A correlation between proto-planetary disc radii and sub-mm fluxes has been recently reported. In this letter, we show that the correlation is a sensitive probe of grain growth processes. Using models of grain growth and drift, we have shown in a companion paper that the observed disc radii trace where the dust grains are large enough to have a significant sub-mm opacity. We show that the observed correlation emerges naturally if the maximum grain size is set by radial drift, implying relatively low values of the viscous α parameter 0.001. In this case, the relation has an almost universal normalization, while if the grain size is set by fragmentation the flux at a given radius depends on the dust-to-gas ratio. We highlight two observational consequences of the fact that radial drift limits the grain size. The first is that the dust masses measured from the sub-mm could be overestimated by a factor of a few. The second is that the correlation should be present also at longer wavelengths (e.g. 3mm), with a normalization factor that scales as the square of the observing frequency as in the optically thick case.
On the millimetre continuum flux–radius correlation of proto-planetary discs / G.P. Rosotti, R.A. Booth, M. Tazzari, C. Clarke, G. Lodato, L. Testi. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. LETTERS. - ISSN 1745-3925. - 486:1(2019), pp. L63-L68.
|Titolo:||On the millimetre continuum flux–radius correlation of proto-planetary discs|
LODATO, GIUSEPPE (Penultimo)
|Parole Chiave:||accretion, accretion discs; planets and satellites: formation; protoplanetary discs; circumstellar matter; submillimetre: planetary systems|
|Settore Scientifico Disciplinare:||Settore FIS/05 - Astronomia e Astrofisica|
|Progetto:||Dust and gas in planet forming discs (DUSTBUSTER)|
|Data di pubblicazione:||2019|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1093/mnrasl/slz064|
|Appare nelle tipologie:||01 - Articolo su periodico|