The Relationship Between Magnetic Clouds and Solar Flare/CME Evolution

1. The Relationship Between Magnetic Clouds and Solar Flare/CME Evolution Jiong Qiu Department of Physics Montana State University Canfield-fest, Boulder, CO

2. Outline: • Magnetic Clouds As Flux Ropes: brief history and definition • Solar Surface Activities Associated with MCs - nature of the association - parameters that have been measured • Origin of Interplanetary Flux Rope: - nature or nurture? - observations - model - are we settled? • Conclusion Canfield-fest, Boulder, CO

3. Magnetic Cloud: brief history • 1954 Morrison: unusual magnetized clouds of plasma emitted by the active sun. • 1958 Cocconi et al.: magnetic loop or bottle anchored in the sun. • 1958 Piddington: magnetic bubble detached from the sun by reconnection. • 1959 Gold: shocks preceding these magnetic loops • 1980-81 Burlaga: first coined “magnetic cloud” • 1990, 1997, Lepping: magnetic cloud properties (Burlaga et al, 1981, JGR, 86, 6673-6684) Canfield-fest, Boulder, CO

4. Magnetic Cloud: in-situ measurements Canfield-fest, Boulder, CO

5. Magnetic Cloud: definition Definition: • Tightly wound helix B: 10 - 100 nT • Low temperature and plasma density T: 105 K, n: 10 – 100 cm-3, b: 0.01 – 0.1 • Higher speed than ambient solar wind v: 300 - 800 km s-1 • Preceded by shocks and sheaths (Burlaga et al 1981; Lepping et al. 1990) Canfield-fest, Boulder, CO

6. Magnetic Cloud: interplanetary flux rope From in-situ observations, a flux rope may be reconstructed with various methods. Marubashi (2000) Hu & Sonnerup 2002 Canfield-fest, Boulder, CO

7. Magnetic Cloud: flux rope properties MC fitting methods: Riley et al. (2004), Dasso et al. (2006) MC fitting results: Lepping et al. (2000), Lynch et al. (2005) Canfield-fest, Boulder, CO

8. Solar surface activities: association Surface: 1.0 – 1.1 Rsun CDAW (1996-2005) identified solar source for 88 geomagnetic storms (Dst < -100 nT), 46 being MCs. Zhang et al. (2007) Canfield-fest, Boulder, CO

9. Solar surface activities: association CMEs: link between MCs and solar surface activities. Canfield-fest, Boulder, CO

10. Solar surface activities: physical properties Canfield-fest, Boulder, CO

11. Solar surface activities: a case study An almost catch-all event, the 1997 May 12-15 event, analyzed by Webb et al. (2000, JGR, Vol 105, 27251) Canfield-fest, Boulder, CO

12. Origin of the flux rope: the two tales Canfield-fest, Boulder, CO

13. Origin of the flux rope: pre-existing rope What do we see as a magnetic flux rope? SXT/Yohkoh prominence (HAO) Filaments and sigmoids are magnetized plasma structures present prior to eruption with higher chance of MC occurrence. SXR sigmoid Canfield et al. 2000 Canfield-fest, Boulder, CO

14. Origin of the flux rope: pre-existing rope? Dere et al. (1999): “In conclusion, we do not find evidence in the SOHO data for preexisting helical structure, but we suggest that the flux rope may be formed fairly rapidly during the ejection …” Leamon and Canfield et al. (2004): “These findings compel us to believe that magnetic clouds associated with active region eruptions are formed by magnetic reconnection between these regions and their larger-scale surroundings, rather than simple eruption of preexisting structure in the corona or the chromosphere.” Canfield-fest, Boulder, CO

15. Origin of the flux rope: in-situ formed rope van Ballegooijen & Martens (1989) In-situ formed flux ropeby magnetic reconnection in a sheared arcade, transferring shear to twist. Canfield-fest, Boulder, CO

16. poloidal or azimuthal magnetic flux p: the amount of twist along the field lines in-situ formed flux rope The helical structure, or the twist, results from magnetic reconnection. reconnection Longcope et al (2007) poloidal flux reconnection flux r ribbons toroidal or axial magnetic flux t Canfield-fest, Boulder, CO

