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One of the most interesting discoveries of the X-ray Telescope and EUVImaging Spectrometer (EIS) on board the Hinode solar observatory is thepresence of persistent high temperature high speed outflows from the edges ofactive regions. Measurements by EIS indicate that the outflows reach velocitiesof 50 km/s with spectral line asymmetries approaching 200 km/s. It has beensuggested that these outflows may lie on open field lines that connect to theheliosphere, and that they could potentially be a significant source of theslow speed solar wind. A direct link has been difficult to establish, however.In this letter, we use EIS measurements of spectral line intensities that aresensitive to changes in the relative abundance of Si and S as a result of thefirst ionization potential (FIP) effect, to measure the chemical composition inthe outflow regions of AR 10978 over a period of 5 days in December 2007. Wefind that Si is always enhanced over S by a factor of 3--4. This is generallyconsistent with the enhancement factor of low FIP elements measured in-situ inthe slow solar wind by non-spectroscopic methods. Plasma with a slow wind-likecomposition was therefore flowing from the edge of the active region for atleast 5 days. Furthermore, on December 10--11, when the outflow from thewestern side was favorably oriented in the Earth direction, the Si/S ratio wasfound to match the value measured a few days later by ACE/SWICS. These resultsprovide strong observational evidence for a direct connection between the solarwind, and the coronal plasma in the outflow regions.

Establishing a Connection Between Active Region Outflows and the Solar Wind: Abundance Measurements with EIS/Hinode