The SPHERE view of the Chamaeleon I star-forming region

TL;DR

This study used VLT/SPHERE and archival data to observe 20 systems in the Chamaeleon I star-forming region, revealing disk structures, asymmetries, and the impact of stellar companions on circumstellar material.

Contribution

First detailed scattered light observations of multiple systems in Cha I, linking disk features with system age, dust mass, and stellar multiplicity.

Findings

Detected resolved scattered light in 13 systems, including first detailed descriptions for several.

Found a rare extended multiple-ringed disk around SZ Cha.

Observed a brightness asymmetry in HD 97048 suggesting disk misalignment.

Abstract

We used VLT/SPHERE to observe 20 systems in the Cha I cloud in polarized scattered light in the near-infrared. We combined the scattered light observations with existing literature data on stellar properties and with archival ALMA continuum data to study trends with system age and dust mass. We also connected resolved near-infrared observations with the spectral energy distributions of the systems. In 13 of the 20 systems included in this study we detected resolved scattered light signals from circumstellar dust. For the CR Cha, CT Cha, CV Cha, SY Cha, SZ Cha, and VZ Cha systems we present the first detailed descriptions of the disks in scattered light. The observations found typically smooth or faint disks, often with little substructure, with the notable exceptions of SZ Cha, which shows an extended multiple-ringed disk, and WW Cha, which shows interaction with the cloud environment. New high S/N K- band observations of the HD 97048 system in our survey reveal a significant brightness asymmetry that may point to disk misalignment and subsequent shadowing of outer disk regions, possibly related to the suggested planet candidate in the disk. We resolve for the first time the stellar binary in the CS Cha system. Multiple wavelength observations of the disk around CS Cha have revealed that the system contains small, compact dust grains that may be strongly settled, consistent with numerical studies of circumbinary disks. We find in our sample that there is a strong anti-correlation between the presence of a (close) stellar companion and the detection of circumstellar material with five of our seven nondetections located in binary systems.