Survey of active solar-type stars with the wide-filed photometric observations and archival data

• Project/Area Number: 26800096
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Astronomy
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Maehara Hiroyuki 国立天文台, 岡山天体物理観測所, 専門研究職員 (40456851)
• Research Collaborator: Shibata Kazunari 京都大学, 大学院理学研究科, 教授 (70144178) ; Nogami Daisaku 京都大学, 大学院理学研究科, 准教授 (20332728) ; Honda Satoshi 兵庫県立大学, 天文科学センター, 特任助教 (20425408)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000); Fiscal Year 2016: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2015: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000); Fiscal Year 2014: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
• Keywords: 恒星フレア / 光赤外線天文学 / 恒星物理学 / 恒星黒点 / 太陽型星 / 黒点 / スーパーフレア / フレア

Outline of Final Research Achievements

Previous studies by using the data from Kepler suggest that a part of solar-type stars with the rotation period comparable to the Sun (~25 days) show much higher magnetic activity (e.g., superflares). We studied the rotation period distribution of the solar-type stars with high X-ray luminosity from grand-based photometric and spectroscopic observations. We found that some of active solar-type stars have the rotation velocity of < 5 km/s.
We also studied the statistical properties of superflares on active solar-type stars by using the Kepler 1-min cadence data. We found a clear correlation between the duration of flares and the energy released by flares. This correlation can be explained if we assume that flares are caused by the magnetic reconnection.

