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Frank Grundahl

A Multi-Site Campaign to Measure Solar-Like Oscillations in Procyon. II. Mode Frequencies

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  • Timothy R. Bedding, University of Sydney, Australia
  • Hans Kjeldsen
  • Tiago L. Campante, Aarhus University, Denmark
  • Thierry Appourchaux, Université Paris XI-CNRS, France
  • Alfio Bonanno, INAF—Osservatorio Astrofisico di Catania, Italy
  • William J. Chaplin, University of Birmingham, United Kingdom
  • Rafael A. Garcia, DAPNIA/DSM/Service d’Astrophysique, France
  • Milena Martić, University of Versailles St Quentin, France
  • Benoit Mosser, Observatoire de Paris, France
  • R. Paul Butler, Carnegie Institution of Washington, United States
  • Hans Bruntt, University of Sydney, Australia
  • László L. Kiss, University of Sydney, Australia
  • Simon J. O’Toole, Anglo-Australian Observatory, Australia
  • Eiji Kambe, National Astronomical Observatory of Japan, Japan
  • Hiroyasu Ando, National Astronomical Observatory of Japan, Japan
  • Hideyuki Izumiura, National Astronomical Observatory of Japan, Japan
  • Bun'ei Sato, Tokyo Institute of Technology, Japan
  • Michael Hartmann, Thüringer Landessternwarte Tautenburg, Germany
  • Artie Hatzes, Thüringer Landessternwarte Tautenburg, Germany
  • Caroline Barban, Laboratoire AIM, CEA/DSM—CNRS–Université Paris Diderot, France
  • Gabrielle Berthomieu, Observatoire de la Côte d’Azur, France
  • Eric Michel, Laboratoire AIM, CEA/DSM—CNRS–Université Paris Diderot, France
  • Janine Provost, Observatoire de la Côte d’Azur, France
  • Sylvaine Turck-Chièze, DAPNIA/DSM/Service d’Astrophysique, France
  • Jean-Claude Lebrun, LATMOS, University of Versailles St Quentin, France
  • Jerome Schmitt, Observatoire de Haute Provence, France
  • Jean-Loup Bertaux, LATMOS, University of Versailles St Quentin, France
  • Serena Benatti, CISAS—University of Padova, Italy
  • Riccardo U. Claudi, INAF—Astronomical Observatory of Padua, Italy
  • Rosario Cosentino, INAF—Osservatorio Astrofisico di Catania, Italy
  • Silvio Leccia, INAF—Osservatorio Astronomico di Capodimonte, Italy
  • Søren Frandsen
  • Karsten Brogaard
  • Lars Glowienka, Denmark
  • Frank Grundahl
  • Eric Stempels, Department of Physics and Astronomy, Sweden
  • Torben Arentoft, Denmark
  • Michael Bazot, Denmark
  • Jørgen Christensen-Dalsgaard
  • Thomas H. Dall, European Southern Observatory, Germany
  • Christoffer Karoff
  • Jens Lundgreen-Nielsen, Aarhus University, Denmark
  • et al., Denmark
  • Department of Physics and Astronomy
  We have analyzed data from a multi-site campaign to observe oscillations in the F5 star Procyon. The data consist of high-precision velocities that we obtained over more than three weeks with 11 telescopes. A new method for adjusting the data weights allows us to suppress the sidelobes in the power spectrum. Stacking the power spectrum in a so-called echelle diagram reveals two clear ridges, which we identify with even and odd values of the angular degree (l = 0 and 2, and l = 1 and 3, respectively). We interpret a strong, narrow peak at 446 mu Hz that lies close to the l = 1 ridge as a mode with mixed character. We show that the frequencies of the ridge centroids and their separations are useful diagnostics for asteroseismology. In particular, variations in the large separation appear to indicate a glitch in the sound-speed profile at an acoustic depth of similar to 1000 s. We list frequencies for 55 modes extracted from the data spanning 20 radial orders, a range comparable to the best solar data, which will provide valuable constraints for theoretical models. A preliminary comparison with published models shows that the offset between observed and calculated frequencies for the radial modes is very different for Procyon than for the Sun and other cool stars. We find the mean lifetime of the modes in Procyon to be 1.29(-0.49)(+0.55) days, which is significantly shorter than the 2-4 days seen in the Sun.
Original languageEnglish
JournalAstrophysical Journal
Pages (from-to)935–949
Publication statusPublished - 29 Mar 2010

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