Accurate p-mode measurements of the G0V metal-rich CoRoT^⋆ target HD 52265

¹ Institut de Recherche en Astrophysique et Planétologie, CNRS, 14 avenue Edouard Belin, 31400 Toulouse, France
e-mail: jballot@ast.obs-mip.fr
² Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
³ Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany
⁴ LESIA, UMR 8109, Université Pierre et Marie Curie, Université Denis Diderot, Observatoire de Paris, 92195 Meudon, France
⁵ Institut d’Astrophysique Spatiale, CNRS, Université Paris XI, 91405 Orsay, France
⁶ Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia
⁷ Astronomy Unit, Queen Mary, University of London Mile End Road, London E1 4NS, UK
⁸ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
⁹ Danish AsteroSeismology Centre, Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark
¹⁰ Centro de Astrofísica, DFA-Faculdade de Ciências, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹¹ Laboratoire AIM, CEA/DSM, CNRS, Université Paris Diderot, IRFU/SAp, Centre de Saclay, 91191 Gif-sur-Yvette Cedex, France
¹² High Altitude Observatory, NCAR, PO Box 3000, Boulder, CO 80307, USA
¹³ Universidad de La Laguna, Dpto de Astrofísica, 38206 La Laguna, Tenerife, Spain
¹⁴ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
¹⁵ Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur, BP 4229, 06304 Nice Cedex 4, France

Received: 20 January 2011
Accepted: 22 March 2011

Abstract

Context. The star HD 52265 is a G0V metal-rich exoplanet-host star observed in the seismology field of the CoRoT space telescope from November 2008 to March 2009. The satellite collected 117 days of high-precision photometric data on this star, showing that it presents solar-like oscillations. HD 52265 was also observed in spectroscopy with the Narval spectrograph at the same epoch.

Aims. We characterise HD 52265 using both spectroscopic and seismic data.

Methods. The fundamental stellar parameters of HD 52265 were derived with the semi-automatic software VWA, and the projected rotational velocity was estimated by fitting synthetic profiles to isolated lines in the observed spectrum. The parameters of the observed p modes were determined with a maximum-likelihood estimation. We performed a global fit of the oscillation spectrum, over about ten radial orders, for degrees l = 0 to 2. We also derived the properties of the granulation, and analysed a signature of the rotation induced by the photospheric magnetic activity.

Results. Precise determinations of fundamental parameters have been obtained: T_eff = 6100    ±    60   K, log g = 4.35    ±    0.09,  [M/H]  = 0.19    ±    0.05, as well as $\mathit{v}\sin \mathit{i}\mathrm{=}\mathrm{3.}{\mathrm{6}}_{-1.0}^{\mathrm{+}\mathrm{0.3}}\hspace{0.17em}\mathrm{km}\hspace{0.17em}{\mathrm{s}}^{-1}$. We have measured a mean rotation period P_rot = 12.3    ±    0.15 days, and find a signature of differential rotation. The frequencies of 31 modes are reported in the range 1500–2550    μHz. The large separation exhibits a clear modulation around the mean value $\overline{\mathrm{\Delta }\mathit{\nu }}\mathrm{=}\mathrm{98.3}\hspace{0.17em}\mathrm{\pm }\hspace{0.17em}\mathrm{0.1} \hspace{0.17em}\mathit{\mu }\mathrm{Hz}$. Mode widths vary with frequency along an S-shape with a clear local maximum around 1800    μHz. We deduce lifetimes ranging between 0.5 and 3 days for these modes. Finally, we find a maximal bolometric amplitude of about 3.96    ±    0.24 ppm for radial modes.