Multiwavelength analysis for interferometric (sub-)mm observations of protoplanetary disks - Radial constraints on the dust properties and the disk structure

By M. Tazzari, L. Testi, Barbara Ercolano, A. Natta, Andrea Isella, C. Chandler, L. Pérez, S. Andrews, D. Wilner, L. Ricci and 13 more. 2015

136 citations recorded by the source corpus.

Context. The growth of dust grains from sub-mu m to mm and cm sizes is the first step towards the formation of planetesimals. Theoretical models of grain growth predict that dust properties change as a function of disk radius, mass, age, and other physical conditions. High angular resolution observations at several (sub-)mm wavelengths constitute the ideal tool with which to directly probe the bulk of dust grains and to investigate the radial distribution of their properties. Aims. We lay down the methodology for a multiwavelength analysis of (sub-) mm and cm continuum interferometric observations to self-consistently constrain the disk structure and the radial variation of the dust properties. The computational architecture is massively parallel and highly modular. Methods. The analysis is based on the simultaneous fit in the uv-plane of observations at several wavelengths with a model for the disk thermal emission and for the dust opacity. The observed flux density at the different wavelengths is fitted by posing constraints on the disk structure and on the radial variation of the grain size distribution. Results. We apply the analysis to observations of three protoplanetary disks (AS 209, FT Tau, DR Tau) for which a combination of spatially resolved observations in the range similar to 0.88 mm to similar to 10 mm is available from SMA, CARMA, and VLA. In these disks we find evidence of a decrease in the maximum dust grain size, a(max), with radius. We derive large a(max) values up to 1 cm in the inner disk 15 AU <= R <= 30 AU and smaller grains with a(max) similar to 1 mm in the outer disk (R greater than or similar to 80 AU). Our analysis of the AS 209 protoplanetary disk confirms previous literature results showing a(max) decreasing with radius. Conclusions. Theoretical studies of planetary formation through grain growth are plagued by the lack of direct information on the radial distribution of the dust grain size. In this paper we develop a multiwavelength analysis that will allow this missing quantity to be constrained for statistically relevant samples of disks and to investigate possible correlations with disk or stellar parameters.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/dae48366b7dcc6469070080fb0b854aaaabdd7ce

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Citations in the corpus

Chemical enrichment of giant planets and discs due to pebble drift (2017, background): “…of protoplanetary discs show that there is a reservoir of such pebbles from which the embryos can accrete (Wilner et al. 2005; Rodmann et al. 2006; Lommen et al. 2007; Pérez et al. 2012; Tazzari et al. 2016), making pebble accretion an attractive model for the formation of giant planets.”
The Disk Substructures at High Angular Resolution Project (DSHARP). I. Motivation, Sample, Calibration, and Overview (2018, background): “Resolved variations in the continuum spectrum shape have been interpreted as radial gradients in the particle size distributions (larger solids closer to the star; Isella et al. 2010; Guilloteau et al. 2011; Pérez et al. 2012, 2015; Menu et al. 2014; Tazzari et al. 2016; Tripathi et al. 2018).”
The Disk Substructures at High Angular Resolution Project (DSHARP). II. Characteristics of Annular Substructures (2018, background): “Multiwavelength observations are desirable for constraining dust optical depths (e.g., Pérez et al. 2012; Tazzari et al. 2016), but a rough estimate can still be obtained from the single-wavelength DSHARP observations by approximating the midplane temperature profile with the simplified expression…”
A millimeter Continuum Size–Luminosity Relationship for Protoplanetary Disks (2017, background): “While Piétu et al. (2014) appear to have tentatively found a similar correlation at ∼230 GHz, we know empirically that the spatial extents of continuum emission from disks tend to increase with the observing frequency (e.g., Pérez et al. 2012, 2015; Menu et al. 2014; Tazzari et al. 2016).”
Molecules with ALMA at Planet-forming Scales (MAPS). I. Program Overview and Highlights (2021, background): “In addition, observations at mm and cm wavelengths shows clear evidence for both grain growth and pebble-size dependent grain drift (Pérez et al. 2012; Tazzari et al. 2016).”
Evidence for the formation of comet 67P/Churyumov-Gerasimenko through gravitational collapse of a bound clump of pebbles (2017, background): “…increasing distance to the central star: at 10 au, the pebble sizes are around 25 mm, whereas at 50 au, the maximum dust radii reach only 1-5 mm. Tazzari et al. (2016) analysed that the maximum size falls off with distance to the central star following a power law with exponent ∼ -1.5, whereas…”
Compact Disks in a High-resolution ALMA Survey of Dust Structures in the Taurus Molecular Cloud (2019, background): “…wavelength is expected to be more compact as a consequence of dust grain growth and radial drift (e.g., Pérez et al. 2012, 2015, Menu et al. 2014, Tazzari et al. 2016), when the gas pressure profile is smooth in the outer disk, a factor of 2 difference at such close wavelengths (grain sizes) is…”
One Solution to the Mass Budget Problem for Planet Formation: Optically Thick Disks with Dust Scattering (2019, background): “Previous spatially resolved α measurements have shown that α decreases towards the inner disk (Pérez et al. 2012, 2015; Tazzari et al. 2016; Carrasco-González et al. 2016).”
A STEEPER THAN LINEAR DISK MASS–STELLAR MASS SCALING RELATION (2016, background): “Because an S/N on the continuum 30 is needed to properly estimate dust disk sizes (Tazzari et al. 2016), deeper ALMA observations are needed to pin down whether and how the disk size scales with stellar mass.”
ALMA Survey of Lupus Protoplanetary Disks. II. Gas Disk Radii (2018, background): “…had the same grain population as full disks before the inner disk clearing, and also that βd increases with radius (e.g., Guilloteau et al. 2011; Tazzari et al. 2016), then disks with large inner cavities should lack large grains and therefore appear to have higher αmm values compared to full…”
ALMA continuum observations of the protoplanetary disk AS 209. Evidence of multiple gaps opened by a single planet (2017, methodology): “In this paper we fix smax = 2000 µm in agreement with the multi-frequency continuum analysis of AS 209 by Tazzari et al. (2016).”