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Title: ESTABLISHING A CONNECTION BETWEEN ACTIVE REGION OUTFLOWS AND THE SOLAR WIND: ABUNDANCE MEASUREMENTS WITH EIS/HINODE

Abstract

One of the most interesting discoveries from Hinode is the presence of persistent high-temperature high-speed outflows from the edges of active regions (ARs). EUV imaging spectrometer (EIS) measurements indicate that the outflows reach velocities of 50 km s{sup -1} with spectral line asymmetries approaching 200 km s{sup -1}. It has been suggested that these outflows may lie on open field lines that connect to the heliosphere, and that they could potentially be a significant source of the slow speed solar wind. A direct link has been difficult to establish, however. We use EIS measurements of spectral line intensities that are sensitive to changes in the relative abundance of Si and S as a result of the first ionization potential (FIP) effect, to measure the chemical composition in the outflow regions of AR 10978 over a 5 day period in 2007 December. We find that Si is always enhanced over S by a factor of 3-4. This is generally consistent with the enhancement factor of low FIP elements measured in situ in the slow solar wind by non-spectroscopic methods. Plasma with a slow wind-like composition was therefore flowing from the edge of the AR for at least 5 days. Furthermore, onmore » December 10 and 11, when the outflow from the western side was favorably oriented in the Earth direction, the Si/S ratio was found to match the value measured a few days later by the Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer. These results provide strong observational evidence for a direct connection between the solar wind, and the coronal plasma in the outflow regions.« less

Authors:
 [1]
  1. College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)
Publication Date:
OSTI Identifier:
21560561
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 727; Journal Issue: 1; Other Information: DOI: 10.1088/2041-8205/727/1/L13; Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CHEMICAL COMPOSITION; IONIZATION POTENTIAL; SILICON; SOLAR CORONA; SOLAR WIND; SULFUR; ATMOSPHERES; ELEMENTS; NONMETALS; SEMIMETALS; SOLAR ACTIVITY; SOLAR ATMOSPHERE; STELLAR ACTIVITY; STELLAR ATMOSPHERES; STELLAR CORONAE; STELLAR WINDS

Citation Formats

Brooks, David H, and Warren, Harry P., E-mail: dhbrooks@ssd5.nrl.navy.mil. ESTABLISHING A CONNECTION BETWEEN ACTIVE REGION OUTFLOWS AND THE SOLAR WIND: ABUNDANCE MEASUREMENTS WITH EIS/HINODE. United States: N. p., 2011. Web. doi:10.1088/2041-8205/727/1/L13.
Brooks, David H, & Warren, Harry P., E-mail: dhbrooks@ssd5.nrl.navy.mil. ESTABLISHING A CONNECTION BETWEEN ACTIVE REGION OUTFLOWS AND THE SOLAR WIND: ABUNDANCE MEASUREMENTS WITH EIS/HINODE. United States. https://doi.org/10.1088/2041-8205/727/1/L13
Brooks, David H, and Warren, Harry P., E-mail: dhbrooks@ssd5.nrl.navy.mil. 2011. "ESTABLISHING A CONNECTION BETWEEN ACTIVE REGION OUTFLOWS AND THE SOLAR WIND: ABUNDANCE MEASUREMENTS WITH EIS/HINODE". United States. https://doi.org/10.1088/2041-8205/727/1/L13.
@article{osti_21560561,
title = {ESTABLISHING A CONNECTION BETWEEN ACTIVE REGION OUTFLOWS AND THE SOLAR WIND: ABUNDANCE MEASUREMENTS WITH EIS/HINODE},
author = {Brooks, David H and Warren, Harry P., E-mail: dhbrooks@ssd5.nrl.navy.mil},
abstractNote = {One of the most interesting discoveries from Hinode is the presence of persistent high-temperature high-speed outflows from the edges of active regions (ARs). EUV imaging spectrometer (EIS) measurements indicate that the outflows reach velocities of 50 km s{sup -1} with spectral line asymmetries approaching 200 km s{sup -1}. It has been suggested that these outflows may lie on open field lines that connect to the heliosphere, and that they could potentially be a significant source of the slow speed solar wind. A direct link has been difficult to establish, however. We use EIS measurements of spectral line intensities that are sensitive to changes in the relative abundance of Si and S as a result of the first ionization potential (FIP) effect, to measure the chemical composition in the outflow regions of AR 10978 over a 5 day period in 2007 December. We find that Si is always enhanced over S by a factor of 3-4. This is generally consistent with the enhancement factor of low FIP elements measured in situ in the slow solar wind by non-spectroscopic methods. Plasma with a slow wind-like composition was therefore flowing from the edge of the AR for at least 5 days. Furthermore, on December 10 and 11, when the outflow from the western side was favorably oriented in the Earth direction, the Si/S ratio was found to match the value measured a few days later by the Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer. These results provide strong observational evidence for a direct connection between the solar wind, and the coronal plasma in the outflow regions.},
doi = {10.1088/2041-8205/727/1/L13},
url = {https://www.osti.gov/biblio/21560561}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 1,
volume = 727,
place = {United States},
year = {Thu Jan 20 00:00:00 EST 2011},
month = {Thu Jan 20 00:00:00 EST 2011}
}