Optical Line profile variability of the B1+neutron star binary system LS I+65 010 = 2S 0114+650

Koenigsberger, Gloria; Canalizo, Gabriela; Arrieta, Anabel; Richer, Michael G.; Georgiev, Leonid

Optical Line profile variability of the B1+neutron star binary system LS I+65 010 = 2S 0114+650

Authors

Koenigsberger, Gloria

Description

We present high resolution spectroscopic observations of the massive X-ray binary system LS I+65 010=2S 0114+650 in the optical wavelength region. A correlation between equivalent width and radial velocity of photospheric absorption lines is found. The systemic velocity, inferred from the weaker lines is v_helio = -31 +/- 5 km s^-1, which, if attributed solely to the Galactic rotation curve, implies that LS I+65 010 lies within 3 kpc from the Sun. The ISM Na I D lines display 2 resolved high velocity components at v_helio = -70, -48 km s^-1, possibly associated with gas surrounding the binary system, in addition to the -24, -8 km s^-1 ISM features due to the Orion and the Perseus arm regions. Strong photospheric line profile variability is present on a night to night timescale, with He I 5875 A displaying an additional blue-shifted absorption in some of the spectra, similar to what is observed in the optical counterpart of Vela X-1. A connection between the extended blue wing and X-ray maximum is suggested. Short timescale variations in line profiles are detected on only two nights, but the evidence that these variations occur on the 2.78 hour X-ray flaring period is marginal.
33 pages, including 13 eps figures. Uses rmaa.cls (included). To appear in RevMexAA