MOST observations of the roAp stars HD 9289, HD 99563, and HD 134214^⋆

¹ University of Vienna, Institute for Astronomy (IfA), Türkenschanzstrasse 17, 1180 Vienna, Austria
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² Department of Astronomy and Physics, Saint Mary’s University, Halifax, NS B3H 3C3, Canada
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³ Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Australia
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⁴ Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada
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⁵ Départment de physique, Université de Montréal, CP 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7, Canada
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⁶ NASA Ames Research Center, Moffett Field, CA 94035, USA
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⁷ Department of Astronomy & Physics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
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⁸ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
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⁹ Institute of Telecommunications, Vienna University of Technology, Gusshausstrasse 25/389, 1040 Vienna, Austria
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Received: 16 February 2011
Accepted: 11 April 2011

Abstract

We report on the analysis of high-precision space-based photometry of the roAp (rapidly oscillating Ap) stars HD 9289, HD 99563, and HD 134214. All three stars were observed by the MOST satellite for more than 25 days, allowing unprecedented views of their pulsation. We find previously unknown candidate frequencies in all three stars. We establish the rotation period of HD 9289 (8.5 d) for the first time and show that the star is pulsating in two modes that show different mode geometries. We present a detailed analysis of HD 99563’s mode multiplet and find a new candidate frequency that appears to be independent of the previously known mode. Finally, we report on 11 detected pulsation frequencies in HD 134214, nine of which have never before been detected in photometry, and three of which are completely new detections. Thanks to the unprecedentedly small frequency uncertainties, the p-mode spectrum of HD 134214 can be seen to have a well-defined large frequency spacing similar to the well-studied roAp star HD 24712 (HR 1217).