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Chromospheric and Coronal Observations of Solar Flares with the Helioseismic and Magnetic Imager  

Juan Carlos Martinez Oliveros   Submitted: 2013-12-11 12:12

We report observations of white-light ejecta in the low corona, for two X-class flares on the 2013 May 13, using data from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. At least two distinct kinds of sources appeared (chromospheric and coronal), in the early and later phases of flare development, in addition to the white-light footpoint sources commonly observed in the lower atmosphere. The gradual emissions have a clear identification with the classical loop-prominence system, but are brighter than expected and possibly seen here in the continuum rather than line emission. We find the HMI flux exceeds the radio/X-ray interpolation of the bremsstrahlung produced in the flare soft X-ray sources by at least one order of magnitude. This implies the participation of cooler sources that can produce free-bound continua and possibly line emission detectable by HMI. One of the early sources dynamically resembles ''coronal rain'', appearing at a maximum apparent height and moving toward the photosphere at an apparent constant projected speed of 134 ? 8 kms-1. Not much literature exists on the detection of optical continuum sources above the limb of the Sun by non-coronagraphic instruments, and these observations have potential implications for our basic understanding of flare development, since visible observations can in principle provide high spatial and temporal resolution.

Authors: Juan-Carlos Martínez Oliveros, Säm Krucker, Hugh S. Hudson, Pascal Saint-Hilaire, Hazel Bain, Charles Lindsey, Rick Bogart, Sebastien Couvidat, Phil Scherrer, Jesper Schou
Projects: RHESSI,SDO-AIA,SDO-HMI

Publication Status: Accepted for publication in ApJL
Last Modified: 2013-12-11 13:22
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The 2010 August 01 type II burst: A CME-CME Interaction, and its radio and white-light manifestations  

Juan Carlos Martinez Oliveros   Submitted: 2012-02-10 15:25

We present observational results of a type II burst associated with aCME-CME interaction observedin the radio and white-light wavelength range. We applied radiodirection-nding techniques toobservations from the STEREO and Wind spacecraft, the results of whichwere interpreted usingwhite-light coronagraphic measurements for context. The results of themultiple radio-direction ndingtechniques applied were found to be consistent both with each otherand with those derived from thewhite-light observations of coronal mass ejections (CMEs).The resultssuggest that the Type II burstradio emission is causally related to the CMEs interaction.

Authors: Juan Carlos Martínez Oliveros, Claire L. Raftery, Hazel M. Bain, Ying Liu, Vratislav Krupar, Stuart Bale and Säm Krucker
Projects: STEREO

Publication Status: Accepted to ApJ: January 16, 2012
Last Modified: 2012-02-14 12:12
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Imaging Spectroscopy of a White-Light Solar Flare  

Juan Carlos Martinez Oliveros   Submitted: 2011-01-31 23:47

We report observations of a white-light solar flare (SOL2010-06-12T00:57, M2.0) observed by the Helioseismic Magnetic Imager (HMI) on the Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The HMI data give us the first space-based high-resolution imaging spectroscopy of a white-light flare, including continuum, Doppler, and magnetic signatures for the photospheric Fe I line at 6173.34 Å and its neighboring continuum. In the impulsive phase of the flare, a bright white-light kernel appears in each of the two magnetic footpoints. When the flare occurred, the spectral coverage of the HMI filtergrams (six equidistant samples spanning ±172 mÅ around nominal line center) encompassed the line core and the blue continuum sufficiently far from the core to eliminate significant Doppler crosstalk in the latter, which is otherwise a possibility for the extreme conditions in a white-light flare. RHESSI obtained complete hard X-ray and γ-ray spectra (this was the first γ-ray flare of Cycle 24). The Fe I line appears to be shifted to the blue during the flare but does not go into emission; the contrast is nearly constant across the line profile. We did not detect a seismic wave from this event. The HMI data suggest stepwise changes of the line-of-sight magnetic field in the white-light footpoints.

Authors: J. C. Martínez Oliveros, S. Couvidat, J. Schou, S. Krucker, C. Lindsey, H. S. Hudson and P. Scherrer
Projects: RHESSI,SDO-HMI,SDO-EVE

Publication Status: SoPh (Accepted)
Last Modified: 2011-02-01 06:43
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Abstracts by Author
Chromospheric and Coronal Observations of Solar Flares with the Helioseismic and Magnetic Imager
The 2010 August 01 type II burst: A CME-CME Interaction, and its radio and white-light manifestations
Imaging Spectroscopy of a White-Light Solar Flare

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