IUE observations of the late type star RW Hya (gM2 + pec) have been obtained. Analysis of the intense UV continuum observed between 1100 and 2000 A suggests that this object is a binary system in which the secondary is identified as the central star of a planetary nebula with Teff 105 K. The ultraviolet spectrum is characterized by semiforbidden and allowed transition lines, of which the C IV (1548 A, 1550 A) doublet is particularly strong. A general absence of strong forbidden line emission suggests that the compact nebula in which both primary and secondary stars are embedded has particularly high densities of ~10^8-10^9 cm^-3 . Tidal interaction rather than steady state mass flow from the M giant is suggested as a means to form a nebula with the characteristic densities inferred from our UV line analysis. RW Hya is suggested as a possible source of soft X-ray emission if material is accreting onto the surface of the secondary. A general discussion concerning the ionic abundances of various atomic ions present is given.
Kafatos, M., Michalitsianos, A.G., Hobbs, R.W. (1980) IUE Observations of RW Hydrae (gM2 + pec), Astrophysical Journal, 240: 114-124. doi: 10.1086/158213