Circumbinary, not transitional: On the spiral arms, cavity, shadows, fast radial flows, streamers and horseshoe in the HD142527 disc

TL;DR

This study uses 3D hydrodynamical models to demonstrate that the complex features of the HD142527 protoplanetary disc, including spirals, shadows, and dust structures, are caused by its binary companion rather than a transitional disc scenario.

Contribution

The paper provides a comprehensive hydrodynamical model showing that the observed disc features are due to binary interaction, challenging the transitional disc interpretation.

Findings

Binary companion explains all observed features

Inclined, eccentric orbit reproduces spiral and shadow positions

Dust simulations match observed dust concentration patterns

Abstract

We present 3D hydrodynamical models of the HD142527 protoplanetary disc, a bright and well studied disc that shows spirals and shadows in scattered light around a 100 au gas cavity, a large horseshoe dust structure in mm continuum emission, together with mysterious fast radial flows and streamers seen in gas kinematics. By considering several possible orbits consistent with the observed arc, we show that all of the main observational features can be explained by one mechanism - the interaction between the disc and the observed binary companion. We find that the spirals, shadows and horseshoe are only produced in the correct position angles by a companion on an inclined and eccentric orbit approaching periastron - the 'red' family from Lacour et al. (2016). Dust-gas simulations show radial and azimuthal concentration of dust around the cavity, consistent with the observed horseshoe. The success of this model in the HD142527 disc suggests other mm-bright transition discs showing cavities, spirals and dust asymmetries may also be explained by the interaction with central companions.