The Structure of the DoAr 25 Circumstellar Disk

TL;DR

This study uses high-resolution submillimeter observations and modeling to analyze the structure and evolution of the circumstellar disk around DoAr 25, revealing insights into its density profile, mass, and potential for planet formation.

Contribution

It provides the first detailed modeling of DoAr 25's disk structure using submillimeter data, exploring different density profiles and dust properties to understand disk evolution.

Findings

Disk has a shallow surface density profile (p=0.34)

Total disk mass is approximately 0.10 solar masses

Inner disk densities may be too low for planet formation

Abstract

We present high spatial resolution (< 0.3" = 40$ AU) Submillimeter Array observations of the 865 micron continuum emission from the circumstellar disk around the young star DoAr 25. Despite its bright millimeter emission, this source exhibits only a comparatively small infrared excess and low accretion rate, suggesting that the material and structural properties of the inner disk may be in an advanced state of evolution. A simple model of the physical conditions in the disk is derived from the submillimeter visibilities and the complete spectral energy distribution using a Monte Carlo radiative transfer code. For the standard assumption of a homogeneous grain size distribution at all disk radii, the results indicate a shallow surface density profile, $\Sigma \propto r^{-p}$ with p = 0.34, significantly less steep than a steady-state accretion disk (p = 1) or the often adopted minimum mass solar nebula (p = 1.5). Even though the total mass of material is large (M_d = 0.10 M_sun), the densities inferred in the inner disk for such a model may be too low to facilitate any mode of planet formation. However, alternative models with steeper density gradients (p = 1) can explain the observations equally well if substantial grain growth in the planet formation region (r < 40 AU) has occurred. We discuss these data in the context of such models with dust properties that vary with radius and highlight their implications for understanding disk evolution and the early stages of planet formation.