A Warped Dust Ring in the CQ Tau Disk

Résumé : The diversity of planetary orbital architectures calls for observational constraints on radial variations in disk-plane orientation, or warps, yet such variations in dust disks remain poorly characterized. CQ Tau is a promising target because its misaligned inner disk and candidate gas warp suggest a radially extended warp. We present the ALMA 1.3 mm dust continuum image reconstructed from the real part of the visibilities, extracting the centro-symmetric disk structure. At an effective spatial resolution of $0.052'' \times 0.042''$ ($7.8 \times 6.3$ au), the image reveals a bright main ring at radii of $\sim20$--$70$ au and an unresolved compact emission component tracing the inner disk around the central star. Ellipse fits centered on the stellar position to contours tracing the inner and outer edges of the ring reveal radial variations in position angles and inclinations. At the inner edge ($\sim21$--$26$ au), the position angle and inclination span $214^\circ$--$233^\circ$ and $23^\circ$--$39^\circ$, respectively, while they span $231^\circ$--$235^\circ$ and $33^\circ$--$36^\circ$ at the outer edge ($\sim58$--$67$ au). Whereas a coplanar ring toy model fails to reproduce such variations, a warped ring model with the local tilt decreasing from $\sim4^\circ$ at $r = 20$ au to $\sim1^\circ$ at 60 au reproduces them. The high-pass-filtered real-part image reveals a pair of opposed curved negative residuals. Similar features appear only in the warped ring model, further supporting the dust warp. These results establish CQ Tau as an example of a warped dust disk and an important laboratory for investigating the connection between three-dimensional disk geometry and planet formation.