151. SEISMIC EVIDENCE FOR A RAPIDLY ROTATING CORE IN A LOWER-GIANT-BRANCH STAR OBSERVED WITHKEPLER
- Author
-
Sarbani Basu, T. Stahn, Jessie L. Christiansen, Laurent Gizon, Marc H. Pinsonneault, M. J. Goupil, Luca Casagrande, C. Régulo, Benoit Mosser, S. Deheuvels, Debra A. Fischer, Hans Kjeldsen, Saskia Hekker, Othman Benomar, Daniel R. Reese, Guy R. Davies, Yvonne Elsworth, H. M. Antia, Karen Kinemuchi, Jesper Schou, Savita Mathur, Rafael A. García, Fergal Mullally, Jeff A. Valenti, Jørgen Christensen-Dalsgaard, Thierry Appourchaux, William J. Chaplin, Department of Astronomy, Yale University, 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), Etoile, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Kavli Institute for Theoretical Physics and Department of Physics, University of California, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Tata Institute of Fundamental Research (TIFR), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Sydney Institute for Astronomy (SIfA), School of Physics and Astronomy, University of Birmingham, Institut für Astrophysik, Universität Göttingen, Institut d'Astrophysique, Géophysique et Océanographie, Université de Liège, Instituto de Astrofísica de Canarias (IAC), W.W. Hansen Experimental Physics Laboratory, Stanford University, Mount Stromlo Observatory, Australian National University, Danish AsteroSeismology Centre (DASC), Astronomical Institute Anton Pannekoek, University of Amsterdam, High Altitude Observatory, National Center for Atmospheric Research, Space Telescope Science Institute (STScI), SETI Institute, NASA Ames Research Center, Moffett Field, Bay Area Environmental Research Institute/NASA Ames Research Center, Moffett Field, and Low Energy Astrophysics (API, FNWI)
- Subjects
Physics ,Angular momentum ,010308 nuclear & particles physics ,Red giant ,Stellar rotation ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Rotation ,01 natural sciences ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,0103 physical sciences ,Angular momentum coupling ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,010303 astronomy & astrophysics ,Stellar evolution ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Envelope (waves) - Abstract
Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very complex to take into account in stellar models. To achieve a better understanding of these processes, we desperately need observational constraints on the internal rotation of stars, which until very recently were restricted to the Sun. In this paper, we report the detection of mixed modes - i.e. modes that behave both as g modes in the core and as p modes in the envelope - in the spectrum of the early red giant KIC7341231, which was observed during one year with the Kepler spacecraft. By performing an analysis of the oscillation spectrum of the star, we show that its non-radial modes are clearly split by stellar rotation and we are able to determine precisely the rotational splittings of 18 modes. We then find a stellar model that reproduces very well the observed atmospheric and seismic properties of the star. We use this model to perform inversions of the internal rotation profile of the star, which enables us to show that the core of the star is rotating at least five times faster than the envelope. This will shed new light on the processes of transport of angular momentum in stars. In particular, this result can be used to place constraints on the angular momentum coupling between the core and the envelope of early red giants, which could help us discriminate between the theories that have been proposed over the last decades., Comment: Accepted in ApJ, 39 pages, 16 figures
- Published
- 2012