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On the secular evolution of the ratio between gas and dust radii in protoplanetary discs

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journal contribution
posted on 06.09.2021, 14:04 by Claudia Toci, Giovanni Rosotti, Giuseppe Lodato, Leonardo Testi, Leon Trapman
A key problem in protoplanetary disc evolution is understanding the efficiency of dust radial drift. This process makes the observed dust disc sizes shrink on relatively short time-scales, implying that discs started much larger than what we see now. In this paper, we use an independent constraint, the gas radius (as probed by CO rotational emission), to test disc evolution models. In particular, we consider the ratio between the dust and gas radius, RCO/Rdust. We model the time evolution of protoplanetary discs under the influence of viscous evolution, grain growth, and radial drift. Then, using the radiative transfer code RADMC with approximate chemistry, we compute the dust and gas radii of the models and investigate how RCO/Rdust evolves. Our main finding is that, for a broad range of values of disc mass, initial radius, and viscosity, RCO/Rdust becomes large (>5) after only a short time (<1 Myr) due to radial drift. This is at odds with measurements in young star-forming regions such as Lupus, which find much smaller values, implying that dust radial drift is too efficient in these models. Substructures, commonly invoked to stop radial drift in large, bright discs, must then be present, although currently unresolved, in most discs.

History

Citation

Monthly Notices of the Royal Astronomical Society, Volume 507, Issue 1, October 2021, Pages 818–833, https://doi.org/10.1093/mnras/stab2112

Author affiliation

Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Volume

507

Issue

1

Pagination

818 - 833

Publisher

Oxford University Press (OUP)

issn

0035-8711

eissn

1365-2966

Acceptance date

20/07/2021

Copyright date

2021

Available date

06/09/2021

Language

en