17. In-situ formed rope: reconnection & flare BC reconnection Vin dAC BR reconnection rate (general) dAR MDI magnetogram flare at an earlier time flare at a later time dAR measure reconnection from flare evolution: v v model: Forbes & Priest 1984 observation: flares and magnetic fields Canfield-fest, Boulder, CO

18. In-situ formed rope: measurements If assumptions hold, we’re led to compare flare ribbon flux and MC poloidal flux. Canfield-fest, Boulder, CO

19. Fluxes at two ends: observer’s goodwill Canfield-fest, Boulder, CO

20. Fluxes at two ends: magnetic clouds • MC measurements by Hu, Leamon, & Lynch. • - MCs with (squares) or without (diamonds) filament eruption. (Qiu et al. 2007) Canfield-fest, Boulder, CO

21. Fluxes at two ends: flares Hu et al. 02 Leamon et al. 04 Lynch et al. 05 • linearly scaled • comparable • no bimodal pattern w/ or w/o erupting filament • P - r quite relevant • flux rope largely in- situ formed? (Qiu et al. 2007) Canfield-fest, Boulder, CO

22. Fluxes at two ends: CME With similar conservation assumptions, Moore et al. (2007) takes a different approach to infer the mean magnetic field strength at the flare ribbons for limb flares/CMEs and MCs. Canfield-fest, Boulder, CO

23. Fluxes at two ends: dimming New interpretation of coronal dimming as mapping the pre-reconnection stretched arcade , which ultimately joins the poloidal flux (Forbes and Lin 2000, Demoulin 2002), and in cases the measured dimming flux matches the MC poloidal flux (Mandrini et al. 2005, Attrill et al. 2006). Moore et al. (2001) Canfield-fest, Boulder, CO

24. Fluxes at two ends: and from 1.0 - 1.1Rsun The elusive reconnection occurs in the elusive corona! • It provides: • connection from photosphere to corona; • description of pre-reconnection field; • reconnection/post-reconnection topology in principle testable; • relieved from the 2.5D assumption. • Longcope et al. (2007)measure and compute: • helicity buildup • magnetic topology • reconnection flux • helicity transfer • energy release Details in Kazachenko’s talk Canfield-fest, Boulder, CO

25. Relationship between MC and flare/CME Magnetic structure: • MCs are a special group of CMEs reached 1AU. • Flares and CMEs are magnetically related, the keyword being reconnection. Canfield-fest, Boulder, CO

26. Origin of the flux rope: are we settled? • sample limitation: flares being the best manifest of reconnection, we look at flares. • 2D is naïve: what does STEREO see? • Local versus global: • - are all flux ropes created locally? • - does locally formed flux rope know the global field? • During the transport: • - how and how much does the flux rope change on • the way? Canfield-fest, Boulder, CO

27. Origin of the flux rope: STEREO’s view Mostl et al. (2008, 2009) analyzed MCs seen by multiple spacecrafts and solar progenitors, and the conclusions: • Coherent flux rope structure reasonably fitted by the 2D methodology. • A flare-less filament-y MC flux rope: • A flare-y filament-y MC flux rope: Canfield-fest, Boulder, CO

28. Origin of the flux rope: interaction Available means to investigate interaction between locally formed flux ropes with global magnetic field as well as in interplanetary space may include: • Coronal dimming analysis (review by Gibson & Fan 2008) • Improved global field modeling • MHD numerical model • Combined model/observation effort while preserving the key physics Canfield-fest, Boulder, CO

29. Conclusions: We probably have good understanding of a family of flux ropes that are created locally by reconnection during the eruption, and we pass the DNA test that holds the flux and helicity conservation. However, we do not claim to understand all. Among many things we do not follow, the important one is how flux ropes interact with the surroundings during the journey of 1 AU. Canfield-fest, Boulder, CO

30. Conclusions: Canfield et al. (2000) identified areas of future work: Canfield-fest, Boulder, CO