Solar Source and Magnetic Cloud

1. Solar Source and Magnetic Cloud Yang Liu – Stanford University yliu@solar.stanford.edu

2. Erupted filaments in quiet Sun and magnetic cloud • A relationship between erupted filament in the quiet sun and the magnetic cloud has been established. • Pioneer work done by Marubashi (1986), followed by Bothmer & Schwenn (1994), Rust (1994), Bothmer & Rust (1997), Marubashi (1997), Zhao & Hoeksema (1998), McAllister & Martin (2000), and Ruzmaikin et al (2003).

3. Active regions and magnetic clouds • Active region as a whole body: no correlations have been found. • Pudovkin (1977): • 22 cases; IMF orientation agrees with the orientation of the meridional component of the background field in the flaring regions (but used an average of the IMF for those events). • Tang et al (1985): • 12 cases; Shows no correlation between flare field orientation and IMF orientation. • Montana State U. folks (Pevtsov & Canfield, 2001; Leamon et al 2002, 2004): • Pevtsov & Canfield (2001): magnetic structure of individual active region plays a role in geomagnetic events; • Leamon et al (2002): 46 events from sigmoidal active regions. Only 70% of them have the same handedness with magnetic clouds (For erupted filaments in quiet sun, 95% agreement was found); • Leamon et al (2004): 12 events with vector magnetograms available. Fluxes of AR and MC are comparable; electric currents of them are different in orders; twists of them are different in one order (AR’s is one order smaller than MC’s); no correlations for handedness.

4. Active regions and magnetic cloud • The erupted filaments in AR and magnetic clouds: limited case study cannot establish a correlation. • Webb et al (2000): • May 12 1997 event; • Filament defines orientation and handedness; • Dimming areas define footpoints of the modeled rope • Agreement was found between the filament and MC in terms of orientation, handedness and flux. • Yurchyshyn et al (2001): • Two cases; • Filament defines orientation, LFFF defines handedness; • Agreement was found between the filaments and MCs.

5. Active regions and magnetic cloud • Post-flare arcades and magnetic clouds: a relationship has not yet been established. • Yurchyshyn et al (2005): • Two cases (Oct 28 2003 and Nov. 18, 2003); • 50% agreement.

6. Active regions, CMEs and magnetic clouds • A correlation has not yet been established. • Krall et al (2006): • Only one case (Oct. 28, 2003); • Chen J. flux rope model (1996); • LASCO images to define flux rope parameters; • NL orientation to define twist; AR size to define distance of footpoints of flux rope. • Yurchyshyn et al (2006; 2007): • LASCO images to define orientation of flux rope. • Agreement between modeled flux rope orientation and magnetic cloud is at a level of 67% in a sample of 25 events.

7. Summary • A good relationship has been established between the erupted filaments in the quiet sun and the magnetic clouds; • There is still a long way to go to recover a whole picture between the active regions, flares, CMEs and magnetic clouds.

8. Questions to be addressed to establish a link • Identifying actual erupted flux rope (or field) in active regions; • Filament in AR? Post-flare arcades? Something else? • Distortion & change of magnetic field structure of flux rope during eruption; • For example kink instability (Fan & Gibson 2007). • Coupling the local field and global field; • For example, EIT dimming (global and local; Zhukov et al 2007). • Interaction between the erupted rope and the heliospheric current sheets; • Pioneer work done by Zhao & Hoeksema (1996), followed by Yurchyshyn et al (2006). • Distortion of configuration of flux rope due propagation in the interplanetary space: interaction with ambient solar wind. • Only MHD experiments have been done (Gosling & Riley, 1996; Riley 1997; Odstrcil & Pizzo 1999; Schmidt & Cargill 2001; Riley & Crooker 2004).

9. Dst Dependence on V and B Gonzalez et al., Yurchyshyn et al., Zhang et al……. R2O CMEs measured days before MCs measured min before From Gopalswamy 2007, LWS