The binary central star of the bipolar pre-planetary nebula IRAS 08005-2356 (V510 Pup)

Abstract: Current models predict that binary interactions are a major ingredient for the formation of bipolar planetary nebulae (PNe) and pre-planetary nebulae (PPNe). Despite years of radial velocity (RV) monitoring, the paucity of known binaries amongst the latter systems is insufficient to examine this relationship in detail. In this paper, we report on the discovery of a long period (P=2654$\pm$124 d) binary at the centre of the Galactic bipolar PPN, IRAS 08005-2356 (V510 Pup) determined from long-term spectroscopic and near-infrared time series data. The spectroscopic orbit is fit with an eccentricity of 0.36$\pm$0.05 that is similar to other long period post-AGB binaries. Time resolved H$\alpha$ profiles reveal high-velocity outflows (jets) with de-projected velocities up to 231${-27}^{+31}$ km s$^{-1}$ seen at phases when the luminous primary is behind the jet. The outflow traced by H$\alpha$ is likely produced via accretion onto a main sequence companion for which we calculate a mass of 0.63$\pm$0.13 M$\odot$. This discovery is one of the first cases of a confirmed binary PPN and demonstrates the importance of high-resolution spectroscopic monitoring surveys on large telescopes in revealing binarity among these systems.