{
  "id": "1504.00074",
  "version": "v1",
  "published": "2015-04-01T00:57:43.000Z",
  "updated": "2015-04-01T00:57:43.000Z",
  "title": "Statistical properties of superflares on solar-type stars based on 1-min cadence data",
  "authors": [
    "Hiroyuki Maehara",
    "Takuya Shibayama",
    "Yuta Notsu",
    "Shota Notsu",
    "Satoshi Honda",
    "Daisaku Nogami",
    "Kazunari Shibata"
  ],
  "comment": "Accepted for for publication in Earth, Planets and Space",
  "categories": [
    "astro-ph.SR",
    "astro-ph.EP"
  ],
  "abstract": "We searched for superflares on solar-type stars using Kepler data with 1 min sampling in order to detect superflares with short duration. We found 187 superflares on 23 solar-type stars whose bolometric energy ranges from the order of $10^{32}$ erg to $10^{36}$ erg. Some superflares show multiple peaks with the peak separation of the order of $100$-$1000$ seconds 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 the occurrence frequency ($dN/dE$) of superflares as a function of flare energy ($E$) shows the power-law distribution ($dN/dE \\propto E^{-\\alpha}$) with $\\alpha \\sim -1.5$ for $10^{33}<E<10^{36}$ erg which is consistent with the previous results. The average occurrence rate of superflares with the energy of $10^{33}$ erg which is equivalent to X100 solar flares is about once in 500-600 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 ($\\tau$) increases with the flare energy ($E$) as $\\tau \\propto E^{0.39\\pm 0.03}$. This can be explained if we assume the time-scale of flares is determined by the Alfv$\\acute{\\rm e}$n time.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-04-01T00:57:43.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "solar-type stars",
      "superflares",
      "cadence data",
      "statistical properties",
      "flare energy"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}