The HD 98800 quadruple pre-main sequence system - Towards full orbital characterisation using long-baseline infrared interferometry

HD 98800 is a young (∼10 Myr old) and nearby (∼45 pc) quadruple system, composed of two spectroscopic binaries orbiting around each other (AaAb and BaBb), with a gas-rich disk in polar configuration around BaBb. While the orbital parameters of BaBb and AB are relatively well constrained, this is not the case for AaAb. A full characterisation of this quadruple system can provide insights on the formation of such a complex system. We use multi-epoch interferometric observations with the Very Large Telescope Interferometer PIONIER and radial velocities. The PIONIER observations provide relative astrometric positions and flux ratios for both AaAa and BaBb subsystems. Combining the astrometric points with radial velocity measurements, we determine the orbital parameters of both subsystems. In this poster we will present the refined orbital solution of BaBb, and for the first time, the full orbital solution of AaAb. We confirmed the polar configuration of the circumbinary disk around BaBb. From our solutions, we also inferred the dynamical masses of AaAb (MAa=0.93 ± 0.09 and MAb=0.29 ± 0.02 M). We will discuss the long term stability, the possible formation scenarios and the future work towards full orbital characterisation of this young quadruple system.