skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29

Abstract

The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramaty High Energy Solar Spectroscopic Imager . We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe ii chromospheric emission line profiles observed in the impulsive phase.

Authors:
 [1]; ;  [2];  [3];  [4]
  1. Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, 2000 Colorado Ave, Boulder, CO 80305 (United States)
  2. NASA/Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States)
  3. INAF-Osservatorio Astrofisico di Arcetri, I-50125 Firenze (Italy)
  4. Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, NO-0315 Oslo (Norway)
Publication Date:
OSTI Identifier:
22663876
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 836; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMMETRY; ATMOSPHERES; COMPARATIVE EVALUATIONS; COSMIC ELECTRONS; ELECTRON BEAMS; EMISSION; FLUX DENSITY; FORECASTING; HARD X RADIATION; HEATING; HYDRODYNAMICS; HYDROGEN; LAYERS; LIMITING VALUES; RADIANT HEAT TRANSFER; RECOMBINATION; SIMULATION; SOLAR FLARES; SUN; ULTRAVIOLET RADIATION

Citation Formats

Kowalski, Adam F., Allred, Joel C., Daw, Adrian, Cauzzi, Gianna, and Carlsson, Mats, E-mail: Adam.Kowalski@lasp.colorado.edu. The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29. United States: N. p., 2017. Web. doi:10.3847/1538-4357/836/1/12.
Kowalski, Adam F., Allred, Joel C., Daw, Adrian, Cauzzi, Gianna, & Carlsson, Mats, E-mail: Adam.Kowalski@lasp.colorado.edu. The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29. United States. doi:10.3847/1538-4357/836/1/12.
Kowalski, Adam F., Allred, Joel C., Daw, Adrian, Cauzzi, Gianna, and Carlsson, Mats, E-mail: Adam.Kowalski@lasp.colorado.edu. Fri . "The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29". United States. doi:10.3847/1538-4357/836/1/12.
@article{osti_22663876,
title = {The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. I. Modeling the Brightest NUV Footpoints in the X1 Solar Flare of 2014 March 29},
author = {Kowalski, Adam F. and Allred, Joel C. and Daw, Adrian and Cauzzi, Gianna and Carlsson, Mats, E-mail: Adam.Kowalski@lasp.colorado.edu},
abstractNote = {The 2014 March 29 X1 solar flare (SOL20140329T17:48) produced bright continuum emission in the far- and near-ultraviolet (NUV) and highly asymmetric chromospheric emission lines, providing long-sought constraints on the heating mechanisms of the lower atmosphere in solar flares. We analyze the continuum and emission line data from the Interface Region Imaging Spectrograph (IRIS) of the brightest flaring magnetic footpoints in this flare. We compare the NUV spectra of the brightest pixels to new radiative-hydrodynamic predictions calculated with the RADYN code using constraints on a nonthermal electron beam inferred from the collisional thick-target modeling of hard X-ray data from Reuven Ramaty High Energy Solar Spectroscopic Imager . We show that the atmospheric response to a high beam flux density satisfactorily achieves the observed continuum brightness in the NUV. The NUV continuum emission in this flare is consistent with hydrogen (Balmer) recombination radiation that originates from low optical depth in a dense chromospheric condensation and from the stationary beam-heated layers just below the condensation. A model producing two flaring regions (a condensation and stationary layers) in the lower atmosphere is also consistent with the asymmetric Fe ii chromospheric emission line profiles observed in the impulsive phase.},
doi = {10.3847/1538-4357/836/1/12},
journal = {Astrophysical Journal},
number = 1,
volume = 836,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2017},
month = {Fri Feb 10 00:00:00 EST 2017}
}