[en] Through the observational study of stellar pulsations, the internal structure of stars can be probed and theoretical models can be tested. The main sequence γ Doradus (Dor) and δ Scuti (Sct) stars with masses 1.2-2.5 M[SUB]ȯ[/SUB] are particularly interesting for asteroseismic study. The γ Dor stars pulsate in high-order gravity (g) modes, with pulsational periods of order of one day. The δ Sct stars, on the other hand, show low-order g and pressure (p) modes with periods of order of 2 hours. Theory predicts the existence of `hybrid' stars, i.e. stars pulsating in both types of modes, in an overlap region between the instability strips of γ Dor and δ Sct stars in the Hertzsprung-Russell diagram. Hybrid stars are particularly interesting as the two types of modes probe different regions of the stellar interior and hence provide complementary model constraints. Before the advent of Kepler, only a few hybrid stars had been confirmed. The {{Kepler}} satellite is providing a true revolution in the study of and search for hybrid stars. Analysis of the first 50 days of {{Kepler}} data of hundreds of γ Dor and δ Sct candidates reveals extremely rich frequency spectra, with most stars showing frequencies in both the δ Sct and γ Dor frequency range. As these results show that there are practically no pure δ Sct or γ Dor pulsators, a new observational classification scheme is proposed by \cite{Grig10}. We present their results and characterize 234 stars in terms of δ Sct, γ Dor, δ Sct/γ Dor or γ Dor/δ Sct hybrids.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Grigahcène, A.; Centro de Astrofísica & Dep. Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal
Uytterhoeven, K.; Laboratoire AIM, CEA/DSM CNRS - U. Paris Diderot, IRFU/SAp, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
Antoci, V.; Institut für Astronomie, Türkenschanzstraße 17, A-1080 Wien, Austria
Balona, L.; South African Astronomical Observatory, P.O. Box 9, Observatory 7935, South Africa
Catanzaro, G.; INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
Daszyńska-Daszkiewicz, J.; Instytut Astronomiczny, Uniwersytet Wrocławski, Kopernika 11, 51-622 Wrocław, Poland
Guzik, J. A.; Los Alamos National Laboratory, X-2 MS T-086, Los Alamos, NM 87545-2345, USA
Handler, G.; Institut für Astronomie, Türkenschanzstraße 17, A-1080 Wien, Austria
Houdek, G.; Institut für Astronomie, Türkenschanzstraße 17, A-1080 Wien, Austria
Kurtz, D. W.; Jeremiah Horrocks Institute of Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK
Marconi, M.; INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Naples, Italy
Monteiro, M J P F G; Centro de Astrofísica & Dep. Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Portugal
Moya, A.
Ripepi, V.; INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Naples, Italy
Suárez, J*-C; Instituto de Astrofísica de Andalucía (CSIC), CP3004, Granada, Spain
Borucki, W. J.; NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035, USA
Brown, T. M.; Las Cumbres Observatory Global Telescope, Goleta, CA 93117, USA
Christensen-Dalsgaard, J.; Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
Gilliland, R. L.; Space Telescope Science Institute, Baltimore, MD 21218, USA
Jenkins, J. M.; SETI Institute/NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035, USA
Kjeldsen, H.; Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
Koch, D.; NASA Ames Research Center, MS 244-30, Moffett Field, CA 94035, USA
Bernabei, S.; INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
Bradley, P.; Los Alamos National Laboratory, X-4 MS T-087, Los Alamos, NM 87545-2345, USA
Breger, M.; Institut für Astronomie, Türkenschanzstraße 17, A-1080 Wien, Austria
Di Criscienzo, M.; INAF-Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Rome, Italy
Dupret, Marc-Antoine ; Institut d'Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août 17-B 4000 Liège, Belgium
Garcia, R.
García Hernández, A.; Instituto de Astrofísica de Andalucía (CSIC), CP3004, Granada, Spain
Jackiewicz, J.; Department of Astronomy, New Mexico State University, Las Cruces, NM 88001, USA
Kaiser, A.; Institut für Astronomie, Türkenschanzstraße 17, A-1080 Wien, Austria
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