CQ Tauri's dust ring reveals a changing warp

An ALMA image of CQ Tau shows a bright dust ring whose orientation changes with distance from the star. The ring extends roughly 20 to 70 astronomical units from CQ Tau. A model with a gradual warp fits the observed shape better than a flat ring, and the image contains additional patterns that support this interpretation.

Star system: CQ Tauri | Distance from the Sun: 487 light years

CQ Tau is surrounded by a broad ring of dust whose orientation changes with distance from the star. The bright ring spans about 20 to 70 astronomical units, while a compact, unresolved source of emission traces the inner disk. The changing orientation means the dust disk is warped rather than lying in one flat plane.

The ring was imaged with ALMA using light at a wavelength of 1.3 millimeters, which traces dust. The image has an effective resolution of about 7.8 by 6.3 astronomical units. Researchers measured the ring's shape by fitting ellipses to its inner and outer edges. An ellipse's position angle describes its direction on the sky, while its inclination describes how tilted it appears from our viewpoint.

The inner edge, at about 21 to 26 astronomical units, has position angles of 214° to 233° and inclinations of 23° to 39°. At the outer edge, about 58 to 67 astronomical units from the star, the ranges narrow to 231° to 235° and 33° to 36°. A flat-ring model does not match these changes. A warped model does, with its local tilt decreasing from about 4° at 20 astronomical units to about 1° at 60 astronomical units. A filtered image also shows two opposing curved patterns called negative residuals. Similar patterns appear in the warped model, providing further support for the disk's changing shape.

Key findings
The bright dust ring extends about 20 to 70 astronomical units from CQ Tau.
The ring's measured position angle and inclination vary between its inner and outer edges.
A warped-ring model fits the changes better than a flat, coplanar ring.
The model's local tilt declines from about 4° at 20 astronomical units to about 1° at 60 astronomical units.
Opposing curved patterns in the filtered image also support the presence of a dust warp.

Scientific study

A Warped Dust Ring in the CQ Tau Disk (external link)