The Anatomy of an Unusual Edge-on Protoplanetary Disk. I. Dust Settling in a Cold Disk

Abstract As the earliest stage of planet formation, massive, optically thick, and gas-rich protoplanetary disks provide key insights into physics star formation. When viewed edge-on, high-resolution images offer a unique opportunity to study both radial vertical structures these relate this settling, drift, grain growth, changes in midplane temperatures. In work, we present multi-epoch Hubble Space Telescope Keck scattered light images, an Atacama Large Millimeter/submillimeter Array 1.3 mm continuum map for remarkably flat edge-on disk SSTC2DJ163131.2–242627, young solar-type ρ Ophiuchus. We model 0.8 μ m separate Markov Chain Monte Carlo (MCMC) runs investigate geometry dust properties using MCFOST radiative transfer code. light, are sensitive smaller grains surface layers disk, while submillimeter observations probe larger closer midplane. An MCMC run combining data sets covariance-based log-likelihood estimation was marginally successful, implying insufficient complexity our model. The is well characterized by flared with exponentially tapered outer edge nearly though some degree settling required reproduce vertically thin profile lack apparent flaring. A colder than expected midplane, evidence residual substructures all point more complex density be probed future, higher-resolution observations.