Orbital and sub-orbital period determination of the candidate high-mass X-ray binary HD 3191

Abstract

Aims. The final aim of this paper is to expand the sparse group of X-ray binaries with gamma-ray counterparts as laboratories to study high-energy processes under physical conditions that periodically repeat. Methods. A follow-up of a candidate system has been carried out. We applied both photometric and spectroscopic techniques in the optical domain together with a period analysis using the phase dispersion minimisation and CLEAN methods. A tentative period search was also conducted in the gamma-ray domain. Results. Our main result is having established the binary nature of the optical star and X-ray emitter HD 3191 towards the Fermi gamma-ray source 4FGL J0035.8+6131, the last one proposed to be associated with a blazar of an unknown type. An orbital period close to 16 d is reported for HD 3191 together with a likely rotation, or pulsation, period of about 0.6 d. Although no convincing evidence for the orbital cycle has been found in the Fermi light curve up to now, the confirmed presence of a high-mass X-ray binary towards 4FGL J0035.8+6131 now strengthens the need for caution about its true nature.

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

“…The second counterpart candidate to the flaring gammaray source J0035+6131 is the optically bright and X-ray star HD 3191 (V = 8:6, spectral type B1 IV:nn). Follow up photometric study of HD 3191 by Martí et al (2021) confirmed the binary nature of this star with an estimated orbital period of 16.09 ± 0.01 d. Modeling of the light curve tentatively suggested it to be an X-ray binary system close to Roche lobe overflow. Their additional detection of a 4686 Å emission line from HeII was interpreted as an accretion disk signature as it is an uncommon spectral feature for a single B-type star.…”

“…The log of observation dates is given in the first columns of Table 1. To compute the orbital phase, a binary period of 16.09 ± 0.01 d and zero phase set at HJD 2458750.14 are assumed according to the photometric elements in Martí et al (2021). This phase origin is expected to coincide with the inferior conjunction of the optical star.…”