MULTIWAVELENGTH OBSERVATIONS OF RV TAURI STARS .2. U-MONOCEROTIS

We present ultraviolet spectroscopy, and optical and infrared photomet ry, of the RV variable U Mon. The Mg II emission in this object seems to be chromospheric, with small variations in profile accompanying pul sational variations. The wavelengths of narrow absorption features ass ociated with the Mg II emission are essentially constant in time, and seem to be associated with cool circumstellar shell and a steady wind. We conclude that there is no evidence of binarity in U Mon, and that the long-term behaviour of the light curve is associated with R CrB-li ke ejection of clouds of absorbing material.