SH13B-4111:
Wavelengths for EVE coronal dimming signatures
Monday, 15 December 2014
Hugh S Hudson1, Paulo Jose de Aguiar Simoes2 and Egidijus Kukstas2, (1)University of California Berkeley, Berkeley, CA, United States, (2)University of Glasgow, Glasgow, United Kingdom
Abstract:
The EVE instrument on SDO detects post-flare dimmings, mainly in the spectral regions of Fe IX-XII in its MEGS-A range. We have shown that dimmings occurred in most of the 31 X-class flares that occurred between SDO launch and the end of April 2014. Based upon earlier X-ray observations, we interpret these dimmings as the result of CME mass ejections from the low corona. We can estimate the masses involved in these dimmings by deriving a best pre-event temperature and emission measure in the dimmed region from EVE, and a source volume from AIA images. The dimming for SOL2011-02-15, the first of these events, "peaked" at -3.4% in Fe IX in terms of the pre-event emission from the whole Sun, with smaller relative depletions in higher ionization states of Fe. Because of its high photon throughput, EVE data determine line centroids with precisions of a few km/s equivalent. In the present study we analyze the wavelengths of the dimmed regions, characterizing their displacements from the mean wavelengths as functions of heliographic position, time, event magnitude, and excitation state of Fe.
