EMPIRICAL CONSTRAINTS ON TURBULENCE IN PROTOPLANETARY ACCRETION DISKS

By A. Hughes, D. Wilner, S. Andrews, C. Qi, M. Hogerheijde. 2010

145 citations recorded by the source corpus.

We present arcsecond-scale Submillimeter Array observations of the CO(3–2) line emission from the disks around the young stars HD 163296 and TW Hya at a spectral resolution of 44 m s−1. These observations probe below the ∼100 m s−1 turbulent linewidth inferred from lower-resolution observations, and allow us to place constraints on the turbulent linewidth in the disk atmospheres. We reproduce the observed CO(3–2) emission using two physical models of disk structure: (1) a power-law temperature distribution with a tapered density distribution following a simple functional form for an evolving accretion disk, and (2) the radiative transfer models developed by D'Alessio et al. that can reproduce the dust emission probed by the spectral energy distribution. Both types of models yield a low upper limit on the turbulent linewidth (Doppler b-parameter) in the TW Hya system (≲40 m s−1) and a tentative (3σ) detection of a ∼300 m s−1 turbulent linewidth in the upper layers of the HD 163296 disk. These correspond to roughly ⩽10% and 40% of the sound speed at size scales commensurate with the resolution of the data. The derived linewidths imply a turbulent viscosity coefficient, α, of order 0.01 and provide observational support for theoretical predictions of subsonic turbulence in protoplanetary accretion disks.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/718b9da3eb1500dedf49c3fbee69a39572694fd7

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Citations in the corpus

A NEW JEANS RESOLUTION CRITERION FOR (M)HD SIMULATIONS OF SELF-GRAVITATING GAS: APPLICATION TO MAGNETIC FIELD AMPLIFICATION BY GRAVITY-DRIVEN TURBULENCE (2011, background): “Observed turbulent Mach numbers in e.g., present-day proto-planetary disks are of the order of 0.1–0.5 (Hughes et al. 2011).”
A SPATIALLY RESOLVED VERTICAL TEMPERATURE GRADIENT IN THE HD 163296 DISK (2013, background): “…and spectrally and can be used to derive a dynamical mass of the young star (Guilloteau & Dutrey 1998; Simon et al. 2000), probe the structure of the disk (Dutrey et al. 2008; Panić et al. 2010), or detect non-thermal line broadening from turbulence (Hughes et al. 2011; Guilloteau et al. 2012).”
Gaps, Rings, and Non-Axisymmetric Structures in Protoplanetary Disks - From Simulations to ALMA Observations (2014, background): “It is assumed that the absolute value of this velocity component is on the order of 100 ms−1 (e.g., Dartois et al. 2003; Piétu et al. 2007; Hughes et al. 2011).”
ALMA Survey of Lupus Protoplanetary Disks. II. Gas Disk Radii (2018, unknown): “10−3 (Hughes et al. 2011; Flaherty et al. 2015; Teague et al. 2016).”
EXCLUSION OF COSMIC RAYS IN PROTOPLANETARY DISKS: STELLAR AND MAGNETIC EFFECTS (2013, background): “As one example, recent studies have sought to measure the degree of turbulence in protoplanetary disks by observing line broadening of strong gas emission lines (e.g., Hughes et al. 2011; Guilloteau et al. 2012).”
THE TW Hya DISK AT 870 μm: COMPARISON OF CO AND DUST RADIAL STRUCTURES (2011, methodology): “In a series of investigations focused almost exclusively on spectral line emission, Qi et al. (2004, 2006, 2008) and Hughes et al. (2011) relied on a slightly modified version of the physical structure model that was developed by Calvet et al. (2002) to match the TW Hya SED.”
Turbulence in the TW Hya Disk (2018, methodology): “We use a stellar mass of 0.7 M , identical to that used by T16, and slightly larger than the stellar mass assumed by Hughes et al. (2011) (0.6 M ).”
RESOLVED IMAGES OF LARGE CAVITIES IN PROTOPLANETARY TRANSITION DISKS (2011, background): “More direct approaches have focused on characterizing the anomalous viscosities, including attempts to measure the disk magnetic field structure (Hughes et al. 2009b) and turbulent velocities (Hughes et al. 2011).”
Resolved gas cavities in transitional disks inferred from CO isotopologs with ALMA (2015, background): “For reasonable planet masses (up to 10 Jupiter masses) that are consistent with the upper limits for companions mentioned above, this implies low viscosity values between α ∼ 10−3 and 10−4, much lower than found in the TW Hya and HD 163296 disks based on turbulent broadening (Hughes et al. 2011).”
Measuring turbulence in TW Hydrae with ALMA: methods and limitations (2016, methodology): “All previous measurements of vturb have relied on fitting a power-law model of a disk to the observations (Dartois et al. 2003; Piétu et al. 2007; Hughes et al. 2011; Guilloteau et al. 2012; Rosenfeld et al. 2012; Flaherty et al. 2015), so this allows for a direct comparison to previous results in…”
Complex organic molecules in protoplanetary disks (2013, background): “These latter facilities have enabled spatially-resolved mapping of very nearby objects including the archetypical protoplanetary disk, TW Hydrae, located at a distance of≈ 56 pc (Öberg et al. 2010, 2011; Hughes et al. 2011; Qi et al. 2011).”
A PARAMETRIC MODELING APPROACH TO MEASURING THE GAS MASSES OF CIRCUMSTELLAR DISKS (2013, background): “The turbulent component is known to be subsonic (Hughes et al. 2011), and we fix its value at ∆vturb = 0.01 km s −1.”
A Three-dimensional View of Turbulence: Constraints on Turbulent Motions in the HD 163296 Protoplanetary Disk Using DCO+ (2017, methodology): “Previous radio observations using the SMA and PdBI have found tentative evidence for turbulence (e.g., Hughes et al. 2011; Guilloteau et al. 2012).”
Volatile carbon locking and release in protoplanetary disks. A study of TW Hya and HD 100546 (2016, methodology): “The inclination is 7◦ ± 1◦ (Qi et al. 2004; Hughes et al. 2011; Andrews et al. 2012; Rosenfeld et al. 2012).”
WEAK TURBULENCE IN THE HD 163296 PROTOPLANETARY DISK REVEALED BY ALMA CO OBSERVATIONS (2015, methodology): “Detailed constraints on this structure help to mitigate one of the key degeneracies in earlier measurements of turbulence within this system (Hughes et al. 2011).”
Unveiling the gas-and-dust disk structure in HD 163296 using ALMA observations (2013, background): “Values similar to those estimated in other disks (e.g., Hughes et al. 2011) were considered.”
RINGED SUBSTRUCTURE AND A GAP AT 1 au IN THE NEAREST PROTOPLANETARY DISK (2016, methodology): “The current observational constraints on turbulent linewidths in the TW Hya disk (Hughes et al. 2011) are sensitive to much larger radii; it remains unclear if there is sufficient MHD tur- bulence in the 20–50 AU range to produce zonal flows consistent with the ALMA image.”
GLOBAL SIMULATIONS OF PROTOPLANETARY DISKS WITH OHMIC RESISTIVITY AND AMBIPOLAR DIFFUSION (2015, background): “More recent observations have indicated the presence of turbulence in the disks surrounding the young stars TW Hydrae and HD 163296, based on analysis of their molecular line emission (Hughes et al. 2011).”