Transition disks: 4 candidates for ongoing giant planet formation in Ophiuchus (Research Note)

TL;DR

This study models the structure of four candidate planet-forming transition disks in Ophiuchus, revealing evacuated cavities likely carved by embedded giant planets, and emphasizes the need for further high-resolution observations.

Contribution

It provides detailed radiative transfer modeling of four transition disks, constraining their cavity sizes and dust properties, supporting their candidacy for ongoing giant planet formation.

Findings

Disks have evacuated cavities of 2-8 AU.

Models suggest mild grain growth and dust settling.

Further high-resolution imaging is needed for better constraints.

Abstract

A large set of Spitzer-selected transitional disks in the Ophiuchus molecular cloud was recently examined by Cieza et al (2010), and 4 of the targets were identified as (giant) planet-forming candidates based on the morphology of their Spectral Energy Distributions (SEDs), the apparent lack of stellar companions, and evidence for accretion. Here we characterize the structures of these disks modeling their optical, infrared and (sub)millimeter SEDs. We use the Monte Carlo radiative transfer package RADMC to construct a parametric model of the dust distribution in a flared disk with an inner cavity and calculate the temperature structure consistent with the density profile, in thermal equilibrium with the irradiating star. For each object, we conducted a Bayesian exploration of the parameter space generating Monte Carlo Markov Chains (MCMC) that allow the identification of the best fit parameters and to constrain their range of statistical confidence. Our calculations point to the presence of evacuated cavities with radii ~2-8 AU, consistent with having been carved by embedded giant planets. We found parameter values consistent with those previously given in the literature, indicating a mild degree of grain growth and dust settling, which deserves to be investigated with further modeling and follow up observations. Resolved images with (sub)millimeter interferometers are required to break some of the degeneracies of the models and better constrain the physical properties of these fascinating disks.