Suppression of Hydrogen Emission in a White-light Solar Flare

Ondrej Prochazka, Ryan Milligan, Joel Allred, Adam Kowalski, Michail Mathioudakis

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We present an analysis of an X-class flare that occurred on 11 June 2014 in active region NOAA 12087 using a newly developed high cadence Image
Selector operated by Astronomical Institute in Ondrejov, Czech Republic. This instrument provides spectra in the 350 - 440 nm wavelength range, which
covers the higher order Balmer lines as well as the Balmer jump at 364 nm. However, no detectable increase in these emissions were detected during
the flare, and support observations from SDO/EVE MEGS-B also show that the Lyman line series and recombination continuum were also suppressed,
particularly when compared to an M-class flare that occurred an hour earlier, and two other X-class flares on the preceding day. The X-class flare under
investigation also showed strong white light emission in SDO/HMI data, as well as an extremely hard electron spectrum ( 3.6), and
-ray emission,
from RHESSI data. This unique combination of datasets allows us to conclude that the white light emission from this flare corresponds to a black body
heated by high-energy electrons (and/or ions), as opposed to optical chromospheric emission from hydrogen.
Original languageEnglish
Number of pages1
Publication statusPublished - May 2016
EventSolar Physics Division Meeting 2016 - University of Colorado, Boulder, United States
Duration: 31 May 201603 Jun 2016


ConferenceSolar Physics Division Meeting 2016
Country/TerritoryUnited States
Internet address




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