Observations of a post-flare radio burst in X-rays

By using a combination of X-ray (HXIS), Hc~ (Haleakala), white-light corona (Solwind), and zodiacal light (Helios) images on 21-22 May, 1980 we demonstrate, and try to explain, the co-existence of a coronal mass ejection with a stationary post-flare coronal arch. The mass ejection was seen, both by S olwind and Helios, in prolongation of the path of a powerful spray, whereas the active region filament did not erupt. A tentative comparison is made with other occurrences of stationary, or quasi-stationary post-flare coronal arches.

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“…5 -8 . 0 keV, after having integrated the X-ray counts for 25 m i n (Svestka et al, 1982a). Still, it was a clearly defined structure (ef.…”

Section: The Stationary Archmentioning

confidence: 99%

Coronal mass ejection associated with the stationary post-flare arch of 21–22 May 1980

et al. 1986

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“…Therefore, the X-ray data on May 21 are certainly worth a detailed study. Svestka et al (1982a; further abbreviated as SV(a)) measured the time variation of the altitude of the loop tops and the speed of their rise through the corona, but this was only a secondary product of their analysis. The main aim was to demonstrate the existence of a post-flare coronal arch above the active region, different from the loops.…”

Section: Introductionmentioning

confidence: 99%

Hard X-ray images of possible reconnection in the flare of 21 May, 1980

Švestka

Poletto

1985

Sol Phys

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An analysis of the growth of X-ray loops in the flare of 21 May, 1980, observed by HXI S on board SMM spacecraft, has been carried out with high time resolution in six energy channels from 3.5 to 30 keV. This analysis has revealed that the tops of the loops stay for minutes at a given altitude before, quite abruptly, other loop tops begin to appear above them. One of the jumps in altitude, from ~ 27 000 to ~ 45 000 km if the loops extended radially, which occurred quite late in the flare development, is studied in detail. The fact that the tops, of higher loops were first seen in the 22-30 keV energy channel, and only minutes later at lower energies, suggests a new release of energy in a very small volume high in the corona. An initial temperature of at least 50 • 106 K is indicated by the data, inside a volume which may not exceed a few hundred km in diameter. A magnetic reconnection of previously distended field lines appears to be a likely candidate for the observed phenomenon.We also give some revised values of the characteristic parameters of the whole system of loops in this flare which has been the topic of several other studies.

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“…Type IV emissions occur late relative to the hard X-ray peak and appear to be connected to some late-phase acceleration (e.g., Švestka et al 1982;Klein et al 1983). They may be related to delayed electron releases of interplanetary electron events in the corona (Klein et al 2005).…”

Section: Radio Emissions From the Acceleration Regionmentioning

confidence: 99%

Flare Observations

Benz

2016

Living Rev Sol Phys

489

317

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Solar flares are observed at all wavelengths from decameter radio waves to gamma-rays beyond 1 GeV. This review focuses on recent observations in EUV, soft and hard X-rays, white light, and radio waves. Space missions such as RHESSI, Yohkoh, TRACE, SOHO, and more recently Hinode and SDO have enlarged widely the observational base. They have revealed a number of surprises: Coronal sources appear before the hard X-ray emission in chromospheric footpoints, major flare acceleration sites appear to be independent of coronal mass ejections, electrons, and ions may be accelerated at different sites, there are at least 3 different magnetic topologies, and basic characteristics vary from small to large flares. Recent progress also includes improved insights into the flare energy partition, on the location(s) of energy release, tests of energy release scenarios and particle acceleration. The interplay of observations with theory is important to deduce the geometry and to disentangle the various processes involved. There is increasing evidence supporting magnetic reconThis article is a revised version of https://doi.org/10.12942/lrsp-2008-1. Change summary Major revision, updated and expanded. Change details Significant new results from RHESSI and SDO are included. In particular, Sect. 3.4 on "Emissions from above the coronal source" was added (including two new figures) and Sect. 3.2 on "Coronal hard X-ray sources" was expanded. New observations of flares in white light are reported (replaced Fig. 25 with a movie), as well as recent multi-wavelength observations in radio waves and gamma-rays combined with hard X-rays. Four references were removed and 49 new references added. Arnold O. Benz nection as the basic cause. While this process has become generally accepted as the trigger, it is still controversial how it converts a considerable fraction of the energy into non-thermal particles. Flare-like processes may be responsible for large-scale restructuring of the magnetic field in the corona as well as for its heating. Large flares influence interplanetary space and substantially affect the Earth's ionosphere. Flare scenarios have slowly converged over the past decades, but every new observation still reveals major unexpected results, demonstrating that solar flares, after 150 years since their discovery, remain a complex problem of astrophysics including major unsolved questions. Electronic supplementary material

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Observations of a post-flare radio burst in X-rays

Cited by 105 publications

References 18 publications

Coronal mass ejection associated with the stationary post-flare arch of 21–22 May 1980

Coronal mass ejection associated with the stationary post-flare arch of 21–22 May 1980

Hard X-ray images of possible reconnection in the flare of 21 May, 1980

Flare Observations

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