A new planet candidate detected in a dust gap of the disc around HD 163296 through localised kinematic signatures. An observational validation of the Discminer

TL;DR

This paper presents the detection of two potential planets in the disc around HD 163296 through localised kinematic signatures using the DISCMINER framework, revealing their properties and associated gas structures.

Contribution

The study introduces a new application of DISCMINER for identifying localized planetary signatures and characterizes gas and dust structures in the disc.

Findings

Detection of two candidate planets at 94 au and 261 au with specific azimuths.

Identification of gas gaps at 38, 88, and 136 au matching dust and kinematic features.

Observation of azimuthal asymmetries in line widths linked to planetary turbulence.

Abstract

We report the robust detection of coherent, localised deviations from Keplerian rotation possibly associated with the presence of two giant planets embedded in the disc around HD 163296. The analysis is performed using the DISCMINER channel-map modelling framework on $^{12}$CO $J=2-1$ DSHARP data. Not only orbital radius, but also azimuth of the planets are retrieved by our technique. One of the candidate planets, detected at $R=94\pm6$ au, $\phi=50\pm3^\circ$ (P94), is near the centre of one of the gaps in dust continuum emission, and is consistent with a planet mass of 1 $\rm M_{\rm Jup}$. The other planet, located at $R=261\pm4$ au, $\phi=57\pm1^\circ$ (P261), is in the region where a velocity kink was previously observed in $^{12}$CO channel maps. Also, we provide a simultaneous description of the height and temperature of the upper and lower emitting surfaces of the disc, and propose the line width as a solid observable to track gas substructure. Using azimuthally averaged line width profiles we detect gas gaps at $R=38$ au, $R=88$ au, and $R=136$ au, closely matching the location of their dust and kinematical counterparts. Furthermore, we observe strong azimuthal asymmetries in line widths around the gas gap at $R=88$ au, possibly linked to turbulent motions driven by the P94 planet. Our results confirm that the DISCMINER is capable of finding localised, otherwise unseen velocity perturbations thanks to its robust statistical framework, but also that it is well suited for studies of the gas properties and vertical structure of protoplanetary discs.