Based on the optical results we obtained for the stars within the error circle of 1WGA J1958.2+3232, we conclude that star B, a B0Ve spectral-type star, represents the very likely optical counterpart of 1WGA J1958.2+3232. We compared the optical findings with recent ASCA X-ray data obtained for this source (Israel et al. 1999), other similar X-ray sources (Haberl et al. 1998; Reig & Roche, 1999), and the current knowledge on accreting white dwarfs. We conclude that 1WGA J1958.2+3232 is a new likely faint Be/X-ray pulsar, probably belonging to a new subclass of Be X-ray binary systems with long periods, persistent, low luminosities X-ray emission, and small flux variations. If the accreting white dwarf interpretation proves instead correct, than 1WGA J1958.2+3232 would be the first unambiguous example of a Be/white dwarf binary system.
© European Southern Observatory (ESO) 1999
Online publication: April 12, 1999