ALMA observations of Elias 2-24: a protoplanetary disk with multiple gaps in the Ophiuchus Molecular Cloud

TL;DR

This study uses ALMA observations to identify multiple gaps in the Elias 2-24 protoplanetary disk, suggesting potential planet formation at different radii near snow-lines, with detailed modeling of disk structure and planet masses.

Contribution

First detailed ALMA imaging of Elias 2-24 revealing multiple gaps and constraining their origins and associated planet masses through radiative transfer modeling.

Findings

Three concentric gaps at 20, 52, and 87 au identified.

Estimated planet masses range from 0.02 to 8 Jupiter masses.

Gaps are near snow-lines of CO and N2, indicating possible planet formation zones.

Abstract

We present ALMA 1.3 mm continuum observations at 0.2" (25 au) resolution of Elias 2-24, one of the largest and brightest protoplanetary disks in the Ophiuchus Molecular Cloud, and report the presence of three partially resolved concentric gaps located at ~20, 52, and 87 au from the star. We perform radiative transfer modeling of the disk to constrain its surface density and temperature radial profile and place the disk structure in the context of mechanisms capable of forming narrow gaps such as condensation fronts and dynamical clearing by actively forming planets. In particular, we estimate the disk temperature at the locations of the gaps to be 23, 15, and 12 K (at 20, 52, and 87 au respectively), very close to the expected snow-lines of CO (23-28 K) and N2 (12-15 K). Similarly, by assuming that the widths of the gaps correspond to 4-8 x the Hill radii of forming planets (as suggested by numerical simulations), we estimate planet masses in the range of 0.2-1.5 M_Jup, 1.0-8.0 M_Jup, and 0.02-0.15 M_Jup for the inner, middle, and outer gap, respectively. Given the surface density profile of the disk, the amount of "missing mass" at the location of each one of these gaps (between 4 and 20 M_Jup) is more than sufficient to account for the formation of such planets.