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Title: Explosive Chromospheric Evaporation Driven by Nonthermal Electrons around One Footpoint of a Solar Flare Loop

Abstract

We explore the temporal relationship between microwave/hard X-ray (HXR) emission and Doppler velocity during the impulsive phase of a solar flare on 2014 October 27 (SOL2014-10-27) that displays a pulse on the light curves in the microwave (34 GHz) and HXR (25–50 keV) bands before the flare maximum. Imaging observation shows that this pulse mainly comes from one footpoint of a solar flare loop. The slit of the Interface Region Imaging Spectrograph ( IRIS ) stays at this footpoint during this solar flare. The Doppler velocities of Fe xxi 1354.09 Å and Si iv 1402.77 Å are extracted from the Gaussian fitting method. We find that the hot line of Fe xxi 1354.09 Å (log T ∼ 7.05) in the corona exhibits blueshift, while the cool line of Si iv 1402.77 Å (log T ∼ 4.8) in the transition region exhibits redshift, indicating explosive chromospheric evaporation. Evaporative upflows along the flare loop are also observed in the AIA 131 Å image. To our knowledge, this is the first report of chromospheric evaporation evidence from both spectral and imaging observations in the same flare. Both microwave and HXR pulses are well correlated with the Doppler velocities, suggesting that the chromospheric evaporationmore » is driven by nonthermal electrons around this footpoint of a solar flare loop.« less

Authors:
; ; ;  [1]
  1. Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, CAS, Nanjing 210008 (China)
Publication Date:
OSTI Identifier:
22654473
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 841; 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; EMISSION; EVAPORATION; EXPLOSIVES; GAMMA RADIATION; HARD X RADIATION; INTERFACES; KEV RANGE; MICROWAVE RADIATION; RED SHIFT; SOLAR FLARES; SUN; ULTRAVIOLET RADIATION; VISIBLE RADIATION

Citation Formats

Li, D., Ning, Z. J., Huang, Y., and Zhang, Q. M., E-mail: lidong@pmo.ac.cn. Explosive Chromospheric Evaporation Driven by Nonthermal Electrons around One Footpoint of a Solar Flare Loop. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA71B0.
Li, D., Ning, Z. J., Huang, Y., & Zhang, Q. M., E-mail: lidong@pmo.ac.cn. Explosive Chromospheric Evaporation Driven by Nonthermal Electrons around One Footpoint of a Solar Flare Loop. United States. doi:10.3847/2041-8213/AA71B0.
Li, D., Ning, Z. J., Huang, Y., and Zhang, Q. M., E-mail: lidong@pmo.ac.cn. Sat . "Explosive Chromospheric Evaporation Driven by Nonthermal Electrons around One Footpoint of a Solar Flare Loop". United States. doi:10.3847/2041-8213/AA71B0.
@article{osti_22654473,
title = {Explosive Chromospheric Evaporation Driven by Nonthermal Electrons around One Footpoint of a Solar Flare Loop},
author = {Li, D. and Ning, Z. J. and Huang, Y. and Zhang, Q. M., E-mail: lidong@pmo.ac.cn},
abstractNote = {We explore the temporal relationship between microwave/hard X-ray (HXR) emission and Doppler velocity during the impulsive phase of a solar flare on 2014 October 27 (SOL2014-10-27) that displays a pulse on the light curves in the microwave (34 GHz) and HXR (25–50 keV) bands before the flare maximum. Imaging observation shows that this pulse mainly comes from one footpoint of a solar flare loop. The slit of the Interface Region Imaging Spectrograph ( IRIS ) stays at this footpoint during this solar flare. The Doppler velocities of Fe xxi 1354.09 Å and Si iv 1402.77 Å are extracted from the Gaussian fitting method. We find that the hot line of Fe xxi 1354.09 Å (log T ∼ 7.05) in the corona exhibits blueshift, while the cool line of Si iv 1402.77 Å (log T ∼ 4.8) in the transition region exhibits redshift, indicating explosive chromospheric evaporation. Evaporative upflows along the flare loop are also observed in the AIA 131 Å image. To our knowledge, this is the first report of chromospheric evaporation evidence from both spectral and imaging observations in the same flare. Both microwave and HXR pulses are well correlated with the Doppler velocities, suggesting that the chromospheric evaporation is driven by nonthermal electrons around this footpoint of a solar flare loop.},
doi = {10.3847/2041-8213/AA71B0},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 841,
place = {United States},
year = {Sat May 20 00:00:00 EDT 2017},
month = {Sat May 20 00:00:00 EDT 2017}
}