Ground based and IUE spectral observations of AU Mon.

Abstract

Results of ground-based and IUE spectral observations of the close binary AU Monocerotis made in January 1979, are reported. The ground-based observations made in the spectral regions 3600-4500 and 4900-7200 A show radial velocities and H-alpha emission suggestive of radial outflow from a subgiant component at high velocities, and from a B5 primary surrounded by a gaseous ring at lower velocities. IUE images, taken at phases 0.5 and 0.66, exhibit only absorption lines of varying widths and a large range in excitation, which suggests the presence of a source of nonthermal energy in the system, probably arising from the dissipation of shock waves in the mass outflow.