Author ORCID Identifier
James McAteer:
https://orcid.org/0000-0003-1493-101X
Document Type
Journal Article
Journal Article Version
Final Version / Publisher's PDF (peer-reviewed)
Publication Date
9-1-2022
Abstract
We studied an X1.6 solar flare produced by NOAA Active Region 12602 on 2014 October 22. The entirety of this event was covered by RHESSI, IRIS, and Hinode/EIS, allowing analysis of the chromospheric response to a nonthermal electron driver. We derived the energy contained in nonthermal electrons via RHESSI spectral fitting and linked the time-dependent parameters of this call to the response in Doppler velocity, density, and nonthermal width across a broad temperature range. The total energy injected was 4.8 x 10(30) erg and lasted 352 s. This energy drove explosive chromospheric evaporation, with a delineation in both Doppler and nonthermal velocities at the flow reversal temperature, between 1.35 and 1.82 MK. The time of peak electron injection (14:06 UT) corresponded to the time of highest velocities. At this time, we found 200 km s(-1) blueshifts in the core of Fe xxiv, which is typically assumed to be at rest. Shortly before this time, the nonthermal electron population had the shallowest spectral index (approximate to 6), corresponding to the peak nonthermal velocity in Si iv and Fe xxi. Nonthermal velocities in Fe xiv, formed near the flow reversal temperature, were low and not correlated with density or Doppler velocity. Nonthermal velocities in ions with similar temperatures were observed to increase and correlate with Doppler velocities, implying unresolved flows surrounding the flow reversal point. This study provides a comprehensive, time-resolved set of chromospheric diagnostics for a large X-class flare, along with a time-resolved energy injection profile, ideal for further modeling studies.
Published in
Astrophysical Journal
DOI
10.3847/1538-4357/ac87a9
Keywords
Solar flares, Solar flare spectra, Solar x-ray flares, Solar extreme ultraviolet emission, Solar ultraviolet emission, Active solar chromosphere, Solar active region velocity fields, Solar activity, Solar chromosphere, Solar transition region
Department / Organizational Unit
Astronomy
Copyright Notice
© 2022 S. Sellers, R. Milligan, & R. McAteer, reuse allowed according to Creative Commons license.
License for Reuse
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Sellers, S. G., Milligan, R. O., & McAteer, R. T. J. (2022). Call and response: A time-resolved study of chromospheric evaporation in a large solar flare. Astrophysical Journal, 936(1). https://doi.org/10.3847/1538-4357/ac87a9