Suppression of Hydrogen Emission in an X-Class White-Light Solar Flare

Ondrej Prochazka, Ryan O. Milligan, Joel C. Allred, Adam F. Kowalski, Pavel Kotrc, Michail Mathioudakis

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Abstract

We present unique NUV observations of a well-observed X-class flare from NOAA 12087 obtained at Ond\v{r}ejov Observatory. The flare shows a strong white-light continuum but no detectable emission in the higher Balmer and Lyman lines. RHESSI and Fermi observations indicate an extremely hard X-ray spectrum and gamma-ray emission. We use the RADYN radiative hydrodynamic code to perform two type of simulations. One where an energy of 3 x 10^11 erg/cm^2/s is deposited by an electron beam with a spectral index of ~3 and a second where the same energy is applied directly to the photosphere. The combination of observations and simulations allow us to conclude that the white-light emission and the suppression or complete lack of hydrogen emission lines is best explained by a model where the dominant energy deposition layer is located in the lower layers of the solar atmosphere rather than the chromosphere.
Original languageEnglish
Pages (from-to)46-54
JournalThe Astrophysical Journal
Volume837
Issue number1
DOIs
Publication statusPublished - 01 Mar 2017

Bibliographical note

13 pages

Keywords

  • WHITE-LIGHT FLARES
  • SPECTROSCOPY
  • HYDROGEN LINES
  • Modeling

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