Plasma outflows from active regions: Are they sources of the slow solar wind?

VAN DRIEL-GESZTELYI, L.; CULHANE, J.L.; BAKER, D.; DÉMOULIN, P.; MANDRINI, C.H.; DEROSA, M.L.; ROUILLARD, A.P.; OPITZ, A.; STENBORG, G.; VOURLIDAS, A.; BROOKS, D.H.

Beijing

Congreso; IAU XXVIII General Assembly - JD 3; 2012

IAU

During 2-18 January 2008 a pair of low-latitude opposite polarity coronal holes were observed on the Sun with two ARs and the heliospheric plasma sheet located between them. We use the Hinode/ EIS to locate AR-related outflows and measure their velocities. STEREO imaging is also employed, as are ACE in-situ observations to assess the resulting impacts on the interplanetary solar wind (SW) properties. Magnetic field extrapolations of the two ARs confirm that AR plasma outflows observed with EIS are co-spatial with quasi-separatrix layer locations, including the separatrix of a null point. Global potential field source-surface modeling indicates that field lines in the vicinity of the null point extend up to the source-surface, enabling a part of the EIS plasma upflows access to the SW. We find that similar upflow properties are also observed within closed field regions that do not reach the source surface. We conclude that some of plasma upflows observed with EIS remain confined along closed coronal loops, but that a fraction of the plasma may be released in the slow SW. This suggests that ARs bordering coronal holes can contribute to the slow SW. Analyzing the in-situ data, we conclude that the type of SW present (composition, temperature, speed and first ionization potential bias) depends on the magnetic topology, i.e. whether the AR is fully or partially enclosed by an overlying streamer.