Spectral study of a spray-like eruptive prominence

The 2D Hα spectral data of the spray-like eruptive prominence (EP) of March 5, 1991 are obtained and analyzed quantitatively by means of the `multi-cloud model' (MCM) method. Four physical quantities (i.e. the column number density of hydrogen atoms at the second level along the line-of-sight direction, N2, the excitation temperature Tex, the line-of-sight velocity V// and the micro-turbulence velocity Vt) and their 2D fields are derived. Results show that the EP may be divided into two parts, i.e. a main body (including the middle and the base of the EP) and a top part; the former is denser and hotter with a high macro-velocity and a nearly empty core, the latter thiner and cooler with a relatively higher micro-turbulence velocity. The 2D distributions of N2, Tex, V// and Vt exhibit the properties of inhomogeneity and asymmetry of the EP. The values of N2 and Tex of the main body are all much greater than those of the top part of the prominence, N2 ranges between 5 and 35×1012 cm−2 and Tex ranges from 5 to 20×103 K, with the one of the top part lower than that of the main body. Two “mound” structures with higher temperatures and higher densities locate in two (upper and lower) regions of the main body. The blue-shift velocity in the EP predominates absolutely, the V// varies from 8.0 to −110.0 km s−1 on an average, with the higher velocity appearing in the main body. The Vt at the top part seems greater than that in the main body, with an averaged value being 30–40 km s−1. The emission measure EM, electron density ne and pressure Pe in the EP are also estimated.