MOST detects corotating bright spots on the mid-O-type giant ξ Persei
- Author(s)
- Tahina Ramiaramanantsoa, Anthony F J Moffat, A. N. Chene, Rainer Kuschnig, Werner Wolfgang Weiss, Noel D. Richardson, Huib F. Henrichs, Sebastien Desforges, Victoria Antoci, Jason F. Rowe, Jaymie M. Matthews, Dimitar Sasselov, Slavek M. Rucinski, David B. Guenther
- Abstract
We have used the MOST (Microvariability and Oscillations of STars) microsatellite to obtain four weeks of contiguous high-precision broad-band visual photometry of the O7.5III(n)((f)) star ξ Persei in 2011 November . This star iswell known from previouswork to showprominent DACs (discrete absorption components) on time-scales of about 2 d from UV spectroscopy and non-radial pulsation with one (l = 3) p-mode oscillation with a period of 3.5 h from optical spectroscopy. Our MOST-orbit (101.4min) binned photometry fails to reveal any periodic light variations above the 0.1 mmag 3s noise level for periods of a few hours, while several prominent Fourier peaks emerge at the 1 mmag level in the two-day period range. These longer period variations are unlikely due to pulsations, including gravity modes. From our simulations based upon a simple spot model, we deduce that we are seeing the photometric modulation of several corotating bright spots on the stellar surface. In our model, the starting times (random) and lifetimes (up to several rotations) vary from one spot to another yet all spots rotate at the same period of 4.18 d, the best-estimated rotation period of the star. This is the first convincing reported case of corotating bright spots on an O star, with important implications for drivers of the DACs (resulting from corotating interaction regions) with possible bright-spot generation via a breakout at the surface of a global magnetic field generated by a subsurface convection zone.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- Universidad de Valparaíso, Universidad de Concepción, University of Amsterdam (UvA), University of Montreal, Aarhus University, NASA Ames Research Center, University of British Columbia (UBC), Harvard-Smithsonian Center for Astrophysics, University of Toronto, Saint Mary's University
- Journal
- Monthly Notices of the Royal Astronomical Society
- Volume
- 441
- Pages
- 910-917
- No. of pages
- 8
- ISSN
- 0035-8711
- DOI
- https://doi.org/10.1093/mnras/stu619
- Publication date
- 06-2014
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy, 103004 Astrophysics
- Keywords
- ASJC Scopus subject areas
- Astronomy and Astrophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/267ef97b-93d6-4b08-b84b-3f1fb9f85f00