A kinematic excess in the annular gap and gas depleted cavity in the disc around HD 169142

H. Garg , C. Pinte (1) , I. Hammond , R. Teague , T. Hilder , D. J. Price , J. Calcino , V. Christiaens , P. P. Poblete

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble

We present ALMA band 6 images of the ¹²CO, ¹³CO and C¹⁸O J=2-1 line emissions for the circumstellar disc around HD 169142, at ~8 au spatial resolution. We resolve a central gas depleted cavity, along with two independent near-symmetric ring-like structures in line emission: a well-defined inner gas ring [~25 au] and a second relatively fainter and diffuse outer gas ring [~65 au]. We identify a localised super-Keplerian feature or vertical flow with a magnitude of ~75ms^-1 in the ¹²CO map. This feature has the shape of an arc that spans azimuthally across a PA range of -60^○ to 45^○ and radially in between the B1[26au] and B2[59au] dust rings. Through reconstruction of the gas surface density profile, we find that the magnitude of the background perturbations by the pressure support and self-gravity terms are not significant enough to account for the kinematic excess. If of planetary origin, the relative depletion in the gas-density profile would suggest a 1 M_J planet. In contrast, the central cavity displays relatively smooth kinematics, suggesting either a low mass companion and/or a binary orbit with a minimal vertical velocity component.

Keywords: accretion discs; circumstellar matter; submillimetre: planetary systems; stars: individual: HD169142; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics

Domains: Sciences of the Universe [physics]

H. Garg, C. Pinte, I. Hammond, R. Teague, T. Hilder, et al.. A kinematic excess in the annular gap and gas depleted cavity in the disc around HD 169142. Monthly Notices of the Royal Astronomical Society, 2022, ⟨10.1093/mnras/stac3039⟩. ⟨insu-03860272⟩