JWST imaging of edge-on protoplanetary disks. I. Fully vertically mixed 10$\mu$m grains in the outer regions of a 1000 au disk

TL;DR

This study uses JWST imaging to analyze the structure and dust properties of an edge-on protoplanetary disk, revealing that grains up to 10 micrometers are fully coupled with gas and suggesting possible disk wind activity.

Contribution

First JWST 2-21 micron images of a protoplanetary disk are presented, showing minimal morphological change across wavelengths and providing new insights into dust grain coupling and disk dynamics.

Findings

Dust surface layers exhibit nearly gray opacity law.

Grains up to ~10 micrometers are fully coupled to gas.

Detection of an X-shaped feature possibly related to disk wind.

Abstract

Scattered light imaging of protoplanetary disks provides key insights on the geometry and dust properties in the disk surface. Here we present JWST 2--21\,$\mu$m images of a 1000\,au-radius edge-on protoplanetary disk surrounding an 0.4\,$M_\odot$ young star in Taurus, 2MASS\,J04202144+2813491. These observations represent the longest wavelengths at which a protoplanetary disk is spatially resolved in scattered light. We combine these observations with HST optical images and ALMA continuum and CO mapping. We find that the changes in the scattered light disk morphology are remarkably small across a factor of 30 in wavelength, indicating that dust in the disk surface layers is characterized by an almost gray opacity law. Using radiative transfer models, we conclude that grains up to $\gtrsim10\,\mu$m in size are fully coupled to the gas in this system, whereas grains $\gtrsim100\,\mu$m are strongly settled towards the midplane. Further analyses of these observations, and similar ones of other edge-on disks, will provide strong empirical constraints on disk dynamics and evolution and grain growth models. In addition, the 7.7 and 12.\,$\mu$m JWST images reveal an X-shaped feature located above the warm molecular layer traced by CO line emission. The highest elevations at which this feature is detectable roughly match the maximal extent of the disk in visible wavelength scattered light as well as of an unusual kinematic signature in CO. We propose that these phenomena could be related to a disk wind entraining small dust grains.