Energy partition during initial stages of the CME Jiong Qiu Physics Department, Montana State University
Outline: • Outstanding issues • Recent progress • Difficulties
Outstanding issues on energy: • energy storage: is there enough energy? how is this energy stored? • energy release: initiation (trigger) of energy release the form of energy release: kinetic + potential => CMEs (ECME) radiative => flares (Eflare) order-of-magnitudely: ECME ~ Eflare ~ 1029-32 ergs
Progress: what we know so far? • Flares and CMEs: statistics related or not? - fast CMEs are associated with major flares … how? - different manifestations of same process - not a causal relationship energy? - qualitative relation between energy proxies
308 CME-Solar Microwave Burst events from 1996-2001 SMB peak flux (sfu) CME speed (km/s) CMEs (LASCO) vs SMBs (RSTN) (Dougherty et al. 2002)
546 CME-flare events from 1996-2001 CME velocity (LASCO) vs SXR Intensity (GOES 1-8A) CME speed (Vrsnak et al. 2005) CME kinematic energy (proxy) vs SXR Intensity CME energy time integrated SXR intensity
flare SXR CME velocity • Flares and CMEs: some more details closely related CME motion and flare emission in some well observed events (Zhang et al. 2001) The relationship between some flares and CMEs may be closer than we had thought, thus the energy partition becomes a valid question.
flare emission EC C 11 12 13 14 electric field (V/cm) flux rate (1018 Mx/s) Correlated flare non-thermal emission (energy release rate) and magnetic reconnection rate. • Flares and CMEs: possible link Correlated CME/filament acceleration and magnetic reconnection rate in a single event
Flares and CMEs: possible link speed mass k. energy Mcme~ r0.39 Kcme~ r0.89 Vcme~ r0.27 total reconnection flux (1021 Mx) CME speed, mass, and kinetic energy may be scaled with the total reconnection flux. in a group of events
Flares and CMEs: energy? CME k. energy SXR flux Kcme~ r0.89 Fflare ~ r1.17 total reconnection flux (1021 Mx) • flare radiation, CME kinematic energy, and reconnection flux in a number of events: • with or without filament eruptions • in a variety of magnetic configurations in source regions
Summary: what do we think we know? Harrison (1995) “…the flare and CME are signatures of the same magnetic ‘disease’, that is, they represent the responses in different parts of the magnetic structure, to a particular activity; they do not drive one another but are closely related.” • Reconnection governs energy release in flares. • Reconnection restructures the magnetic configuration in such a way that enhances the upward force thus acceleration, or the other way around. flare <==> magnetic reconnection <==> CME
Difficulties: what we do not know? • Reconnection governs energy release in flares. Relationship between reconnection rate and energy release rate is not known. Converting radiation power to energy release rate is difficult.
reconnection and CME acceleration it crucially depends on the relevant magnetic structures and evolution, which are not directly observable. - magnetic structure of CMEs - ambient magnetic field - how is the CME structure formed: e.g. pre- existing and reconnection formed flux rope
Hu et al. 02 Leamon et al. 04 Lynch et al. 05 r - p: reconnection flux and twisted flux in flux ropes • 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)
? Flare <==> CME Correlated events: selection effect? size effect? Not correlated events: different mechanisms? a fat “end” of continuous distribution?