ALMA Survey of Lupus Protoplanetary Disks II: Gas Disk Radii
Authors
Ansdell, M
Williams, JP
Trapman, L
Terwisga, SE van
Facchini, S
Manara, CF
Marel, N van der
Miotello, A
Hogerheijde, M
Guidi, G
Testi, L
Dishoeck, EF van
Publication Date
2018-05-20Journal Title
The Astrophysical Journal
ISSN
1538-4357
Publisher
IOP Publishing
Volume
859
Issue
1
Number
21
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Ansdell, M., Williams, J., Trapman, L., Terwisga, S. v., Facchini, S., Manara, C., Marel, N. v. d., et al. (2018). ALMA Survey of Lupus Protoplanetary Disks II: Gas Disk Radii. The Astrophysical Journal, 859 (1. 21) https://doi.org/10.3847/1538-4357/aab890
Abstract
We present ALMA Band 6 observations of a complete sample of protoplanetary disks in the young (1-3 Myr) Lupus star-forming region, covering the 1.33 mm continuum and the 12CO, 13CO, and C18O J=2-1 lines. The spatial resolution is 0.25 arcsec with a medium 3-sigma continuum sensitivity of 0.30 mJy, corresponding to M_dust ~ 0.2 M_earth. We apply "Keplerian masking" to enhance the signal-to-noise ratios of our 12CO zero-moment maps, enabling measurements of gas disk radii for 22 Lupus disks; we find that gas disks are universally larger than mm dust disks by a factor of two on average, likely due to a combination of the optically thick gas emission as well as the growth and inward drift of the dust. Using the gas disk radii, we calculate the dimensionless viscosity parameter, alpha_visc, finding a broad distribution and no correlations with other disk or stellar parameters, suggesting that viscous processes have not yet established quasi-steady states in Lupus disks. By combining our 1.33 mm continuum fluxes with our previous 890 micron continuum observations, we also calculate the mm spectral index, alpha_mm, for 70 Lupus disks; we find an anti-correlation between alpha_mm and mm flux for low-mass disks (M_dust < 5), followed by a flattening as disks approach alpha_mm = 2, which could indicate faster grain growth in higher-mass disks, but may also reflect their larger optically thick components. In sum, this work demonstrates the continuous stream of new insights into disk evolution and planet formation that can be gleaned from unbiased ALMA disk surveys.
Sponsorship
European Research Council (341137)
Embargo Lift Date
2100-01-01
Identifiers
External DOI: https://doi.org/10.3847/1538-4357/aab890
This record's URL: https://www.repository.cam.ac.uk/handle/1810/276673
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