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Title: Detection of Three-minute Oscillations in Full-disk Ly α Emission during a Solar Flare

Abstract

In this Letter we report the detection of chromospheric 3-minute oscillations in disk-integrated EUV irradiance observations during a solar flare. A wavelet analysis of detrended Ly α (from GOES /EUVS) and Lyman continuum (from Solar Dynamics Observatory ( SDO )/EVE) emission from the 2011 February 15 X-class flare (SOL2011-02-15T01:56) revealed a ∼3 minute period present during the flare’s main phase. The formation temperature of this emission locates this radiation at the flare’s chromospheric footpoints, and similar behavior is found in the SDO /Atmospheric Imaging Assembly 1600 and 1700 Å channels, which are dominated by chromospheric continuum. The implication is that the chromosphere responds dynamically at its acoustic cutoff frequency to an impulsive injection of energy. Since the 3-minute period was not found at hard X-ray (HXR) energies (50–100 keV) in Reuven Ramaty High Energy Solar Spectroscopic Imager data we can state that this 3-minute oscillation does not depend on the rate of energization of non-thermal electrons. However, a second period of 120 s found in both HXR and chromospheric lightcurves is consistent with episodic electron energization on 2-minute timescales. Our finding on the 3-minute oscillation suggests that chromospheric mechanical energy should be included in the flare energy budget, and themore » fluctuations in the Ly α line may influence the composition and dynamics of planetary atmospheres during periods of high activity.« less

Authors:
;  [1];  [2]; ;  [3]
  1. SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom)
  2. ESA Directorate of Science, Operations Department, c/o NASA/GSFC Code 671, Greenbelt, MD 20071 (United States)
  3. Solar Physics Laboratory (Code 671), Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
22654371
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 848; 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; CHROMOSPHERE; DETECTION; ELECTRONS; EMISSION; EXTREME ULTRAVIOLET RADIATION; FLUCTUATIONS; HARD X RADIATION; INJECTION; KEV RANGE; LYMAN LINES; OSCILLATIONS; PLANETARY ATMOSPHERES; RADIANT FLUX DENSITY; SOLAR FLARES; SUN; ULTRAVIOLET RADIATION

Citation Formats

Milligan, Ryan O., Fletcher, Lyndsay, Fleck, Bernhard, Ireland, Jack, and Dennis, Brian R. Detection of Three-minute Oscillations in Full-disk Ly α Emission during a Solar Flare. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA8F3A.
Milligan, Ryan O., Fletcher, Lyndsay, Fleck, Bernhard, Ireland, Jack, & Dennis, Brian R. Detection of Three-minute Oscillations in Full-disk Ly α Emission during a Solar Flare. United States. doi:10.3847/2041-8213/AA8F3A.
Milligan, Ryan O., Fletcher, Lyndsay, Fleck, Bernhard, Ireland, Jack, and Dennis, Brian R. Tue . "Detection of Three-minute Oscillations in Full-disk Ly α Emission during a Solar Flare". United States. doi:10.3847/2041-8213/AA8F3A.
@article{osti_22654371,
title = {Detection of Three-minute Oscillations in Full-disk Ly α Emission during a Solar Flare},
author = {Milligan, Ryan O. and Fletcher, Lyndsay and Fleck, Bernhard and Ireland, Jack and Dennis, Brian R.},
abstractNote = {In this Letter we report the detection of chromospheric 3-minute oscillations in disk-integrated EUV irradiance observations during a solar flare. A wavelet analysis of detrended Ly α (from GOES /EUVS) and Lyman continuum (from Solar Dynamics Observatory ( SDO )/EVE) emission from the 2011 February 15 X-class flare (SOL2011-02-15T01:56) revealed a ∼3 minute period present during the flare’s main phase. The formation temperature of this emission locates this radiation at the flare’s chromospheric footpoints, and similar behavior is found in the SDO /Atmospheric Imaging Assembly 1600 and 1700 Å channels, which are dominated by chromospheric continuum. The implication is that the chromosphere responds dynamically at its acoustic cutoff frequency to an impulsive injection of energy. Since the 3-minute period was not found at hard X-ray (HXR) energies (50–100 keV) in Reuven Ramaty High Energy Solar Spectroscopic Imager data we can state that this 3-minute oscillation does not depend on the rate of energization of non-thermal electrons. However, a second period of 120 s found in both HXR and chromospheric lightcurves is consistent with episodic electron energization on 2-minute timescales. Our finding on the 3-minute oscillation suggests that chromospheric mechanical energy should be included in the flare energy budget, and the fluctuations in the Ly α line may influence the composition and dynamics of planetary atmospheres during periods of high activity.},
doi = {10.3847/2041-8213/AA8F3A},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 848,
place = {United States},
year = {Tue Oct 10 00:00:00 EDT 2017},
month = {Tue Oct 10 00:00:00 EDT 2017}
}