GG Tau A: gas properties and dynamics from the cavity to the outer disk

Abstract

We used new ALMA ${}^{13}$CO and C${}^{18}$O(3-2) observations obtained at high angular resolution ($\sim$0.2") together with previous CO(3-2) and (6-5) ALMA data and continuum maps at 1.3 and 0.8 mm in order to determine the gas properties (temperature, density, and kinematics) in the cavity and to a lesser extent in the outer disk of GG Tau A, the prototype of a young triple T Tauri star that is surrounded by a massive and extended Keplerian outer disk. By deprojecting, we studied the radial and azimuthal gas distribution and its kinematics. We also applied a new method to improve the deconvolution of the CO data and in particular better quantify the emission from gas inside the cavity. We perform local and nonlocal thermodynamic equilibrium studies in order to determine the excitation conditions and relevant physical parameters inside the ring and in the central cavity. Residual emission after removing a smooth-disk model indicates unresolved structures at our angular resolution, probably in the form of irregular rings or spirals. The outer disk is cold, with a temperature $<20$ K beyond 250 au that drops quickly (r${}^{-1}$). The kinematics of the gas inside the cavity reveals infall motions at about 10% of the Keplerian speed. We derive the amount of gas in the cavity, and find that the brightest clumps, which contain about 10% of this mass, have kinetic temperatures 40$-$80 K, CO column densities of a few 10${}^{17}$ cm${}^{-2}$, and H${}_2$ densities around 10${}^7$ cm${}^{-3}$. Although the gas in the cavity is only a small fraction of the disk mass, the mass accretion rate throughout the cavity is comparable to or higher than the stellar accretion rate. It is accordingly sufficient to sustain the circumstellar disks on a long timescale.

arXiv comment18 pages, 14 figures

References in corpus (25)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• Spectral Energy Distributions of T Tauri Stars With Passive Circumstellar Disks
• The Transiting Circumbinary Planets Kepler-34 and Kepler-35
• Probing the structure of protoplanetary disks: a comparative study of DM Tau, LkCa 15 and MWC 480
• A Spectroscopic Survey of Subarcsecond Binaries in the Taurus-Auriga Dark Cloud with the Hubble Space Telescope
• Extrasolar planets in stellar multiple systems
• Oxygen depletion in dense molecular clouds: a clue to a low O2 abundance?
• Circumbinary disk evolution
• Chemistry in Protoplanetary Disks: the gas-phase CO/H2 ratio and the Carbon reservoir
• Empirical Temperature Measurement in Protoplanetary Disks
• Spiral Arms, Infall, and Misalignment of the Circumbinary Disk from the Circumstellar Disks in the Protostellar Binary System L1551 NE
• First detection of H${}_2$S in a protoplanetary disk. The dense GG Tau A ring
• Active-Region Tilt Angles: Magnetic Versus White-Light Determinations of Joy's Law
• Angular Momentum Exchange by Gravitational Torques and Infall in the Circumbinary Disk of the Protostellar System L1551 NE
• A Spitzer Five-Band Analysis of the Jupiter-Sized Planet TrES-1
• GG Tau: the fifth element
• The Orbit of GG Tau A
• High resolution imaging of the GG Tau system at 267 GHz
• Dynamics of Circumstellar Disks III: The case of GG Tau A
• Mapping CO Gas in the GG Tauri A Triple System with 50 AU Spatial Resolution
• Circumbinary Ring, Circumstellar disks and accretion in the binary system UY Aurigae
• Testing dust trapping in the circumbinary disk around GG Tau A
• AGN disks and black holes on the weighting scales
• GG Tau A: Dark shadows on the ringworld

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• Accretion rates in hierarchical triple systems with discs
• Precession and polar alignment of accretion discs in triple (or multiple) stellar systems
• Polar circumtriple planets and disks can only form close to a triple star
• An unbiased NOEMA 2.6 to 4 mm survey of the GG Tau ring: First detection of CCS in a protoplanetary disk
• Orbital dynamics in the GG Tau A system: investigating its enigmatic disc
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