Spectroscopic Detection of Reconnection Evidence with Solar-B II. Signature of Flows in MHD simulation Hiroaki ISOBE P.F. Chen *, D. H. Brooks, D. Shiota, and K. Shibata Kwasan and Hida Observatories, Kyoto University * Department of Astronomy, Nanjing University The Fourth Solar-B Science Meeting February 3-5, 2003

Observational evidence of reconnection in the solar corona from Yohkoh and SOHO Cusp-shaped post flare loop (Tsuneta et al. 1992) Loop top hard X-ray source (Masuda et al. 1994) Plasmoid ejection (Shibata et al. 1995) Bi-directional jets in explosive events (Innes et al. 1997) Downflow (McKenzie and Hudson 1999) Inflow (Yokoyama et al. 2001)

Objective of spectroscopic detection of reconnection associated flows More direct evidence for reconnection in the corona Determine the real (not apparent) velocity Impact on the study of reconnection physics –Reconnection rate –Diffusion region/current sheet structure –Petschek, Sweet-Parker, or other?

MHD modeling Based on Chen & Shibata (2000) CME-flare model triggered by emerging flux. 2.5D resistive MHD with heat conduction. Anomalous resistivity Gravitational stratification Chen and Shibata (2000) Shiota et al. (2003) FeXII 195 movie SXT movie

Inflow CME (dimming region) flux rope (prominence) current sheet and reconnection jet Velocity differential emission measure (VDEM) and line profiles are calculated from the result of MHD simulation.

Reconnection inflow Based on the same calculation, Chen et al. (2003) show that the inward motion in the EIT images are apparent motion; real plasma velocity is several times larger than the apparent velocity. Yokoyama et al observation simulation

Example of VDEM and line profile Line of sight VDEM (V=0 ～ ±150 km/s Fe XII 195 line profile Fe XII 195 line profile (resolution= 23mA)

Pseudo 3 dimensional view

Pseudo 3D view of blue and red shift components total Fe XII -30km/s blue shift 30km/s red shift inflow outflow (CME) Inflows are seen as red and blue shifted converging flows just above the postflare loops/arcades

Summary of inflow Giant arcades in quiet regions Size: (arcsec), Velocity (km/s) Temperature 1-2 (MK), Emission Measure (cm -5 ) Essential spatial resolution (arcsec) Essential temporal resolution (sec) Flares in active region (11 M in C in 1995) Size: (arcsec), Velocity (km/s) Temperature 3-5MK, Emission Measure (cm -5 ) Essential spatial resolution 1-20 (arcsec) Essential temporal resolution (sec) It is difficult to distinguish inflows components from outflow (CME) components. Inflows can be recognized as blue and red shifted converging flows just above postflare loops/arcades.

Reconnection jet/outflow and current sheet Reconnection jet –bi-directional jet from X-point (diffusion region) –velocity nearly Alfven velocity ( ～ km/s) –slow and fast shocks X-point is dark in any line =>inconsistent with observations of explosive events (Innes et al. 1997) Ca XVII Fe XII

The physical process of magnetic reconnection is not well understood. –Classical resistivity is too small to drive flares via Sweet-Paerker type reconnection. –Petschek type fast reconnection occurs when resistivity is localized. But the origin of anomalous resistivity is not clarified yet. Microscopic scale (<100 cm) is much smaller than the scale of pehnometa ( ～ 10 9 cm) Recent scenario –Sweet-Parker reconnection => tearing instability =>plasmoid ejection => fast reconnection (Tanuma et al. 2001) –Turbulent or fractal current sheet (Shibata and Tanuma 2001) –Effectively large resistivity =>S-P like reconnection

Line profiles of jet in Petschek and Sweet- Parker reconnection Line of sight Petschek Sweet-Parker Doppler shift changes suddenly across the diffusion region Doppler shift changes continuously in the current sheet

Turbulent current sheet The current sheet can be highly turbulent due to tearing instability and plasmoid (magnetic island) formation/ejection. If so, non-thermal broadening will be observed. Another possibility is that the ion temperature than the electron temperature.

Summary of jet/current sheet Giant arcades in quiet region Length: ?-200 (arcsec) Width: ? Velocity: km/s Temperature: 3-5 (MK) Emission Measure: ? cm -5 Essential spatial resolution: ?-20 (arcsec) Essential tempoal resolution: ?-1000 (sec) Flares in active region Length: ?-100 arcsec Width: ? Velocity: (km/s) Temperature: (MK) Emission Measure: ? (cm -5 ) Essential spatial resolution: ?-10 (arcsec) Essential temporal resolution: ?-100 (sec)

Conclusions For inflows, spatial relation ship with postflare loops (arcades) and ejecta is important to distinguish from outflow materials. =>coordinated observation with XRT Detection of reconnection jets and current sheets is more challenging task, but has a large impact on space and laboratory plasma physics. Giant arcade formation is an interesting target for EIS and XRT observations from the viewpoint of reconnection physics –time scale is long –large => spatial resolution –less affected by ambient plasma

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