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Variations of flaring kernel sizes in various parts of the Hα line profile  

Krzysztof Radziszewski   Submitted: 2012-11-12 03:39

We analyze the temporal variations of the sizes and emission intensities of thirtyone flaring kernels in various parts of the Hα line profile. We have found that the areas of all kernels decrease systematically when observed in consecutive wavelengths toward the wings of the Hα line, but their areas and emission intensity vary in time. Our results are in agreement with the commonly accepted model of the glass-shaped lower parts of the magnetic flaring loops channelling high energy variable particle beams toward the chromospheric plasma. High time resolution spectral-imaging data used in our work were collected using the Large Coronagraph and Horizontal Telescope equipped with the Multichannel Subtractive Double Pass Spectrograph and the Solar Eclipse Coronal Imaging System (MSDP-SECIS) at the Bialkow Observatory of the University of Wroclaw, Poland.

Authors: K. Radziszewski and P. Rudawy
Projects: SECIS Instrument (Wroclaw)

Publication Status: Accepted for print (5 November 2012) in Solar Physics
Last Modified: 2012-11-14 07:17
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High time resolution observations of solar Hα flares - II Search for signatures of electron beam heating  

Krzysztof Radziszewski   Submitted: 2011-10-20 02:51

Aims. The Hα emission of solar flare kernels and associated hard X-ray (HXR) emission often show similar time variations but their light curves are shifted in time by energy transfer mechanisms. We searched for fast radiative response of the chromosphere in the Hα line as a signature of electron beam heating. Methods. We investigate the time differences with sub-second resolution between the Hα line emission observed with a Multi-channel Subtractive Double Pass (MSDP) spectrograph on the Large Coronagraph and Horizontal Telescope at Bialkow Observatory, Poland, and HXR emission recorded by the RHESSI spacecraft during several flares, greatly extending our earlier analysis (Paper I) to flares between 2003 and 2005. Results. For 16 Hα flaring kernels, observed in 12 solar flares, we made 72 measurements of time delays between local maxima of the RHESSI X-ray and Hα emissions. For most kernels, there is an excellent correlation between time variations in the Hα line emission (at line centre and in the line wings) and HXR (20?50 keV) flux, with the Hα emission following features in the HXR light curves generally by a short time lapse delta-t = 1?2 s, sometimes significantly longer (10?18 s). We also found a strong spatial correlation. Conclusions. Owing to our larger number of time measurements than in previous studies, the distribution of delta-t values shows a much clearer pattern, with many examples of short (1?2 s) delays of the Hα emission, but with some flares showing longer (10?18 s) delays. The former are consistent with energy transfer along the flaring loop legs by non-thermal electron beams, the latter to the passage of conduction fronts.

Authors: K. Radziszewski, P. Rudawy, and K. J. H. Phillips
Projects: SECIS Instrument (Wroclaw)

Publication Status: Article accepted for publication in Section 9. The Sun of Astronomy and Astrophysics. The official date of acceptance is 13/09/2011.
Last Modified: 2012-11-12 03:57
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Subject will be restored when possible  

Krzysztof Radziszewski   Submitted: 2008-05-08 04:14

In this paper we present new results of spectraphotometrical investigations of the flaring kernels sizes and their intensities measured simultaneously in various parts of the Hα line profile. Our investigations were based on the very high temporal resolution spectral-imaging observations of the solar flares collected with Large Coronagraph (LC), Multi-channel Subtractive Double Pass Spectrograph and Solar Eclipse Coronal Imaging System (MSDP-SECIS) at Bialkow Observatory (University of Wroclaw, Poland). We have found that the areas of the investigated individual flaring kernels vary in time and in wavelengths as well as the intensities and areas of the Hα flaring kernels decreased systematically when observed in consecutive wavelengths toward the wings of the Hα line. Our result could be explained as an effect of the cone-shaped lower parts of the magnetic loops channeling high energy particle beams exciting chromospheric plasma.

Authors: K. Radziszewski and P. Rudawy
Projects: None

Publication Status: Paper accepted to print in Annales Geophysicae (Special Issue: SOHO 20 Solar Conference)
Last Modified: 2008-09-23 21:02
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Sizes of flaring kernels in various parts of the Hα line profile  

Krzysztof Radziszewski   Submitted: 2008-05-08 04:14

This abstract was corrupted following database problems and is being recovered. It will be restored as quickly as possible. Any questions, please send them to Alisdair. Sorry for any incovenience.


Authors: K. Radziszewski and P. Rudawy
Projects: MSDP Spectrograph (Wroclaw)

Publication Status: Published in Annales Geophysicae (Special Issue: SOHO 20 Solar Conference)
Last Modified: 2011-10-24 12:56
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Variations of flaring kernel sizes in various parts of the H-alpha line profile
High time resolution observations of solar H-alpha flares - II Search for signatures of electron beam heating
Subject will be restored when possible
Sizes of flaring kernels in various parts of the H-alpha line profile

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