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. [10.1093/mnrasl/slz064]

On the millimetre continuum flux–radius correlation of proto-planetary discs

G.P. Rosotti
;
G. Lodato
Penultimo
;
2019

Abstract

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.
accretion, accretion discs; planets and satellites: formation; protoplanetary discs; circumstellar matter; submillimetre: planetary systems
Settore FIS/05 - Astronomia e Astrofisica
Dust and gas in planet forming discs (DUSTBUSTER)
Article (author)
File in questo prodotto:
File Dimensione Formato  
Rosottietal19a.pdf

accesso aperto

Tipologia: Pre-print (manoscritto inviato all'editore)
Dimensione 853.87 kB
Formato Adobe PDF
853.87 kB Adobe PDF Visualizza/Apri
slz064.pdf

accesso riservato

Tipologia: Publisher's version/PDF
Dimensione 445.56 kB
Formato Adobe PDF
445.56 kB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/645081
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 27
  • ???jsp.display-item.citation.isi??? 24
social impact