CoRoT’s view on variable B8/9 stars: spots versus pulsations
Instituut voor Sterrenkunde, K.U. Leuven, Celestijnenlaan
2 LESIA, Observatoire de Paris, CNRS UMR 8109, Université Pierre et Marie Curie, Université Denis Diderot, 5 place J. Janssen, 92105 Meudon, France
3 Department of Astrophysics, IMAPP, University of Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
4 Jeremiah Horrocks Institute of Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK
5 Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 août 17, 4000 Liège, Belgium
6 School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
7 Institut d’Astrophysique Spatiale, CNRS/Université Paris XI, UMR 8617, 91405 Orsay, France
Received: 1 March 2011
Accepted: 3 October 2011
Context. There exist few variability studies of stars in the region in the Hertzsprung-Russell diagram between the A and B-star pulsational instability strips. With the aid of the high precision continuous measurements of the CoRoT space satellite, low amplitudes are more easily detected, making a study of this neglected region worthwhile.
Aims. We collected a small sample of B stars observed by CoRoT to determine the origin of the different types of variability observed.
Methods. We combine literature photometry and spectroscopy to measure the fundamental parameters of the stars in the sample, and compare asteroseismic modelling of the light curves with (differentially rotating) spotted star models.
Results. We found strong evidence for the existence of spots and differential rotation in HD 174648, and formulated hypotheses for their origin. We show that the distinction between pulsations and rotational modulation is difficult to make solely based on the light curve, especially in slowly rotating stars.
Key words: stars: activity / stars: early-type / stars: atmospheres / asteroseismology / stars: rotation / stars: individual: HD 174648
The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA’s RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.
Based on observations made with the ESO telescopes at La Silla Observatory under the ESO Large Programme LP182.D-0356.
Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2011