Multiwavelength analysis of a well observed flare from SMM

Abstract

We describe and analyse observations of an M1.4 flare which began at 17: 00 UT on 12 November, 1980. Ground based Hα and magnetogram data have been combined with EUV, soft and hard X-ray observations made with instruments on-board the Solar Maximum Mission (SMM) satellite. The preflare phase was marked by a gradual brightening of the flare site in Ov and the disappearance of an Hα filament. Filament ejecta were seen in Ov moving southward at a speed of about 60 km s−1, before the impulsive phase. The flare loop footpoints brightened in Hα and the Caxix resonance line broadened dramatically 2 min before the impulsive phase. Non-thermal hard X-ray emission was detected from the loop footpoints during the impulsive phase while during the same period blue-shifts corresponding to upflows of 200–250 km s−1 were seen in Ca xix. Evidence was found for energy deposition in both the chromosphere and corona at a number of stages during the flare. We consider two widely studied mechanisms for the production of the high temperature soft X-ray flare plasma in the corona, i.e. chromospheric evaporation, and a model in which the heating and transfer of material occurs between flux tubes during reconnection.