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

Journal Article · Thu Jan 20 04:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/727/1/L13· OSTI ID:21560561

Brooks, David H ^[1]

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1. College of Science, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)

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.

• OSTI ID: 21560561
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 727; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
ATMOSPHERES
CHEMICAL COMPOSITION
ELEMENTS
IONIZATION POTENTIAL
NONMETALS
SEMIMETALS
SILICON
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CORONA
SOLAR WIND
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
STELLAR WINDS
SULFUR