Spectroscopic Observations of Some S-Type Symbiotic Stars

Abstract

Observations of a group of S-type symbiotic stars are presented : Hen 828, Hen 905, Hen 1103, Hen 1213, KX TrA (Cn 1-2), AE Ara (PC 18), AS 255, AS 270, AS 289, Y CrA, AS 304, AS 316, AS 327, and CD [43¡14304. The observations were made in three di erent epochs of observation : 1987, 1991, and 1995, except for Y CrA, which was observed in 1990. Several parameters are obtained for each object : spectral types of the late components; distances derived from these spectral types ; interstellar reddening as determined from the Balmer decrement, considering optical depth e ects ; electron temperatures and densities ; helium abundances, also determined considering optical depth e ects ; and characteristics of the hot components. It has been found that Hen 828 and Hen 1103 were possibly having an outburst in 1991; the same could be true for AS 270 in 1995 and CD [43¡14304 in 1991. Another interesting object is Hen 905, which is surrounded by a nebulosity that could be a ring, reaching a distance of about 2@, with emission mainly in Ha and O VI j6825.