51. Observations of the pulsating subdwarf B star Feige 48: Constraints on evolution and companions
- Author
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M. D. Reed, S. D. Kawaler, S. Zola, X. J. Jiang, S. Dreizler, S. L. Schuh, J. L. Deetjen, R. Kalytis, E. Meištas, R. Janulis, D. Ališauskas, J. Krzesiński, M. Vuckovic, P. Moskalik, W. Ogłoza, A. Baran, G. Stachowski, D. W. Kurtz, J. M. González Pérez, A. Mukadam, T. K. Watson, C. Koen, P. A. Bradley, M. S. Cunha, M. Kilic, E. W. Klumpe, R. F. Carlton, G. Handler, D. Kilkenny, R. Riddle, N. Dolez, G. Vauclair, M. Chevreton, M. A. Wood, A. Grauer, G. Bromage, J. E. Solheim, R. Østensen, A. Ulla, M. Burleigh, S. Good, Ö. Hürkal, R. Anderson, E. Pakstiene, Department of Physics, Astronomy, and Materials Science, Missouri State University, Department of Physics and Astronomy, Iowa State University, Astronomical Observatory, Jagiellonia University, National Astronomical Observatoires-CAS, Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Institute of Material Science and Applied Research of Vilnius University, Astronomical Observatory, Institute of Theoretical Physics and Astronomy, Astronomical Observatory, Mount Suhora Observatory, Cracow Pedagogical University, Centrum Astronomiczne im. M. Kopernika, Warszawa (CAMK), Centre for Astrophysics, University of Central Lancashire, Institutt for Fysikk, Universitetet i Tromsø, Department of Astronomy, University of Texas, Southwestern University, Los Alamos National Laboratory (LANL), Centro de Astrofisica da Universidade do Porto (CAUP), Department of Physics and Astronomy, Middle Tennessee State University, South African Astronomical Observatory (SAAO), Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Departement d'Astrophysique Extragalactique et de Cosmologie (DAEC), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Department of Physics and Space Sciences and SARA Observatory, Florida Institute of Technology, Melbourne, Department of Physics and Astronomy, University of Arkansas, Isaac Newton Group of Telescopes, Universidade de Vigo, Department of Physics and Astronomy, University of Leicester, Department of Astronomy and Space Sciences, Ege University, Department of Physics and Astronomy, University of North Carolina, and Ege Üniversitesi
- Subjects
oscillations [stars] ,Subdwarf B star ,stars : individual (Feige 48) ,FOS: Physical sciences ,Astrophysics ,Star (graph theory) ,01 natural sciences ,Stability (probability) ,stars : oscillations ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,individual (Feige 48) [stars] ,Physics ,010308 nuclear & particles physics ,variables: other [stars] ,Astrophysics (astro-ph) ,Mode (statistics) ,Astronomy and Astrophysics ,Horizontal branch ,Subdwarf ,stars : variables : other ,Stars ,Amplitude ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
Since pulsating subdwarf B (sdBV or EC14026) stars were first discovered (Kilkenny et al, 1997), observational efforts have tried to realize their potential for constraining the interior physics of extreme horizontal branch (EHB) stars. Difficulties encountered along the way include uncertain mode identifications and a lack of stable pulsation mode properties. Here we report on Feige 48, an sdBV star for which follow-up observations have been obtained spanning more than four years, which shows some stable pulsation modes. We resolve the temporal spectrum into five stable pulsation periods in the range 340 to 380 seconds with amplitudes less than 1%, and two additional periods that appear in one dataset each. The three largest amplitude periodicities are nearly equally spaced, and we explore the consequences of identifying them as a rotationally split l=1 triplet by consulting with a representative stellar model. The general stability of the pulsation amplitudes and phases allows us to use the pulsation phases to constrain the timescale of evolution for this sdBV star. Additionally, we are able to place interesting limits on any stellar or planetary companion to Feige 48., accepted for publication in MNRAS
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