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Oscillation mode linewidths of main-sequence and subgiant stars observed by Kepler

T. Appourchaux, O. Benomar, M. Gruberbauer, W. J. Chaplin, R. A. García, R. Handberg, G. A. Verner, H. M. Antia, T. L. Campante, G. R. Davies, S. Deheuvels, S. Hekker, R. Howe, D. Salabert, T. R. Bedding, T. R. White, G. Houdek, V. Silva Aguirre, Y. Elsworth, J. Van Cleve, B. D. Clarke, J. R. Hall, H. Kjeldsen

Abstract
Context. Solar-like oscillations have been observed by Kepler and CoRoT in several solar-type stars.
Aims. We study the variations of stellar p-mode linewidth as a function of effective temperature.
Methods. Time series of 9 months of Kepler data have been used. The power spectra of 42 cool main-sequence stars and subgiants have been analysed using both Maximum Likelihood Estimators and Bayesian estimators, providing individual mode characteristics such as frequencies, linewidths and mode heights.
Results. Here we report on the mode linewidth at maximum power and at maximum mode height for these 42 stars as a function of effective temperature.
Conclusions. We show that the mode linewidth at either maximum mode height or maximum amplitude follows a scaling relation with effective temperature, which is a combination of a power law plus a lower bound. The typical power law index is about 13 for the linewidth derived from the maximum mode height, and about 16 for the linewidth derived from the maximum amplitude while the lower bound is about 0.3 µHz and 0.7 µHz, respectively. We stress that this scaling relation is only valid for the cool main-sequence stars and subgiants, and does not have predictive power outside the temperature range of these stars.

Keywords
methods: data analysis – asteroseismology – stars: solar-type

Astronomy and Astrophysics
Volume 537, Number of pages A134_1
2012 January

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia