Solar flare-related eruptions followed by long-lasting occultation of the emission in the He II 304 A line and in microwaves

TL;DR

This paper investigates solar eruptions that cause long-lasting occultation of emissions in the He II 304 Å line and microwaves, analyzing absorption phenomena and estimating properties of eruptive plasma from multi-frequency observations.

Contribution

It presents detailed analysis of three eruptive solar events, estimating the parameters of absorbing plasma and observing filament destruction and dispersion in the 304 Å line.

Findings

Absorption phenomena observed as negative bursts in microwaves.

Eruption-related filament destruction and dispersion over large areas.

Long-lasting occultation of emissions in He II 304 Å line linked to eruptions.

Abstract

Plasma with a temperature close to the chromospheric one is ejected in solar eruptions. Such plasma can occult some part of emission of compact sources in active regions as well as quiet solar areas. Absorption phenomena can be observed in the microwave range as the so-called 'negative bursts' and also in the He II 304 A line. The paper considers three eruptive events associated with rather powerful flares. Parameters of absorbing material of an eruption are estimated from multi-frequency records of a 'negative burst' in one event. 'Destruction' of an eruptive filament and its dispersion like a cloud over a huge area observed as a giant depression of the 304 A line emission has been revealed in a few events. One such event out of three ones known to us is considered in this paper. Another event is a possibility.