Nanoflare Activity In the Solar Chromosphere

D. B. Jess*, M. Mathioudakis, P. H. Keys

*Corresponding author for this work

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Abstract

We use ground-based images of high spatial and temporal resolution to search for evidence of nanoflare activity in the solar chromosphere. Through close examination of more than 1 x 10(9) pixels in the immediate vicinity of an active region, we show that the distributions of observed intensity fluctuations have subtle asymmetries. A negative excess in the intensity fluctuations indicates that more pixels have fainter-than-average intensities compared with those that appear brighter than average. By employing Monte Carlo simulations, we reveal how the negative excess can be explained by a series of impulsive events, coupled with exponential decays, that are fractionally below the current resolving limits of low-noise equipment on high-resolution ground-based observatories. Importantly, our Monte Carlo simulations provide clear evidence that the intensity asymmetries cannot be explained by photon-counting statistics alone. A comparison to the coronal work of Terzo et al. suggests that nanoflare activity in the chromosphere is more readily occurring, with an impulsive event occurring every similar to 360 s in a 10,000 km(2) area of the chromosphere, some 50 times more events than a comparably sized region of the corona. As a result, nanoflare activity in the chromosphere is likely to play an important role in providing heat energy to this layer of the solar atmosphere.

Original languageEnglish
Number of pages8
JournalAstrophysical Journal
Volume795
Issue number2
Early online date28 Oct 2014
DOIs
Publication statusPublished - 10 Nov 2014

Keywords

  • methods: numerical
  • Sun: activity
  • Sun: chromosphere
  • Sun: flares
  • WHITE-LIGHT FLARES
  • MAGNETIC RECONNECTION
  • LOWER ATMOSPHERE
  • RAY TELESCOPE
  • OSCILLATIONS
  • REGION
  • EMISSION
  • CORONA
  • DRIVEN

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