Effects of Ringed Structures and Dust Size Growth on Millimeter Observations of Protoplanetary Disks

Abstract

The growth of solids from sub-micron to millimeter and centimeter sizes is the early step toward the formation of planets inside protoplanetary disks (PPDs). However, such processes and their potential impact on the later stages of solid growth are still poorly understood. In this work, we test the hypothesis that most disks contain at least one ringed structure with a relative small radius. We have carried out a large family of 1D two-fluid (gas+dust) hydrodynamical simulations by evolving the gas and dust motion self-consistently while allowing dust size to evolve via coagulation and fragmentation. We investigate the joint effects of ringed structures and dust size growth on the overall sub-millimeter and millimeter (mm) flux and spectral index of PPDs. Ringed structures slow down the dust radial drift and speed up the dust growth. In particular, we find that those unresolved disks with a high fragmentation velocity ($\sim 10\mathrm{m}{\mathrm{s}}^{-1}$) and a high dust surface density ($\sim 10\mathrm{g}\mathrm{c}{\mathrm{m}}^{-2}$ in the ring) can have mm spectral indices as low as $\sim 2.0$, consistent with mm observations of faint disks in nearby star forming regions. Furthermore, disks with more than one ringed structure can potentially reproduce brighter disks with spectral indices lower than $\sim 2.5$. Future multi-wavelength high-resolution observations of these low spectral index sources can be used to test the existence of the ringed structures in the unresolved disks and differentiate the effects of dust size growth from optical depth.

18 pages, accepted for publication in ApJ

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Cited by in corpus (4)

• Including Dust Coagulation in Hydrodynamic Models of Protoplanetary Disks: Dust Evolution in the Vicinity of a Jupiter-mass Planet
• The Preservation of Super Earths and the Emergence of Gas Giants after Their Progenitor Cores have Entered the Pebble Isolation Phase
• On the Dust Signatures Induced by Eccentric Super-Earths in Protoplanetary Disks
• Ring Morphology with Dust Coagulation in Protoplanetary Disks