We introduce a new technique to determine the gas turbulence and surface density in bright disk rings, under the assumption that dust growth is limited by turbulent fragmentation at the ring center. We benchmark this prescription in HD 163296, showing that our measurements are consistent with available turbulence upper limits and agree with independent estimates of the gas surface density within a factor of 2. We combine our results with literature measurements of the dust surface density and grain size to determine the dust-to-gas ratio and Stokes number in the 67 and 100 au rings. Our estimates suggest that particle clumping is taking place under the effect of streaming instability (SI) in the 100 au ring. Even though in the presence of external isotropic turbulence this process might be hindered, we provide evidence that turbulence is nonisotropic in both rings and likely originates from mechanisms (such as ambipolar diffusion) that could ease particle clumping under SI. Finally, we determine the mass accretion rate under the assumption that the disk is in steady state and turbulence regulates angular momentum transport. Our results are in tension with spectroscopic measurements and suggest that other mechanisms might be responsible for accretion, in qualitative agreement with the detection of a magnetocentrifugal wind in this system. Applying our method to larger samples can be used to statistically assess if SI is a viable mechanism to form planetesimals in bright rings.

Observing Planetesimal Formation under Streaming Instability in the Rings of HD 163296 / F. Zagaria, C.J. Clarke, R.A. Booth, S. Facchini, G.P. Rosotti. - In: THE ASTROPHYSICAL JOURNAL LETTERS. - ISSN 2041-8205. - 959:2(2023 Dec 15), pp. L15.1-L15.10. [10.3847/2041-8213/ad0c54]

Observing Planetesimal Formation under Streaming Instability in the Rings of HD 163296

S. Facchini
Penultimo
;
G.P. Rosotti
Ultimo
2023

Abstract

We introduce a new technique to determine the gas turbulence and surface density in bright disk rings, under the assumption that dust growth is limited by turbulent fragmentation at the ring center. We benchmark this prescription in HD 163296, showing that our measurements are consistent with available turbulence upper limits and agree with independent estimates of the gas surface density within a factor of 2. We combine our results with literature measurements of the dust surface density and grain size to determine the dust-to-gas ratio and Stokes number in the 67 and 100 au rings. Our estimates suggest that particle clumping is taking place under the effect of streaming instability (SI) in the 100 au ring. Even though in the presence of external isotropic turbulence this process might be hindered, we provide evidence that turbulence is nonisotropic in both rings and likely originates from mechanisms (such as ambipolar diffusion) that could ease particle clumping under SI. Finally, we determine the mass accretion rate under the assumption that the disk is in steady state and turbulence regulates angular momentum transport. Our results are in tension with spectroscopic measurements and suggest that other mechanisms might be responsible for accretion, in qualitative agreement with the detection of a magnetocentrifugal wind in this system. Applying our method to larger samples can be used to statistically assess if SI is a viable mechanism to form planetesimals in bright rings.
Settore FIS/05 - Astronomia e Astrofisica
   Unveiling the infancy of planetary systems (UNVEIL)
   UNVEIL
   EUROPEAN COMMISSION
   101076613

   Rebuilding the foundations of planet formation: proto-planetary disc evolution (DiscEvol)
   DiscEvol
   EUROPEAN COMMISSION
   101039651

   Dust and gas in planet forming discs (DUSTBUSTER)
   DUSTBUSTER
   EUROPEAN COMMISSION
   H2020
   823823

   A new window into planet formation: disc kinematics
   FONDAZIONE CARIPLO
   ID Progetto 2022-1217
15-dic-2023
Article (author)
File in questo prodotto:
File Dimensione Formato  
Zagaria2023_b.pdf

accesso aperto

Tipologia: Publisher's version/PDF
Dimensione 682.94 kB
Formato Adobe PDF
682.94 kB Adobe PDF Visualizza/Apri
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/2434/1022548
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 1
  • ???jsp.display-item.citation.isi??? 1
social impact