Spectro-polarimetric observations and non-LTE modeling of Ellerman bombs

摘要

Ellerman bombs are bright emission features observed in the wings of H alpha, usually in the vicinity of magnetic concentrations. Here we show that they can also be detected in the Ca II infrared triplet lines, which are easier to interpret and therefore allow for more detailed diagnostics. We present full Stokes observations of the 849.8 and 854.2 nm lines acquired with the new spectro-polarimeter SPINOR. The data show no significant linear polarization at the level of 3 x 10(-4). The circular polarization profiles exhibit measureable signals with a very intricate pattern of peaks. A non-LTE analysis of the spectral profiles emerging from these features reveals the presence of strong downflows (similar to 10 {km s(-1)) in a hot layer between the upper photosphere and the lower chromosphere.