Current Sheet Evolution in the Aftermath of a CME Event

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Abstract
We report on SOHO UVCS observations of the coronal restructuring following a coronal mass ejection (CME) on 2002 November 26, at the time of a SOHO-Ulysses quadrature campaign. Starting about 1.5 hr after a CME in the northwest quadrant, UVCS began taking spectra at 1.7 R� , covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 8 line of (Fe xviii), indicating temperatures above 6 ; 106 K, was observed throughout the campaign in a spatially limited location. Comparison with EITimages shows the (Fe xviii) emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a current sheet overlying the arcade. Analysis of the (Fexviii) emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of ourobservations:inparticular,wegivethetemperatureversustimeinthecurrentsheetandestimateitsdensity.Atthe timeofthequadrature,UlysseswasdirectlyabovethelocationoftheCMEandinterceptedtheejecta.Highionization state Fe was detected by the Ulysses SWICS throughout the magnetic cloud associated with the CME, although its rapid temporal variation suggests bursty, rather than smooth, reconnection in the coronal current sheet. The SOHO- Ulyssesdatasetprovideduswiththeuniqueopportunityofanalyzingacurrentsheetstructurefromitslowest coronal levels out to its in situ properties. Both the remote and in situ observations are compared with predictions of theoretical CME models.