Evidence of a past disc-disc encounter: HV and DO Tau

Theory and observations suggest that star formation occurs hierarchically due to the fragmentation of giant molecular clouds. In this case we would expect substructure and enhanced stellar multiplicity in the primordial cluster. This substructure is expected to decay quickly in most environments, however historic stellar encounters might leave imprints in a protoplanetary disc (PPD) population. In a low density environment such as Taurus, tidal tails from violent star-disc or disc-disc encounters might be preserved over time-scales sufficient to be observed. In this work, we investigate the possibility that just such an event occured between HV Tau C (itself a component of a triple system) and DO Tau $\sim 0.1$ Myr ago, as evidenced by an apparent `bridge' structure evident in the $160$ $\mu$m emission. By modelling the encounter using smoothed particle hydrodynamics (SPH) we reproduce the main features of the observed extended structure (`V'-shaped emission pointing west of HV Tau and a tail-like structure extending east of DO Tau). We suggest that HV Tau and DO Tau formed together in a quadruple system on a scale of $\sim 5000$ au ($0.025$ pc).