Non-Keplerian spirals, a gas-pressure dust trap, and an eccentric gas cavity in the circumbinary disc around HD 142527. Issue 1 (19th April 2021)

• Record Type: Journal Article
• Authors: Garg, H; Pinte, C; Christiaens, V; Price, D J; Lazendic, J S; Boehler, Y; Casassus, S; Marino, S; Perez, S; Zuleta, A
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 504:Issue 1(2021)
• Page Start: 782
• Page End: 791
• Publication Date: 2021-04-19
• Subjects: circumstellar matter -- stars: individual: HD142527 -- submillimetre: planetary systems -- accretion, accretion discs; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab800
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present ALMA observations of the 12 CO, 13 CO, C 18 O J = 2-1 transitions and the 1.3 mm continuum emission for the circumbinary disc around HD 142527, at an angular resolution of ≈ 0${_{.}^{\prime\prime}}$ 3. We observe multiple spiral structures in intensity, velocity, and velocity dispersion for the 12 CO and 13 CO gas tracers. A newly detected 12 CO spiral originates from the dust horseshoe, and is rotating at super-Keplerian velocity or vertically ascending, whilst the interspiral gas is rotating at sub-Keplerian velocities. This new spiral possibly connects to a previously identified spiral, thus spanning >360°. A spatial offset of 30 au is observed between the 12 CO and 13 CO spirals, to which we hypothesize that the gas layers are propagating at different speeds (surfing) due to a non-zero vertical temperature gradient. Leveraging the varying optical depths between the CO isotopologues, we reconstruct temperature and column density maps of the outer disc. Gas surface density peaks at r ≈ 180 au, coincident with the peak of continuum emission. Here, the dust grains have a Stokes number of ≈ 1, confirming radial and azimuthal trapping in the horseshoe. We measure a cavity radius at half-maximum surface density of ≈ 100 au, and a cavity eccentricity between 0.3 and 0.45.