Discovery of a Debris Disk Around TWA 20

TL;DR

This paper reports the discovery and detailed imaging of a debris disk around the low-mass star TWA 20 using JWST, demonstrating the telescope's capability to detect faint disks around dim stars.

Contribution

First high-resolution scattered light imaging of a debris disk around an M dwarf star using JWST, with detailed modeling of disk morphology and orientation.

Findings

Disk radius of approximately 65 AU

Inclination of about 70 degrees

Detection of a nebulous, non-axisymmetric structure

Abstract

We report the discovery of a debris disk surrounding the M3 star, TWA 20, revealed by JWST coronagraphic observations using the Near-infrared Camera (NIRCam). With reference-star differential imaging (RDI), we resolve the disk in scattered light in the F200W filter at a high signal-to-noise ratio and in the F444W filter at a low signal-to-noise ratio. The disk morphology and orientation are characterized via a forward modeling approach, where we determine a radius of 64.7-6.5+6.2 AU and an inclination of 70.1-3.3+2.5 deg. Utilizing our forward model, we improve the fidelity of the debris disk image using model-constrained RDI (MCRDI). The newly discovered disk is one of only 6 disks detected in scattered light that orbit M dwarf stars; it is the third largest of the 6 resolved M dwarf disks and orbits the third faintest host star. The detection of this disk exemplifies the sensitivity of JWST to debris disks around low-luminosity host stars, which have historically been difficult to detect because these disks are cool and dim. We identify a nebulous structure that cannot be explained by an axisymmetric disk. A search for companions in the TWA 20 system yields no candidates.