Extragalactic symbiotic systems. II. Hubble Space Telescope observations of S 63 and Linsay 358.

We present ultraviolet spectra of two symbiotic systems in the Magellanic Clouds obtained with the Faint Object Spectrograph onboard the refurbished Hubble Space Telescope. Because of the known distances to the LMC and SMC, and because of the high sensitivity of HST, accurate luminosities and radiation temperatures of the hot radiation source in S 63 and Linsay 358 can be derived. In addition, we determine relative CNO abundances of the nebular gas in these interacting binaries. For S 63 we find the nebular chemistry intermediate between carbon and normal stars. This might be due to a mixing of wind material from the carbon companion and mass lost from the hot radiation source. Support for this interpretation comes from the observed Nvλ1240 profile of S 63 which has a P Cygni character. For Linsay 358the CNO abundance ratios are compatible with those of a K-giant.