Very peculiar wind from BD+53 2790, the optical counterpart to 4U 2206+54

BD+53 2790, an O9.5Vp star, is the optical counterpart to the HMXRB
 4U 2206+54. This system was classified initially as a BeX, but
 observational evidence soon stressed the need to revise this classification.
 The permanent asymmetry in the H-alpha line profiles (in contrast with
 the cyclic variations shown by Be stars), the variations in the profile
 of this line in time scales of hours (while time scales from weeks to
 months are expected in Be stars), and the lack of correlation between
 IR observables and H-alpha line parameters, strongly suggest that,
 while BD+53 2790 contains a circunstellar disc, it is not like the o
 ne present in Be stars. Furthermore, there is evidence of overabundance
 of He in BD+53 2790. Together with the presence of an anomalous wind,
 found through UV spectroscopy, the possibility to link this star with
 the group of He rich stars is open. We will discuss the work done with
 IUE data from BD+53 2790 and the unexpected finding of a slow and dense
 wind, very rare for an O9.5V star.

0806.4103v1.pdf155.98 KB
P. Blay (U. Valencia), M. Ribó (U. Barcelona), I. Negueruela (U. Alicante)
Sunday, 1 Jun 2008