Rings of C2H in the Molecular Disks Orbiting TW Hya and V4046 Sgr

TL;DR

This study images C2H emission in the disks around TW Hya and V4046 Sgr, revealing ring-like structures likely caused by irradiation effects, and compares their inner hole radii.

Contribution

First high-resolution imaging of C2H in these disks, showing ring morphology and differences in inner hole sizes, advancing understanding of disk chemistry and irradiation effects.

Findings

C2H emission forms rings in both disks

Inner hole radius is larger in V4046 Sgr (~70 AU) than in TW Hya (~45 AU)

C2H likely traces irradiation of disk surface layers

Abstract

We have used the Submillimeter Array to image, at ~1" resolution, C2H(3-2) emission from the molecule-rich circumstellar disks orbiting the nearby, classical T Tauri star systems TW Hya and V4046 Sgr. The SMA imaging reveals that the C2H emission exhibits a ring-like morphology within each disk, the inner hole radius of the C2H ring within the V4046 Sgr disk (~70 AU) is somewhat larger than than of its counterpart within the TW Hya disk (~45 AU). We suggest that, in each case, the C2H emission likely traces irradiation of the tenuous surface layers of the outer disks by high-energy photons from the central stars.