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Observations of Intensity Fluctuations Attributed to Granulation and Faculae on Sun-like Stars from the Kepler Mission

C. Karoff, T. L. Campante, J. Ballot, T. Kallinger, M. Gruberbauer, R. A. García, D. A. Caldwell, J. L. Christiansen, K. Kinemuchi

Abstract
Sun-like stars show intensity fluctuations on a number of timescales due to various physical phenomena on their surfaces. These phenomena can convincingly be studied in the frequency spectra of these stars—while the strongest signatures usually originate from spots, granulation, and p-mode oscillations, it has also been suggested that the frequency spectrum of the Sun contains a signature of faculae. We have analyzed three stars observed for 13 months in short cadence (58.84 s sampling) by the Kepler mission. The frequency spectra of all three stars, as for the Sun, contain signatures that we can attribute to granulation, faculae, and p-mode oscillations. The temporal variability of the signatures attributed to granulation, faculae, and p-mode oscillations was analyzed and the analysis indicates a periodic variability in the granulation and faculae signatures—comparable to what is seen in the Sun.

Keywords
stars: activity - stars: individual: KIC 6603624 KIC 6933899 KIC 11244118 - stars: oscillations - stars: solar-type

The Astrophysical Journal
Volume 767, Number 1, Page 34_1
2013 April

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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