Absorption Phenomena and a Probable Blast Wave in the 13 July 2004 Eruptive Event

TL;DR

This study analyzes the 2004 solar eruption, revealing absorption phenomena, coronal and Moreton waves, and the dynamics of a CME and blast shock, highlighting the event's complex multi-spectral features and mass movements.

Contribution

It provides a detailed multi-spectral analysis of a solar eruption, identifying absorption phenomena and the independent evolution of CME and blast shock.

Findings

Absorption phenomena linked to falling mass of ~3×10^15 g.

Coronal and Moreton waves decelerated consistent with blast shock motion.

CME lacked a classical three-component structure, with some mass falling back onto the Sun.

Abstract

We present a case study of the 13 July 2004 solar event, in which disturbances caused by eruption of a filament from an active region embraced a quarter of the visible solar surface. Remarkable are absorption phenomena observed in the SOHO/EIT 304 A channel; they were also visible in the EIT 195 A channel, in the H-alpha line, and even in total radio flux records. Coronal and Moreton waves were also observed. Multi-spectral data allowed reconstructing an overall picture of the event. An explosive filament eruption and related impulsive flare produced a CME and blast shock, both of which decelerated and propagated independently. Coronal and Moreton waves were kinematically close and both decelerated in accordance with an expected motion of the coronal blast shock. The CME did not resemble a classical three-component structure, probably, because some part of the ejected mass fell back onto the Sun. Quantitative evaluations from different observations provide close estimates of the falling mass, ~3 10^15 g, which is close to the estimated mass of the CME. The falling material was responsible for the observed large-scale absorption phenomena, in particular, shallow widespread moving dimmings observed at 195 A. By contrast, deep quasi-stationary dimmings observed in this band near the eruption center were due to plasma density decrease in coronal structures.