Probing the presence of planets in transition discs' cavities via warps: the case of TW Hya

TL;DR

This paper explores how observing warped protoplanetary discs can reveal the presence and properties of planetary or substellar companions, using TW Hya as a case study and providing relations to interpret warp observations.

Contribution

It introduces a method linking disc warp amplitude to companion properties and applies it to specific transition discs, offering insights into planet detection via disc warps.

Findings

Warp detection requires massive planets (~10-14 M_J) and high disc viscosity (α ~ 0.15-0.25).

Application to TW Hya suggests a planetary companion could induce observable warps.

Model applied to LkCa 15 and T Cha confirms potential for warp-based planet detection.

Abstract

We are entering the era in which observations of protoplanetary discs properties can indirectly probe the presence of massive planets or low mass stellar companions interacting with the disc. In particular, the detection of warped discs can provide important clues to the properties of the star-disc system. In this paper we show how observations of warped discs can be used to infer the dynamical properties of the systems. We concentrate on circumbinary discs, where the mass of the secondary can be planetary. First, we provide some simple relations that link the amplitude of the warp in the linear regime to the parameters of the system. Secondly, we apply our method to the case of TW Hya, a transition disc for which a warp has been proposed based on spectroscopic observations. Assuming values for the disc and stellar parameters from observations, we conclude that, in order for a warp induced by a planetary companion to be detectable, the planet mass should be large ($M_{\rm p} \approx 10 - 14M_{\rm J}$) and the disc should be viscous ($\alpha \approx 0.15 - 0.25$). We also apply our model to LkCa 15 and T Cha, where a substellar companion has been detected within the central cavity of the transition discs.