astrophysikalisches Institut und Universitäts-Sternwarte Jena, Schillergäßchen 2-3, 07745 Jena, Germany
2 Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany
3 Max-Planck Institute for extraterrestrial Physics, Giessenbachstrasse, Garching, 85741, Germany
4 Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
5 Department of Physics and Astronomy, Stony Brook University, NY 11794-3800, USA
(Received 22 November 2006 / Accepted 20 March 2007)
Aims. We wanted to determine the rotation parameters of GQ Lup A, thereby constraining the evolutionary history of the GQ Lup system.
Methods.We have undertaken a photometric monitoring campaign on GQ Lup A consisting of two epochs spaced one year apart. We also searched the photometric archives to enlarge the data set.
Results.We were able to determine the photometric period ( days) in both epochs in several photometric bands. This periodicity could also be found in some of the archival data. The combined false-alarm probability is 0.015. The variation is most likely caused by hot spots on the surface of GQ Lup A. This, combined with high-resolution spectra () allows calculation of GQ Lup A's inclination ( ). Radial velocity data also contains this period but is inconclusive. Nevertheless, the RV data supports the interpretation that hot spots cause the photometric variation. We use the known K-band variability, amplitude, and phase of GQ Lup A together with a new image of GQ Lup A+b, taken quasi-simultaneously with our monitoring of the star, to confirm the magnitude and, hence, luminosity of the companion.
Key words: stars: rotation -- stars: fundamental parameters -- stars: starspots
© ESO 2007