Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): V721 CrA and BN CrA have wide and structured disks in polarised IR

TL;DR

This study uses near-infrared imaging to analyze the structure and properties of disks around two young stars in the CrA region, revealing their morphology, substructures, and evolutionary context.

Contribution

First detailed polarised IR imaging and modeling of disks around V721 CrA and BN CrA, highlighting their morphology, substructures, and evolutionary differences.

Findings

V721 CrA disk is thicker, smaller, and brighter with spiral arms.

BN CrA disk has a dark lane possibly indicating a dust gap or shadow.

Both disks are consistent with their respective evolutionary stages.

Abstract

We present near-infrared scattered-light observations of the disks around two stars of the Corona Australis star-forming region, V721 CrA, and BN CrA, obtained with VLT/SPHERE, in the H band, as part of the DESTINYS large programme. Our objective is to analyse the morphology of these disks, and highlight their main properties. We adopt an analytical axisymmetric disk model to fit the observations and perform a regression on key disk parameters, namely the dust mass, the height profile, and the inclination. We use RADMC-3D code to produce synthetic observations of the analytical models, with full polarised scattering treatment. Both stars show resolved and extended disks with substructures in the near-IR. The disk of V721 CrA is vertically thicker, radially smaller (120 au), and brighter than BN CrA (190 au). It also shows spiral arms in the inner regions. The disk of BN CrA shows a dark circular lane, which could be either an intrinsic dust gap or a self-cast shadow. Both disks are compatible with the evolutionary stage of their parent subgroup within the CrA region: V721 CrA belongs to the "on-cloud" part of CrA, which is dustier, denser and younger, whereas BN CrA is found on the outskirts of the older "off-cloud" group.