Fundamental properties of five Kepler stars using global asteroseismic quantities and ground-based observations

¹ IAC Instituto de Astrofísica de Canarias, C/ vía Láctea s/n, 38200 Tenerife, Spain ,
e-mail: ocreevey@oca.eu
² Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez s/n, 38206 La Laguna, Tenerife, Spain
³ Université de Nice, Laboratoire Cassiopée, CNRS UMR 6202, Observatoire de la Côte d’Azur, BP 4229, 06304 Nice Cedex 4, France
⁴ Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
⁵ High Altitude Observatory, NCAR, PO Box 3000, Boulder, CO 80307, USA
⁶ INAF, Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95123 Catania, Italy
⁷ Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Santa Cruz de Tenerife, Spain
⁸ Department of Astronomy, Yale University, PO Box 208101, New Haven, CT 06520-8101, USA
⁹ Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208016, India
¹⁰ INAF, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
¹¹ Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
¹² Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal
¹³ Homi Bhabha Centre for Science Education (TIFR), V. N. Purav Marg, Mankhurd, Mumbai 400088, India
¹⁴ Instytut Astronomiczny, Uniwersytet Wrocławski, ul. Kopernika 11, 51-622, Wrocław, Poland
¹⁵ Indian Institute of Science Education and Research Pune, Sai Trinity Building, Garware Circle, Pashan, Pune 411021, India
¹⁶ Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Australia
¹⁷ Indian Institute of Technology Madras, Chennai - 600036, India
¹⁸ Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/SAp, Centre de Saclay, 91191 Gif-sur-Yvette, France
¹⁹ Canadian Space Agency, 6767 route de l’Aéroport, Saint-Hubert, QC, J3Y 8Y9, Canada
²⁰ School of Physics and Astronomy, University of Birmingham, Edgbaston, B15 2 TT Birmingham, UK
²¹ SETI Institute/NASA Ames Research Center, Moffett Field, CA 94035, USA
²² Bay Area Environmental Research Inst./NASA Ames Reseach Center, Moffett Field, CA 94035, USA
²³ Department of Physics, Dezhou University, 253023 Dezhou, PR China
²⁴ Instituto de Astrofísica de Andalucía (CSIC). Glorieta de la Astronomía S/N. CP 3004 Granada, Spain

Received: 4 April 2011
Accepted: 10 November 2011

Abstract

We present an asteroseismic study of the solar-like stars KIC 11395018, KIC 10273246, KIC 10920273, KIC 10339342, and KIC 11234888 using short-cadence time series of more than eight months from the Kepler satellite. For four of these stars, we derive atmospheric parameters from spectra acquired with the Nordic Optical Telescope. The global seismic quantities (average largefrequency separation and frequency of maximum power), combined with the atmospheric parameters, yield the mean density and surface gravity with precisions of 2% and  ~0.03 dex, respectively. We also determine the radius, mass, and age with precisions of 2–5%, 7–11%, and  ~35%, respectively, using grid-based analyses. Coupling the stellar parameters with photometric data yields an asteroseismic distance with a precision better than 10%. A vsini measurement provides a rotational period-inclination correlation, and using the rotational periods from the recent literature, we constrain the stellar inclination for three of the stars. An Li abundance analysis yields an independent estimate of the age, but this is inconsistent with the asteroseismically determined age for one of the stars. We assess the performance of five grid-based analysis methods and find them all to provide consistent values of the surface gravity to  ~0.03 dex when both atmospheric and seismic constraints are at hand. The different grid-based analyses all yield fitted values of radius and mass to within 2.4σ, and taking the mean of these results reduces it to 1.5σ. The absence of a metallicity constraint when the average large frequency separation is measured with a precision of 1% biases the fitted radius and mass for the stars with non-solar metallicity (metal-rich KIC 11395018 and metal-poor KIC 10273246), while including a metallicity constraint reduces the uncertainties in both of these parameters by almost a factor of two. We found that including the average small frequency separation improves the determination of the age only for KIC 11395018 and KIC 11234888, and for the latter this improvement was due to the lack of strong atmospheric constraints.