Journal Article

Analysis of variability of TW Hya as observed by <i>MOST</i> and ASAS in 2009*

Michal Siwak, Slavek M. Rucinski, Jaymie M. Matthews, Grzegorz Pojmański, Rainer Kuschnig, David B. Guenther, Anthony F. J. Moffat, Dimitar Sasselov and Werner W. Weiss

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 410, issue 4, pages 2725-2729
Published in print February 2011 | ISSN: 0035-8711
Published online January 2011 | e-ISSN: 1365-2966 | DOI:
Analysis of variability of TW Hya as observed by MOST and ASAS in 2009*

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As a continuation of our previous studies in 2007 and 2008, new photometric observations of the T Tauri star TW Hya obtained by the MOST satellite and the All Sky Automated Survey (ASAS) project over 40 d in 2009 with temporal resolution of 0.2 d are presented. A wavelet analysis of the combined MOST–ASAS data provides a rich picture of coherent, intermittent, variable-period oscillations, similarly as discovered in the 2008 data. The periods (1.3–10 d) and systematic period shortening on time-scales of weeks can be interpreted within the model of magnetorotationally controlled accretion processes in the inner accretion disc around the star. Within this model and depending on the assumed visibility of plasma parcels causing the oscillations, the observed shortest oscillation period may indicate the stellar rotation period of 1.3 or 2.6 d, synchronized with the disc at 4.5 or 7.1 R, respectively.

Keywords: accretion, accretion discs; stars: individual: TW Hya; stars: rotation

Journal Article.  3470 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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