STELLAR AGES AND CONVECTIVE CORES IN FIELD MAIN-SEQUENCE STARS: FIRST ASTEROSEISMIC APPLICATION TO TWO KEPLER TARGETS

Journal Article · Sat Jun 01 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/769/2/141· OSTI ID:22127193

Silva Aguirre, V.; Christensen-Dalsgaard, J.; Chaplin, W. J. ^[1]; Basu, S.; Deheuvels, S. ^[2]; Brandao, I. M.; Cunha, M. S.; Sousa, S. G. ^[3]; Dogan, G. ^[4]; Metcalfe, T. S. ^[5]; Serenelli, A. M.; Garcia, R. A. ^[6]; Ballot, J. ^[7]; Weiss, A. ^[8]; Appourchaux, T. ^[9]; Casagrande, L. ^[10]; Cassisi, S. ^[11]; Creevey, O. L. ^[12]; Lebreton, Y. ^[13]; Noels, A. ^[14] ; others, and

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1. Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)
2. Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)
3. Centro de Astrofisica and Faculdade de Ciencias, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)
4. High Altitude Observatory, NCAR, P.O. Box 3000, Boulder, CO 80307 (United States)
5. Space Science Institute, Boulder, CO 80301 (United States)
6. Kavli Institute for Theoretical Physics, Santa Barbara, CA 93106 (United States)
7. Institut de Recherche en Astrophysique et Planetologie, CNRS, 14 avenue Edouard Belin, F-31400 Toulouse (France)
8. Max Planck Institute for Astrophysics, Karl-Schwarzschild-Str. 1, D-85748 Garching bei Muenchen (Germany)
9. Institut d'Astrophysique Spatiale, Universite Paris Sud-CNRS (UMR8617) Batiment 121, F-91405 Orsay Cedex (France)
10. Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, The Australian National University, ACT 2611 (Australia)
11. INAF-Astronomical Observatory of Teramo, Via M. Maggini sn, I-64100 Teramo (Italy)
12. Laboratoire Lagrange, Universite de Nice Sophia-Antipolis, CNRS, I-06300 Nice, France. (France)
13. Observatoire de Paris, GEPI, CNRS UMR 8111, F-92195 Meudon (France)
14. Institute of Astrophysics and Geophysics, University of Liege, B-4000 Liege (Belgium)

Using asteroseismic data and stellar evolution models we obtain the first detection of a convective core in a Kepler field main-sequence star, putting a stringent constraint on the total size of the mixed zone and showing that extra mixing beyond the formal convective boundary exists. In a slightly less massive target the presence of a convective core cannot be conclusively discarded, and thus its remaining main-sequence lifetime is uncertain. Our results reveal that best-fit models found solely by matching individual frequencies of oscillations corrected for surface effects do not always properly reproduce frequency combinations. Moreover, slightly different criteria to define what the best-fit model is can lead to solutions with similar global properties but very different interior structures. We argue that the use of frequency ratios is a more reliable way to obtain accurate stellar parameters, and show that our analysis in field main-sequence stars can yield an overall precision of 1.5%, 4%, and 10% in radius, mass, and age, respectively. We compare our results with those obtained from global oscillation properties, and discuss the possible sources of uncertainties in asteroseismic stellar modeling where further studies are still needed.

• OSTI ID: 22127193
• Journal Information: Astrophysical Journal, Vol. 769, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCURACY
DETECTION
LIFETIME
LIMITING VALUES
MAIN SEQUENCE STARS
MASS
MATHEMATICAL SOLUTIONS
MIXING
OSCILLATIONS
SIMULATION
STAR EVOLUTION
SURFACES