HAO Colloquium - David Brooks, NRL

Start Aug 15, 2016 3:00 PM
End Aug 15, 2016 4:00 PM
Broadcast Room CG1-Auditorium

Active region outflows as the source of the slow solar wind

Fast and slow winds flow from the Sun, fill the entire solar system with hot gas, and affect the Earth’s near space environment. The fast wind originates from the Sun’s polar regions, but the source regions of the slow wind have long been debated. One of the most interesting discoveries from Hinode is the presence of persistent high-temperature high-speed upflows from the edges of many active regions (ARs). EUV imaging spectrometer (EIS) measurements indicate that they reach speeds of ~50km/s with a much faster component reaching hundreds of km/s. In one well known AR (10978), plasma with a slow wind-like composition was found to flow from the edge of the AR for at least five days. If these upflows lie on open magnetic field, they could become outflows that connect to the heliosphere, however, this particular AR was completely covered by the closed field of a helmet streamer; requiring a complex escape path that may not be general. Other ARs have been studied that show similar difficulties. Using new measurements from EIS, we have constructed a map of the whole Sun that shows areas where plasma with the same chemical composition as the slow wind is flowing out from the solar atmosphere on open magnetic field lines. This comprehensive observation and analysis allows us to account for most of the mass flux observed at Earth. For these observations, taken near solar maximum, we find that a significant source of the slow solar wind is indeed outflows from the edges of active regions.

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