From Gigahertz to Millihertz: A Multiwavelength Study of the Acoustically Active 14 August 2004 M7.4 Solar Flare

Abstract

We carried out an electromagnetic acoustic analysis of the solar flare of 14 August 2004 in active region AR10656 from the radio to the hard X-ray spectrum. The flare was a GOES soft X-ray class M7.4 and produced a detectable sun quake, confirming earlier inferences that relatively low energy flares may be able to generate sun quakes. We introduce the hypothesis that the seismicity of the active region is closely related to the heights of coronal magnetic loops that conduct high-energy particles from the flare. In the case of relatively short magnetic loops, chromospheric evaporation populates the loop interior with ionised gas relatively rapidly, expediting the scattering of remaining trapped high-energy electrons into the magnetic loss cone and their rapid precipitation into the chromosphere. This increases both the intensity and suddenness of the chromospheric heating, satisfying the basic conditions for an acoustic emission that penetrates into the solar interior.

Seismic Transients from Flares in Solar Cycle 23

“…The evidence provided by Martínez-Oliveros et al (2007, 2008b suggests that low lying coronal loops are more likely to be conducive to a more rapid injection of trapped electrons into the chromosphere at their footpoints. This enhances the magnitude and suddenness of the chromospheric heating that gives rise to the intense visible continuum emission seen in all flares with detectable seismic activity.…”

“…They also argued in favour of the need for a source agent that acted relatively suddenly, a qualification further emphasized by Martínez-Oliveros et al (2007, 2008a, who discovered significant seismic emission in relatively small flares.…”

“…This may be a crucial physical factor in the wave generation and absorption or conversion (Hudson 2000). Studies of the configuration and temporal behaviour of the magnetic field in active regions Sudol and Harvey 2005;Kosovichev 2006b;Martínez-Oliveros et al 2007, 2008aMartínez Oliveros et al 2008b;Martínez Oliveros and Donea 2009;Hudson et al 2008) have attempted to explain the mystery of seismic events.…”

“…Further excess emission is distributed along the magnetic neutral line, approximately cospatial with the transient excess in white-light emission and the transient Doppler signature Donea and Lindsey (2005),Moradi et al (2006b). andMartínez-Oliveros et al (2008a) have drawn attention to the close correlation between the transient component of white-light emission, withLindsey and Donea (2008) specifically comparing egression-power and intensity-power variations in the 5-7-mHz band and seeing a remarkably close match.…”

Recent Developments in Local Helioseismology

“…We have touched on several areas of application. Although we have not discussed it here, there have also been a number of recent papers resulting from the holographic study of the seismic response of the solar interior to flares, which should improve our understanding of flare physics (Donea, 2006;Kosovichev, 2007;Martinez-Oliveros et al, 2007;Moradi et al, 2007;Zharkova and Zharkov, 2007).…”