Multiwavelength optical observations of chromospherically active binary systems III. High resolution echelle spectra from CaIIH& K to CaIIIRT

This is the third paper of a series aimed at studying the chromosphere of a ctive binary systems using the information provided for several optical spe ctroscopic features. High resolution echelle spectra including all the opti cal chromospheric activity indicators from the Ca II H & K to Ca II IRT lin es are analysed here for 16 systems. The chromospheric contribution in thes e lines has been determined using the spectral subtraction technique. Very broad wings have been found in the subtracted H alpha profilp of the very a ctive star HU Vir. These profiles are well matched using a two-component Ga ussian fit; (narrow and broad) ard the broad component carl be interpreted as arising from microflaring. Red-shifted absorption features in the H alph a line have been detected in several systems and excess emission in the blu e wing of FG UMa was also detected. These features indicate that several dy namical processes, or a combination of them, may be involved. Using: the E- H alpha/E-H beta ratio as: a diagnostic we have detected prominence-like ex tended material viewed off the limb in many stars of the sample, and promin ences viewed against the disk at some orbital phases in the dwarfs OU Gem a nd BF Lyn, The He I D-3 line has been detected as an absorption feature in mainly all the giants of the sample. Total filling-in of the He I D-3, prob ably due to microflaring activity, is observed in HU Vir. Self-absorption w ith red asymmetry is detected in the Ca II H & K lines of the giants 12 Cam : FG UMa and BM CVn. All the stars analysed show clear filled-in Ca II IRT lines or even notable emission reversal. The small values of the E-8542/E-8 498 ratio we have found indicate Ca II IRT emission arises from plage-like regions. Orbital phase modulation of the chromospheric emission has been de tected in some systems, in the case of HU Vir evidence of an active longitu de area has been found.