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Starspot Activity and Superflares on Solar-type Stars

Published online by Cambridge University Press:  12 September 2017

Hiroyuki Maehara
Hiroyuki Maehara*
Affiliation:
Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, 3037-5 Honjo, Kamogata, Asakuchi, Okayama, Japan, 719-0232 email: h.maehara@oao.nao.ac.jp
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Abstract

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Recent high-precision photometry from space (e.g., Kepler) enables us to investigate the nature of “superflares” on solar-type stars. The bolometric energy of superflares detected by Kepler ranges from 1033 erg to 1036 erg which is 10-10,000 times larger than that released by a typical X10 class solar flare. The occurrence frequency (dN/dE) of superflares as a function of flare energy (E) shows the power-law distribution with the power-law index of ~−1.8 for 1034 < E < 1036 erg. Most of superflare stars show quasi-periodic light variations which suggest the presence of large starspots. The bolometric energy released by flares is consistent with the magnetic energy stored near the starspots. The occurrence frequency of superflares increases as the rotation period decreases. However, the energy of the largest flares observed in a given period bin does not show any clear correlation with the rotation period. These results suggest that superflares would occur on the slowly-rotating stars.

Keywords

stars:activitystars:flarestars:solar-type
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 12 , Symposium S328: Living Around Active Stars , October 2016 , pp. 22 - 29
Copyright
Copyright © International Astronomical Union 2017 

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