The Lyman α and Lyman β lines in solar coronal streamers

We use the plasma parameters derived from a new global 2.5D three fluid model of the solar wind to compute the Lyman-α and Lyman-β line profiles. The emergent hydrogen radiation is calculated by solving the statistical equilibrium equations for a 10 level hydrogen atom + continuum along a one-dimensional line of sight. We do not make any assumption about the formation mechanisms of the lines. We study the effect of Doppler dimming. We find that the width of the Lyman-β line more accurately reflects the plasma temperature than that of the Lyman-α line. Thus inferred temperatures from Lymanα observations should be considered as lower limits for the plasma temperature. We also present calculations of the relative contribution of resonant scattering and collisional excitation in the Lyman line intensities.