Gas and dust in an edge-on protoplanetary disk: An in-depth multiwavelength analysis
Abstract
Circumstellar disks associated with pre-main sequence stars are active sites of planet formation. Among the processes expected to play an important role in the first Myrs of the evolution of the disk are the growth of increasingly larger solid bodies and the decoupling of dust grains from the gas. The latter process, induced by drag forces, leads to the vertical settling and radial migration of millimeter-sized grains. Quantitative comparisons of the distribution of the gas and (grain size-dependent) dust components are necessary to test hydrodynamical and dust growth models. High-resolution observations of edge-on protoplanetary disks offer a unique opportunity to study the vertical structure of disks as their upper layers can be unambiguously disentangled from the midplane. Here we present optical and near-infrared high-resolution scattered light images (from HST and Keck) and sub-millimeter dust continuum and CO maps (from ALMA) of an unusually flat edge-on disk associated with a low-accretion Sun-like star in the Ophiuchus star-forming region. Using this rich dataset, we performed radiative transfer modeling of dust observations and tomographic reconstruction of the gas temperature in the disk. Our results allow us to compare the gas scale height inferred from the scattered light images to the temperatures measured directly in the CO-emitting layers. We also find strong evidence for vertical settling of the millimeter-sized dust, although our prescription for settling does not simultaneously fit well both scattered light images and continuum emission maps. Additionally, the gas emission extends significantly (60% larger) beyond the outer radius at which scattered light and continuum emission are detected. Indeed, while the disk midplane is cold enough for CO to freeze out outside of about 100au, this outer region is characterized mostly by isothermal CO emission throughout the entire vertical extent of the disk, possibly caused by external illumination.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23530809D