Waves & Oscillations in the Solar Atmosphere: Heating and Magneto-Seismology Proceedings IAU Symposium No. 247, 2007 R. Erd´ elyi & C. A. Mendoza-Brice˜ no, eds. c  2008 International Astronomical Union doi:10.1017/S174392130801466X The nature of seismic sources associated with a proton-reach solar flare Valentyna V. Zharkova 1 and Serhij I. Zharkov 2 1 Department of Computing and Mathematics, University of Bradford, Bradford, UK, email: v.v.zharkova@brad.ac.uk 2 Department of Applied Mathematics, University of Sheffield, Sheffield, UK email: s.zharkov@sheffield.ac.uk Abstract. The momenta and start times measured from the TD diagrams in 3 seismic sources observed in the flare of 28 October 2003 are compared with those delivered to the photosphere by different kinds of high energy particles as well as by the hydrodynamic shocks caused by these particles. The energetic protons with energy power laws combined with quasi-thermal ones are shown to form hydrodynamic shocks deeply in a flaring atmosphere which deliver the required momentum to the photosphere within a measured timescale. The seismic waves observed in two sources associated with γ -rays can be explained by the momenta produced by hydrodynamic shocks caused by mixed proton beams and jets. The seismic wave in the source asociated with HXR only and delayed by 4 and 2 minutes from the first and second HXR bursts is likely to be associated with a hydrodynamic shock occurring from precipitation of a very powerful and hard electron beam possibly mixed with quasi-thermal lower energy protons. Keywords. Sun: activity, Sun: sunspots, Sun: interior, Sun: magnetic field, methods: data analysis, methods: statistical. 1. Introduction A comparison of the first observations of a solar quake (Kosovichev and Zharkova, 1998) with the theoretical model of a sesimic repsonse (Kosovichev and Zharkova, 1995) revealed that the momentum required to produce the observed seismic response (∼ 2· 10 22 g cm s -1 ) is one order of magnitude higher than those of ∼ 10 21 g cm s -1 observed from the plasma downflows in the MDI dopplergrams. Also the travel time of this shock to the photosphere is more than 2 minutes while the time, at which the helioseismic response started in TD diagrams, coincides very closely with the time of the hard X-ray impulse. Hence, there should be some additional sources that can deliver the required momentum to the solar photosphere within a very short timescale coinciding with the start time of a hard X-ray impulse. Recent observations reported helioseismic emission from the solar flares of 2003 Oc- tober 28 and 29 using the helioseismic holography technique (Donea and Lindsey, 2005; DL05 thereafter), with another 5 sources occurred in the active region NOAA 10486 with the seismic emission at frequencies from 3 mHz to 7 mHz, 4 of them in the flare 28 October 2003 (DL05). In order to establish a connection between high energy particles and the seismic source agents, in the present paper we study the velocities of vertical and horizontal displacements, or the ridges, associated with these seismic waves in the flare 28 October 2003, by applying the time-distance diagram technique and by deduc- ing the momenta required to cause the observed ridges. Then we can compare them with those delivered by high energy particles and hydrodynamic shocks occurring in the chromosphere in response to the particle injections. 59 https://www.cambridge.org/core/terms. https://doi.org/10.1017/S174392130801466X Downloaded from https://www.cambridge.org/core. IP address: 54.70.40.11, on 27 Jan 2019 at 04:45:17, subject to the Cambridge Core terms of use, available at