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Centro de Astrofísica da Universidade do Porto

A Uniform Asteroseismic Analysis of 22 Solar-Type Stars Observed by Kepler

S. Mathur, T. S. Metcalfe, M. Woitaszek, H. Bruntt, G. A. Verner, J. Christensen-Dalsgaard, O. L. Creevey, G. Doǧan, S. Basu, C. Karoff, D. Stello, T. Appourchaux, T. L. Campante, W. J. Chaplin, R. A. García, T. R. Bedding, O. Benomar, A. Bonanno, S. Deheuvels, Y. Elsworth, P. Gaulme, J. A. Guzik, R. Handberg, S. Hekker, W. Herzberg, M. J. P. F. G. Monteiro, L. Piau, P.-O. Quirion, C. Régulo, M. Roth, D. Salabert, A. M. Serenelli, M. J. Thompson, R. Trampedach, T. R. White, J. Ballot, I. M. Brandão, J. Molenda-Żakowicz, H. Kjeldsen, J. D. Twicken, K. Uddin, B. Wohler

Asteroseismology with the Kepler space telescope is providing not only an improved characterization of exoplanets and their host stars, but also a new window on stellar structure and evolution for the large sample of solar-type stars in the field. We perform a uniform analysis of 22 of the brightest asteroseismic targets with the highest signal-to-noise ratio observed for 1 month each during the first year of the mission, and we quantify the precision and relative accuracy of asteroseismic determinations of the stellar radius, mass, and age that are possible using variousmethods. We present the properties of each star in the sample derived from an automated analysis of the individual oscillation frequencies and other observational constraints using the Asteroseismic Modeling Portal (AMP), and we compare them to the results of model-grid-based methods that fit the global oscillation properties. We find that fitting the individual frequencies typically yields asteroseismic radii and masses to ~1% precision, and ages to ~2.5% precision (respectively 2, 5, and 8 times better than fitting the global oscillation properties). The absolute level of agreement between the results from different approaches is also encouraging, with model-grid-based methods yielding slightly smaller estimates of the radius and mass and slightly older values for the stellar age relative to AMP, which computes a large number of dedicated models for each star. The sample of targets for which this type of analysis is possible will grow as longer data sets are obtained during the remainder of the mission.

methods: numerical - stars: evolution - stars: interiors - stars: oscillations

The Astrophysical Journal
Volume 749, Page 152_1
April 2012

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Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

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