1999MNRAS.302...48M

The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope has been used to observe α Tau (K5 III). The resulting spectra contain many sharp fluorescent lines. Most of these have been identified as lines of Fe ii, Ca ii and H₂, radiatively excited by H Lyα. The chromospheric model developed in an accompanying paper has been used to calculate the fluxes in these lines. The Ca ii lines have been modelled with a full radiative transfer calculation, but the Fe ii and H₂ systems are more complex and, for these, a simpler calculation has been made. Overall, the trend in the Fe ii line fluxes provides evidence for a multicomponent model of the atmosphere, a chromosphere with intrusions of hotter material or vice versa. The hotter material could be in shocks propagating through the chromosphere. Comparisons of the observed and calculated fluxes of individual lines of Fe ii show that some atomic data need to be improved. The analysis of the H₂ lines is restricted by a lack of suitable molecular data. The two observed Ca ii lines are reproduced to within a factor of 2.