Several mechanisms have been proposed to explain the transient seismic emission, i.e. “sunquakes,” from some solar flares. Some theories associate high-energy electrons and/or white-light emission with sunquakes. High-energy charged particles and their subsequent heating of the photosphere and/or chromosphere could induce acoustic waves in the solar interior. We carried out a correlative study of solar flares with emission in hard X-rays, enhanced continuum emission at 6173 Å, and transient seismic emission. We selected those flares observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) with a considerable flux above 50 keV between 1 January 2010 and 26 June 2014. We then used data from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory to search for excess visible-continuum emission and new sunquakes not previously reported. We found a total of 18 sunquakes out of 75 flares investigated. All of the sunquakes were associated with an enhancement of the visible continuum during the flare. Finally, we calculated a coefficient of correlation for a set of dichotomic variables related to these observations. We found a strong correlation between two of the standard helioseismic detection techniques, and between sunquakes and visible-continuum enhancements. We discuss the phenomenological connectivity between these physical quantities and the observational difficulties of detecting seismic signals and excess continuum radiation.
Bibliographical noteFunding Information:
We thank Sandra M. Buitrago-Casas for her valuable comments during the writing of this article. The Berkeley group was supported by NASA under contract NAS-5-98033 for RHESSI. This article was written based on fruitful discussions at the Leverhulme Flare Seismology Workshop held at the Mullard Space Science Laboratory (MSSL), 9 – 12 September 2013, supported by the Leverhulme project “Probing the Sun Inside and Out”. The authors who attended the workshop thank the Leverhulme hosts for their hospitality during the visit to MSSL. Data are provided by courtesy of NASA/SDO and the HMI science team.
© 2015, Springer Science+Business Media Dordrecht.
- Flares, white-light flares