A quantitative analysis of the surge of March 19, 1989

Abstract

A large surge event appearing in AR 5395 was observed at the Yunnan Observatory on March 19, 1989. Hα spectral profiles of the event are interpreted by using a two-cloud model and the contours of three parameters: excitation temperature, T exc, microturbulent velocity, V t ,and column density of hydrogen atoms at the second level, N 0,2, are obtained, respectively. The question about the unique feature of the solution obtained by the fitting method is also discussed. The results show that the surge is composed of some conglomerated materials with higher temperature and density; the mass ejection is probably intermittent. Neither T exc nor N 0,2 vary with the height over the solar limb but decrease from the center to the periphery of the surge. V t varies from 10 to 30 km s-1 and decreases with height. Some other important parameters, such as electron density, n e ,and electron pressure, P e ,etc., have also been estimated. In the surge, with N 0,2 about 2.0 × 1012 cm-2 and T exc about 8500 K on average, we obtained n e = 1.80 × 1010 cm-3 and P e = 0.023 dyn cm-2. The energy variations of the surge during the ascending phase are estimated.