UV observations of LB 3193 and LB 3116 : two hot post-AGB object in the galactic halo ?

Abstract

LB 3193 and LB 3116 have visual spectra indicating that they are B2-B5 supergiants situated at large distances from the galactic plane. UV observations of both objects show that they are metal deficient stars, whose energy distributions match their adopted atmospheric parameters. Further investigation of mass luminosity relationships of various evolutionary phases suggest that they are more likely to be low mass stars of about 0.5-1.0 solar mass in a transitionary stage between the asymptotic giant branch and planetary nebulae phases. In turn this means that they are much closer to the galactic plane than first thought and hence are among the hottest post-AGB stars yet discovered.