Statistical properties of superflares on solar-type stars based on 1-min cadence data

By Hiroyuki Maehara, Takuya Shibayama, Y. Notsu, S. Notsu, Satoshi Honda, D. Nogami, Kazunari Shibata. Earth, Planets and Space, 2015

189 citations recorded by the source corpus.

We searched for superflares on solar-type stars using Kepler data with 1-min sampling in order to detect superflares with a short duration. We found 187 superflares on 23 solar-type stars whose bolometric energy ranges from the order of 1032 to 1036 erg. Some superflares show multiple peaks with the peak separation of the order of 100 to 1,000 s which is comparable to the periods of quasi-periodic pulsations in solar and stellar flares. Using these new data combined with the results from the data with 30-min sampling, we found that the occurrence frequency (dN/dE) of superflares as a function of flare energy (E) shows the power-law distribution (dN/dE∝E−α) with α∼−1.5 for 1033<E<1036 erg which is consistent with the previous results. The average occurrence rate of superflares with the energy of 1033 erg which is equivalent to X100 solar flares is about once in 500 to 600 years. The upper limit of energy released by superflares is basically comparable to a fraction of the magnetic energy stored near starspots which is estimated from the photometry.We also found that the duration of superflares (τ) increases with the flare energy (E) as τ∝E0.39 ± 0.03. This can be explained if we assume the time scale of flares is determined by the Alfvén time.

Subfields: Astronomy and Astrophysics, Education

View Paper: https://www.semanticscholar.org/paper/194d9a6685cb77b3e420798089e1f08474942f5a

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Citations in the corpus

Do Kepler Superflare Stars Really Include Slowly Rotating Sun-like Stars?—Results Using APO 3.5 m Telescope Spectroscopic Observations and Gaia-DR2 Data (2019, methodology): “Our previous papers (Shibayama et al. 2013; Maehara et al. 2015) pointed out that the frequency distribution of superflares on Sun-like stars and those of solar flares are roughly on the same power-law line.”
THE KEPLER CATALOG OF STELLAR FLARES (2016, background): “For comparison, the Sun has a g−i color of ∼0.6, and a maximum observed flare energy of ∼1032 erg (Emslie et al. 2012).”
MAGNETIC PROPERTIES OF SOLAR ACTIVE REGIONS THAT GOVERN LARGE SOLAR FLARES AND ERUPTIONS (2016, methodology): “…0.05 (correlation coefficient CC=0.81) and t µ Edecay mag 0.41 0.06 (CC=0.69), which is surprisingly consistent with the results of the superflare analysis by Maehara et al. (2015), t µ Eflare flare 0.39 0.03, where tflare and Eflare are the e-folding decay time and bolometric energy, respectively.”
Stellar Flares from the First TESS Data Release: Exploring a New Sample of M Dwarfs (2019, background): “These have X-ray fluxes of about 10−4 W m−2 (Aarnio et al. 2011), corresponding to X-ray energies of 1029 erg (Aarnio et al. 2012) and to bolometric energies of 1031 erg (Maehara et al. 2015).”
Quasi-periodic Pulsations in Solar and Stellar Flares: An Overview of Recent Results (Invited Review) (2016, background): “The time scale for most of these observations is common over many spectral types and compatible with periodicities in solar flares (Maehara et al., 2015).”