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Karoff C, Knudsen MF, De Cat P, Bonanno A, Fogtmann-Schulz A, Fu J, Frasca A, Inceoglu F, Olsen J, Zhang Y, Hou Y, Wang Y, Shi J, Zhang W. Observational evidence for enhanced magnetic activity of superflare stars. Nat Commun 2016; 7:11058. [PMID: 27009381 PMCID: PMC4820840 DOI: 10.1038/ncomms11058] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 02/17/2016] [Indexed: 11/22/2022] Open
Abstract
Superflares are large explosive events on stellar surfaces one to six orders-of-magnitude larger than the largest flares observed on the Sun throughout the space age. Due to the huge amount of energy released in these superflares, it has been speculated if the underlying mechanism is the same as for solar flares, which are caused by magnetic reconnection in the solar corona. Here, we analyse observations made with the LAMOST telescope of 5,648 solar-like stars, including 48 superflare stars. These observations show that superflare stars are generally characterized by larger chromospheric emissions than other stars, including the Sun. However, superflare stars with activity levels lower than, or comparable to, the Sun do exist, suggesting that solar flares and superflares most likely share the same origin. The very large ensemble of solar-like stars included in this study enables detailed and robust estimates of the relation between chromospheric activity and the occurrence of superflares. Superflares are large explosive events on stellar surfaces, much larger than solar flares, but it remains unclear whether they share the same origin. Here, the authors analysed 48 superflare stars and determine the relation between their chromospheric activity and the occurrence of superflares.
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Affiliation(s)
- Christoffer Karoff
- Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, 8000 Aarhus C, Denmark.,Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
| | - Mads Faurschou Knudsen
- Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, 8000 Aarhus C, Denmark
| | - Peter De Cat
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussel, Belgium
| | - Alfio Bonanno
- INAF-Osservatorio Astrofisico di Catania, via S.Sofia 78, 95123 Catania, Italy
| | | | - Jianning Fu
- Department of Astronomy, Beijing Normal University, 19 Avenue Xinjiekouwai, Beijing 100875, China
| | - Antonio Frasca
- INAF-Osservatorio Astrofisico di Catania, via S.Sofia 78, 95123 Catania, Italy
| | - Fadil Inceoglu
- Department of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, 8000 Aarhus C, Denmark
| | - Jesper Olsen
- AMS, 14C Dating Centre, Department of Physics, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
| | - Yong Zhang
- Nanjing Institute of Astronomical Optics and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Nanjing 210042, China
| | - Yonghui Hou
- Nanjing Institute of Astronomical Optics and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Nanjing 210042, China
| | - Yuefei Wang
- Nanjing Institute of Astronomical Optics and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Nanjing 210042, China
| | - Jianrong Shi
- Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
| | - Wei Zhang
- Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
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