Widespread Nanoflare Variability Detected with Hinode/X-Ray Telescope in a Solar Active Region

Marco Miceli, Fabio Reale, Sergio Terzo, Saku Tsuneta, James A. Klimchuk, Fabio Reale, Ryouhei Kano, Marco Miceli, Sergio Terzo

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

It is generally agreed that small impulsive energy bursts called nanoflares are responsible for at least some of the Sun's hot corona, but whether they are the explanation for most of the multimillion-degree plasma has been a matter of ongoing debate. We present here evidence that nanoflares are widespread in an active region observed by the X-Ray Telescope on board the Hinode mission. The distributions of intensity fluctuations have small but important asymmetries, whether taken from individual pixels, multipixel subregions, or the entire active region. Negative fluctuations (corresponding to reduced intensity) are greater in number but weaker in amplitude, so that the median fluctuation is negative compared to a mean of zero. Using Monte Carlo simulations, we show that only part of this asymmetry can be explained by Poisson photon statistics. The remainder is explainable through a tendency for exponentially decreasing intensity, such as would be expected from a cooling plasma produced from a nanoflare. We suggest that nanoflares are a universal heating process within active regions.
Original languageEnglish
Pages (from-to)111-
Number of pages8
JournalTHE ASTROPHYSICAL JOURNAL
Volume736
Publication statusPublished - 2011

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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