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Title: RE-INTERPRETATION OF SUPRA-ARCADE DOWNFLOWS IN SOLAR FLARES

Abstract

Following the eruption of a filament from a flaring active region, sunward-flowing voids are often seen above developing post-eruption arcades. First discovered using the soft X-ray telescope aboard Yohkoh, these supra-arcade downflows (SADs) are now an expected observation of extreme ultra-violet and soft X-ray coronal imagers and spectrographs (e.g, TRACE, SOHO/SUMER, Hinode/XRT, SDO/AIA). Observations made prior to the operation of AIA suggested that these plasma voids (which are seen in contrast to bright, high-temperature plasma associated with current sheets) are the cross-sections of evacuated flux tubes retracting from reconnection sites high in the corona. The high temperature imaging afforded by AIA's 131, 94, and 193 Angstrom-Sign channels coupled with the fast temporal cadence allows for unprecedented scrutiny of the voids. For a flare occurring on 2011 October 22, we provide evidence suggesting that SADs, instead of being the cross-sections of relatively large, evacuated flux tubes, are actually wakes (i.e., trailing regions of low density) created by the retraction of much thinner tubes. This re-interpretation is a significant shift in the fundamental understanding of SADs, as the features once thought to be identifiable as the shrinking loops themselves now appear to be 'side effects' of the passage of the loops throughmore » the supra-arcade plasma. In light of the fact that previous measurements have attributed to the shrinking loops characteristics that may instead belong to their wakes, we discuss the implications of this new interpretation on previous parameter estimations and on reconnection theory.« less

Authors:
 [1];  [2];  [3]
  1. NASA/Goddard Space Flight Center (Oak Ridge Associated Universities), 8800 Greenbelt Rd Code 671, Greenbelt, MD 20771 (United States)
  2. Department of Physics, Montana State University, P.O. Box 173840, Bozeman, MT 59717-3840 (United States)
  3. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS 58, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22047982
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 747; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; GAMMA ASTRONOMY; HOT PLASMA; MAGNETIC RECONNECTION; MASS; OPERATION; SOFT X RADIATION; SOLAR CORONA; SOLAR FLARES; SUN; TOPOLOGY; ULTRAVIOLET RADIATION; VISIBLE RADIATION

Citation Formats

Savage, Sabrina L, McKenzie, David E, and Reeves, Katharine K. RE-INTERPRETATION OF SUPRA-ARCADE DOWNFLOWS IN SOLAR FLARES. United States: N. p., 2012. Web. doi:10.1088/2041-8205/747/2/L40.
Savage, Sabrina L, McKenzie, David E, & Reeves, Katharine K. RE-INTERPRETATION OF SUPRA-ARCADE DOWNFLOWS IN SOLAR FLARES. United States. https://doi.org/10.1088/2041-8205/747/2/L40
Savage, Sabrina L, McKenzie, David E, and Reeves, Katharine K. 2012. "RE-INTERPRETATION OF SUPRA-ARCADE DOWNFLOWS IN SOLAR FLARES". United States. https://doi.org/10.1088/2041-8205/747/2/L40.
@article{osti_22047982,
title = {RE-INTERPRETATION OF SUPRA-ARCADE DOWNFLOWS IN SOLAR FLARES},
author = {Savage, Sabrina L and McKenzie, David E and Reeves, Katharine K},
abstractNote = {Following the eruption of a filament from a flaring active region, sunward-flowing voids are often seen above developing post-eruption arcades. First discovered using the soft X-ray telescope aboard Yohkoh, these supra-arcade downflows (SADs) are now an expected observation of extreme ultra-violet and soft X-ray coronal imagers and spectrographs (e.g, TRACE, SOHO/SUMER, Hinode/XRT, SDO/AIA). Observations made prior to the operation of AIA suggested that these plasma voids (which are seen in contrast to bright, high-temperature plasma associated with current sheets) are the cross-sections of evacuated flux tubes retracting from reconnection sites high in the corona. The high temperature imaging afforded by AIA's 131, 94, and 193 Angstrom-Sign channels coupled with the fast temporal cadence allows for unprecedented scrutiny of the voids. For a flare occurring on 2011 October 22, we provide evidence suggesting that SADs, instead of being the cross-sections of relatively large, evacuated flux tubes, are actually wakes (i.e., trailing regions of low density) created by the retraction of much thinner tubes. This re-interpretation is a significant shift in the fundamental understanding of SADs, as the features once thought to be identifiable as the shrinking loops themselves now appear to be 'side effects' of the passage of the loops through the supra-arcade plasma. In light of the fact that previous measurements have attributed to the shrinking loops characteristics that may instead belong to their wakes, we discuss the implications of this new interpretation on previous parameter estimations and on reconnection theory.},
doi = {10.1088/2041-8205/747/2/L40},
url = {https://www.osti.gov/biblio/22047982}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 747,
place = {United States},
year = {Sat Mar 10 00:00:00 EST 2012},
month = {Sat Mar 10 00:00:00 EST 2012}
}