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L ow-Speed Solar Wind and New Classification of Solar Wind

L ow-Speed Solar Wind and New Classification of Solar Wind. Weekly Magnetic G roup Meeting Sept. 9, 2011. 1. Historic view of ambient solar wind. 1960s V < 400km/s Entire coronal base through isotropically thermal expansion

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L ow-Speed Solar Wind and New Classification of Solar Wind

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  1. Low-Speed Solar Wind and New Classification of Solar Wind Weekly Magnetic Group Meeting Sept. 9, 2011

  2. 1. Historic view of ambient solar wind • 1960s V < 400km/s Entire coronal base through isotropically thermal expansion • 1970s V > 600 km/s Coronal holes • 1980s-- Two state: slow, outside coronal hole fast, coronal holes

  3. 2. Two states of ambient solar wind High-speed or fast > V < Low-speed or slow low electron T high electron T low charge-state ratio high charge-state ratio low element ratio high element ratio quasi-steady quasi-trensient? coronal hole Outside coronal hole?? coronal plums coronal loops V=750*, 600, 500, 450, 400*, 300???

  4. 3. Questions 3.1 Where to separate the two states of solar wind? 3.2 Is The different charge-state ratio and element ratio caused by identical physical process?

  5. 4. Suggested sources of low-speed wind The origin of low-speed wind is a subject of much ongoing debate 1. Streamer belt (Zhao & Hundhausen, 1981; Borrini et al., 1981; Sheeley et al., 1997) 2. Pseudo-streamer belt (Bala & Zhao, 2005; Luhmann et al., 2010; Crooker et al., 2011) 3. Active-region coronal holes (Kojima et al., 1999; Wang , 2009) 4. Active-region boundaries (Neugebauer et al., 2002; Brook and Warren, 2011) 5. Closed coronal loops (Feldman et al., 2005) 6. Interchange reconnection (Crooker, 1994; … Crooker et al., 2011)

  6. 5. Theoretical Context • Sources 1, 2, 3 are associated with models based on open field expansion properties that depend on the large expansion rate near the Sun and large magnetic field at coronal base, which determine heating rate and height. It can explain all properties of slow wind except quasi-transient (Wang et al, 2009). • Sources 4, 5, 6 are associated with time-varying processes based on closed loop’s disintegration by “media diffusion”, and open-field reorganization through interchange reconnection (Axford, 1977; Fisk et al, 1999a;b).

  7. 6. New classification of solar wind • The existence of slow wind from low-latitude coronal holes (Wang et al, 2009) implies the existence of the quasi-steady, in addition to the quasi-transient, slow wind. • Solar wind may be classified into quasi-steady streams from open field lines and quasi-transient slow wind from closed field lines adjacent to open field lines

  8. Can Shear instability or Kelvin-Helmholtz instability • transform the slow wind from quasi-steady to • quasi-transient state?

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