Hints of the photometric period in radial velocity data of the X-ray binary HD 3191 with the Joan Oró telescope

Abstract

We focus our attention on the newly proposed X-ray binary system HD 3191 whose nature still lacks dynamical confirmation and accurate orbital parameters. The positional agreement of this object with a flaring gamma-ray source was the original motivation of this work, although the present chances of association are reduced. A long-term spectroscopic monitoring of HD3191 was conducted using the 1-m class, robotic, Joan Oró telescope at the Observatori Astronòmic del Montsec facilities, located in the pre-Pyrenees mountains 140 km away from Barcelona. The Doppler measurements suggest an agreement with the previously reported 16.09 d photometric period, as expected. We also present a very preliminary radial velocity curve based on a circular orbit solution that hints to a low velocity amplitude. Nevertheless, the instrumental limitations of our data render necessary to carry out improved spectroscopic observations to better discriminate among the nature of the compact companion.