An analysis of very strong events known as 'superflares' observed on stars with masses and temperatures similar to the Sun is presented in Nature this week. Superflares are large releases of (probably magnetic) energy that can be up to 10,000 times more energetic than those seen on our Sun; there is no historical record of superflares on our Sun in the past 2,000 years, and a strong case that there has not been one in the past billion years. The latest findings provide estimates of the occurrence frequency of superflares on different solar-type stars.
Kyoto University solar magnetic activity imaginary picture of super solar flare-type stars
Source: Kyoto University
Monochromatic solar flare of September 7, 2011 was taken at (SMART) of (Hα +1.2 Å Telescope of Hida Observatory
Source: Kyoto University
Detailed study of superflares is hampered by the rareness of these events, but the Kepler satellite provides useful data for analysis as it can watch many stars at once. Using these data, Hiroyuki Maehara and colleagues report observations of 365 superflares, including 101 from slowly rotating solar-type stars, from around 83,000 stars observed over 120 days.
Source: Kyoto University
Monochromatic solar flare of September 7, 2011 was taken at (SMART) of (Hα +1.2 Å Telescope of Hida Observatory
Source: Kyoto University
Detailed study of superflares is hampered by the rareness of these events, but the Kepler satellite provides useful data for analysis as it can watch many stars at once. Using these data, Hiroyuki Maehara and colleagues report observations of 365 superflares, including 101 from slowly rotating solar-type stars, from around 83,000 stars observed over 120 days.
The data indicate that slowly rotating stars (like the Sun) have superflares much less often than rapidly rotating ones. Superflares are thought to be caused by magnetic interactions with so-called hot Jupiters (a class of exoplanets with masses similar to that of Jupiter). However, no such hot Jupiters have been discovered around solar-type stars, which indicates that hot Jupiters associated with superflares are rare, the authors suggest. One characteristic shared by the superflare stars is that they have large starspots (much larger than those on the Sun).
Bradley Schaefer discusses this work in an accompanying News & Views article, and suggests that it is unlikely that our Sun has such events.
Bradley Schaefer (Louisiana State University, Baton Rouge, LA, USA)
Bradley Schaefer discusses this work in an accompanying News & Views article, and suggests that it is unlikely that our Sun has such events.
Contacts and sources:
Hiroyuki Maehara (Kyoto University, Japan)Bradley Schaefer (Louisiana State University, Baton Rouge, LA, USA)
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