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Statistical Study of Solar White-light Flares and Comparison with Superflares on Solar-type Stars

Published online by Cambridge University Press:  27 November 2018

Kosuke Namekata Open the ORCID record for Kosuke Namekata [Opens in a new window] ,
Takahito Sakaue ,
Kyoko Watanabe ,
Ayumi Asai ,
Hiroyuki Maehara ,
Yuta Notsu ,
Shota Notsu Open the ORCID record for Shota Notsu [Opens in a new window] ,
Satoshi Honda ,
Takako T. Ishii  and
Kai Ikuta
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Kosuke Namekata*
Affiliation:
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
Takahito Sakaue
Affiliation:
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
Kyoko Watanabe
Affiliation:
National Defense Academy of Japan, 1-10-20 Hashirimizu, Yokosuka, 239-8686, Japan
Ayumi Asai
Affiliation:
Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471, Japan Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto 607-8471, Japan
Hiroyuki Maehara
Affiliation:
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
Yuta Notsu
Affiliation:
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
Shota Notsu
Affiliation:
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
Satoshi Honda
Affiliation:
Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, Sayo-cho, Sayo-gun, Hyogo, 679-5313, Japan
Takako T. Ishii
Affiliation:
Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471, Japan
Kai Ikuta
Affiliation:
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
Daisaku Nogami
Affiliation:
Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
Kazunari Shibata
Affiliation:
Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471, Japan Unit of Synergetic Studies for Space, Kyoto University, Yamashina, Kyoto 607-8471, Japan
*
*email: namekata@kusastro.kyoto-u.ac.jp
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Abstract

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Recently, many superflares on solar-type stars were discovered as white-light flares (WLFs). A correlation between the energies (E) and durations (t) of superflares is derived as t∝E0.39, and this can be theoretically explained by magnetic reconnection (t∝E1/3). In this study, we carried out a statistical research on 50 solar WLFs with SDO/HMI to examine the t-E relation. As a result, the t-E relation on solar WLFs (t∝E0.38) is quite similar stellar superflares, but the durations of stellar superflares are much shorter than those extrapolated from solar WLFs. We present the following two interpretations; (1) in solar flares, the cooling timescale of WL emission may be longer than the reconnection one, and the decay time can be determined by the cooling timescale; (2) the distribution can be understood by applying a scaling law t∝E1/3B−5/3 derived from the magnetic reconnection theory.

Keywords

solar flaresstellar flaresmagnetic reconnection
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S340: Long-term Datasets for the Understanding of Solar and Stellar Magnetic Cycles , February 2018 , pp. 221 - 224
Copyright
Copyright © International Astronomical Union 2018 

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