A novel observational test of momentum balance in a solar flare

The paper reports measurements of upflowing and downflowing plasma during the impulsive phase of a solar flare, based on Solar Maximum Mission X-ray spectra and Sacramento Peak Observatory Hα imaging spectra. Observations of the blue asymmetry of x-ray spectral lines, indicative of upflow, in the coronal Ca XIX line were obtained. Simultaneous observations of the red asymmetry of Hα line profiles, indicative of downflow, in bright Hα kernals were also carried out. It was found that, to within observational uncertainty, the momentum transported by the upflowing X-ray plasma was the same as that of the downflowing Hα material. (UK)