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Stellar multiplicity affects the correlation between protoplanetary disc masses and accretion rates: binaries explain high accretors in Upper Sco

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journal contribution
posted on 10.05.2022, 05:06 by Francesco Zagaria, Cathie J Clarke, Giovanni P Rosotti, Carlo F Manara

In recent years, a correlation between mass accretion rates onto new-born stars and their protoplanetary disc masses was detected in nearby young star-forming regions. Although such a correlation can be interpreted as due to viscous-diffusion processes in the disc, highly accreting sources with low disc masses in more evolved regions remain puzzling. In this paper, we hypothesize that the presence of a stellar companion truncating the disc can explain these outliers. First, we searched the literature for information on stellar multiplicity in Lupus, Chamaeleon I, and Upper Sco, finding that roughly 20 per cent of the discs involved in the correlation are in binaries or higher order multiple stellar systems. We prove with high statistical significance that at any disc mass these sources have systematically higher accretion rates than those in single-stars, with the bulk of the binary population being clustered around Mdisc/ ˙Macc≈0.1Myr⁠. We then run coupled gas and dust one-dimensional evolutionary models of tidally truncated discs to be compared with the data. We find that these models are able to reproduce well most of the population of observed discs in Lupus and Upper Sco, even though the unknown eccentricity of each binary prevents an object by object comparison. In the latter region, the agreement improves if the grain coagulation efficiency is reduced, as may be expected in discs around close binaries. Finally, we mention that thermal winds and sub-structures can be important in explaining few outlying sources.

History

Citation

Monthly Notices of the Royal Astronomical Society, Volume 512, Issue 3, May 2022, Pages 3538–3550, https://doi.org/10.1093/mnras/stac621

Author affiliation

School of Physics and Astronomy, University of Leicester

Published in

Monthly Notices of the Royal Astronomical Society

Volume

512

Issue

3

Pagination

3538 - 3550

Publisher

Oxford University Press (OUP)

issn

0035-8711

eissn

1365-2966

Acceptance date

03/03/2022

Copyright date

2022

Available date

10/05/2022

Language

en