The HMXRB system BD+37° 1160/4U 0515+38 Original Research Article

We present new optical data on BD+37° 1160, the optical counterpart of the X-ray source 1H0521+373 (=4U0515+38). The analysis of the stellar spectrum confirms that it is a very high mass object that probably experienced in the past several shell emission episodes. From the present optical data we find clear evidence of a new shell being ejected by the star. The hard spectrum of the X-ray source points to the presence of a compact companion. The similarity of the optical spectrum of BD+37° 1160 in the X-ray active phase with that of X Per strongly suggests that BD+37° 1160 is a BeXRB with a collapsed companion on a very wide orbit.