First Sunquake of Solar Cycle 24 Observed by Solar Dynamics Observatory

TL;DR

This paper reports the first observed sunquake of Solar Cycle 24 caused by an X2.2-class flare, utilizing high-resolution data from SDO's HMI instrument to analyze seismic waves and flare impact on the Sun's surface.

Contribution

It provides the first detailed observation of a sunquake during Solar Cycle 24, highlighting the seismic response to a major solar flare using high-resolution, near-real-time helioseismic data.

Findings

Sunquake observed near a complex sunspot region

Seismic waves formed a compact wavepacket traveling through the solar interior

Flare impact caused rapid variations in HMI observables

Abstract

The X2.2-class solar flare of February 15, 2011, produced a powerful `sunquake' event, representing a seismic response to the flare impact. The impulsively excited seismic waves formed a compact wavepacket traveling through the solar interior and appeared on the surface as expanding wave ripples. The Helioseismic and Magnetic Imager (HMI), instrument on SDO, observes variations of intensity, magnetic field and plasma velocity (Dopplergrams) on the surface of Sun almost uninterruptedly with high resolution (0.5 arcsec/pixel) and high cadence (45 sec). The flare impact on the solar surface was observed in the form of compact and rapid variations of the HMI observables (Doppler velocity, line-of-sight magnetic field and continuum intensity). These variations, caused by the impact of high-energy particles in the photosphere, formed a typical two-ribbon flare structure. The sunquake can be easily seen in the raw Dopplergram differences without any special data processing. The source of this quake was located near the outer boundary of a very complicated complicated sunspot region, NOAA 1158, in a sunspot penumbra and at the penumbra boundary. This caused an interesting plasma dynamics in the impact region. I present some preliminary results of analysis of the near-real-time data from HMI, and discuss properties of the sunquake and the flare impact sources.