Flows and Non-thermal Velocities in Solar Active Regions Observed with the Extreme-ultraviolet Imaging Spectrometer on Hinode: A Tracer of Active Region Sources of Heliospheric Magnetic Fields?

摘要

From Doppler velocity maps of active regions constructed from spectraobtained by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinodespacecraft we observe large areas of outflow (20-50 km/s) that can persist forat least a day. These outflows occur in areas of active regions that are faintin coronal spectral lines formed at typical quiet Sun and active regiontemperatures. The outflows are positively correlated with non-thermalvelocities in coronal plasmas. The bulk mass motions and non-thermal velocitiesare derived from spectral line centroids and line widths, mostly from a strongline of Fe XII at 195.12 Angstroms. The electron temperature of the outflowregions estimated from an Fe XIII to Fe XII line intensity ratio is about1.2-1.4 MK. The electron density of the outflow regions derived from a densitysensitive intensity ratio of Fe XII lines is rather low for an active region.Most regions average around 7E10+8 cm(-3), but there are variations on pixelspatial scales of about a factor of 4. We discuss results in detail for twoactive regions observed by EIS. Images of active regions in line intensity,line width, and line centroid are obtained by rastering the regions. We alsodiscuss data from the active regions obtained from other orbiting spacecraftthat support the conclusions obtained from analysis of the EIS spectra. Thelocations of the flows in the active regions with respect to the longitudinalphotospheric magnetic fields suggest that these regions might be tracers oflong loops and/or open magnetic fields that extend into the heliosphere, andthus the flows could possibly contribute significantly to the solar wind.