Research Products

• [Journal Article] Starspot activity and superflares on solar-type stars (2017)
  • Author(s): Maehara, H., Notsu, Y., Notsu, S., Namekata, K., Honda, S., Ishii, T., T., Nogami, D., and Shibata, K.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 印刷中 Issue: 3 Pages: 41-41
  • DOI: 10.1093/pasj/psx013
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Spectroscopic observations of active solar-analog stars with high X-ray luminosity, as a proxy of superflare stars (2017)
  • Author(s): Notsu, Y., Honda, S., Maehara, H., Notsu, S., Namekata, K., Nogami, D., and Shibata, K.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 69 Issue: 1 Pages: 12-12
  • DOI: 10.1093/pasj/psw116
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] High dispersion spectroscopy of solar-type superflare stars. III. Lithium abundances (2015)
  • Author(s): Honda, Satoshi; Notsu, Yuta; Maehara, Hiroyuki; Notsu, Shota; Shibayama, Takuya; Nogami, Daisaku; Shibata, Kazunari
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 67 Issue: 5
  • DOI: 10.1093/pasj/psv054
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] High dispersion spectroscopy of solar-type superflare stars. II. Stellar rotation, starspots, and chromospheric activities (2015)
  • Author(s): Notsu, Yuta; Honda, Satoshi; Maehara, Hiroyuki; Notsu, Shota; Shibayama, Takuya; Nogami, Daisaku; Shibata, Kazunari
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 67 Issue: 3
  • DOI: 10.1093/pasj/psv002
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] High-dispersion spectroscopy of solar-type superflare stars. I. Temperature, surface gravity, metallicity, and vsin i (2015)
  • Author(s): Notsu, Y., Honda, S.,Maehara, H., Notsu, S., Shibayama, T., Nogami, D., Shibata, K.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: - Issue: 3 Pages: 32-32
  • DOI: 10.1093/pasj/psv001
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Statistical properties of superflares on solar-type stars based on 1-min cadence data (2015)
  • Author(s): Maehara, H.; Shibayama, T.; Notsu, Y.; Notsu, S.; Honda, S.; Nogami, D.; Shibata, K.
  • Journal Title: Earth, Planets and Space Volume: 67 Issue: 1
  • DOI: 10.1186/s40623-015-0217-z
  • NAID: 120005756325
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Two sun-like superflare stars rotating as slow as the Sun* (2014)
  • Author(s): Nogami, D., Notsu, Y., Honda, S., Maehara, H., Notsu, S., Shibayama, T., Shibata, K.
  • Journal Title: Publications of the Astronomical Society of Japa Volume: 66 Issue: 2
  • DOI: 10.1093/pasj/psu012
  • NAID: 40020090647
  • Peer Reviewed / Open Access
• [Journal Article] Superflare Occurrence and Energies on G-, K-, and M-type Dwarfs (2014)
  • Author(s): Candelaresi, S., Hillier, A., Maehara, H., Brandenburg, A., Shibata, K.
  • Journal Title: The Astrophysical Journal Volume: 792 Issue: 1 Pages: 67-67
  • DOI: 10.1088/0004-637x/792/1/67
  • Peer Reviewed / Open Access
• [Presentation] G,K,M型星におけるフレアと恒星黒点の関係 (2017)
  • Author(s): 前原裕之
  • Organizer: 日本天文学会2017年春季年会
  • Place of Presentation: 九州大学（福岡県福岡市）
  • Year and Date: 2017-03-15
• [Presentation] Solar /Stellar Flares on K-M dwarfs (2016)
  • Author(s): Maehara, H.
  • Organizer: Impact of Exoplanetary Space Weather On Climate and Habitability
  • Place of Presentation: New Orleans, U.S.A.
  • Year and Date: 2016-11-29
  • Int'l Joint Research / Invited
• [Presentation] Starspot activity and superflares on solar-type stars (2016)
  • Author(s): Maehara, H.
  • Organizer: IAU Symposium 328 "Living Around Active Stars"
  • Place of Presentation: Maresias, Brazil
  • Year and Date: 2016-10-17
  • Int'l Joint Research / Invited
• [Presentation] 太陽型星における巨大黒点の発生頻度とスーパーフレアとの関係 (2016)
  • Author(s): 前原裕之
  • Organizer: 日本天文学会2016年春季年会
  • Place of Presentation: 首都大学東京（東京都）
  • Year and Date: 2016-03-14
• [Presentation] Statistical properties of superflares on solar-type stars (2015)
  • Author(s): Maehara H.
  • Organizer: The First K2 Science Conference
  • Place of Presentation: Santa Barbara, CA, USA
  • Year and Date: 2015-11-02
  • Int'l Joint Research
• [Presentation] 活動的な太陽型星の測光モニター観測 (2015)
  • Author(s): 前原裕之
  • Organizer: 日本天文学会2015年秋季年会
  • Place of Presentation: 甲南大学（兵庫県）
  • Year and Date: 2015-09-09
• [Presentation] Statistical properties of superflares on solar-type stars based on the Kepler 1-min cadence data (2015)
  • Author(s): Maehara, H.; Shibayama, T.; Notsu, Y.; Notsu, S.; Honda, S.; Nogami, D.; Shibata, K.
  • Organizer: XXIX IAU General Assembly / IAU Symposium 320: Solar and Stellar Flares and Their Effects on Planets
  • Place of Presentation: Honolulu, HI, USA
  • Year and Date: 2015-08-03
  • Int'l Joint Research
• [Presentation] Superflares on G-stars discovered with Kepler mission (2015)
  • Author(s): Maehara H.
  • Organizer: VarSITI-SCOSTEP conference: "Superflares and Activity of the Sun in the Cycle Formation Epoch"
  • Place of Presentation: Tel Aviv, Israel
  • Year and Date: 2015-04-28 – 2015-05-01
  • Invited
• [Presentation] Superflares on G-type stars discovered with Kepler mission (2015)
  • Author(s): Maehara, H.
  • Organizer: VarSITI SCOSTEP conference: “Superflares and Activity of the Sun in the Cycle Formation Epoch”
  • Place of Presentation: Tel Aviv, Israel
  • Year and Date: 2015-04-28
  • Int'l Joint Research / Invited
• [Presentation] Statistical Properties of Superflares on Solar-type Stars (2014)
  • Author(s): Maehara H.
  • Organizer: AOGS 11th Annual Meeting
  • Place of Presentation: Sapporo, Japan
  • Year and Date: 2014-07-28 – 2014-08-01
  • Invited
• [Presentation] Statistical properties of superflares on solar-type stars (2014)
  • Author(s): Maehara H.
  • Organizer: SOLAR AND STELLAR FLARES
  • Place of Presentation: Prague, Czech Republic
  • Year and Date: 2014-06-23 – 2014-06-27
  • Invited
• [Presentation] 太陽型星におけるスーパーフレアの統計的性質 (2014)
  • Author(s): 前原裕之
  • Organizer: 日本地球惑星科学連合連合大会2014
  • Place of Presentation: パシフィコ横浜（神奈川県）
  • Year and Date: 2014-04-28 – 2014-05-02