Phase-resolved spectroscopy of the low-mass X-ray binary V801 Ara

We present phase-resolved optical spectra of the low mass X-ray binary system V801 Ara covering the full binary orbit of 3.8 hours obtained in 2014 with IMACS on the Magellan/Baade telescope at Las Campanas Observatory. The spectra contain strong emission features allowing us to map the system in velocity space. The radial velocity curves of the Bowen blend shows significantly stronger modulation at the orbital period than HAlpha as expected for the former originating on the secondary with the latter consistent with emission dominated by the disk. Our tomograms of HBeta and HAlpha clearly detect the accretion disk with HBeta emission extending to higher velocities than HAlpha which suggests emission from closer to the neutron star. The accretion disk does not appear centered on the center-of-mass of the neutron star as has been seen in several other X-ray binaries. This is often interpreted to imply disk eccentricity. None of our tomograms show a hot spot at the point where the accretion stream hits the disk which could imply a reduced accretion rate. However, there is enhanced emission further along the disk which implies gas stream interaction downstream of the hot spot.