First detection of c-C3H2 in a circumstellar disk

TL;DR

This study reports the first detection of c-C3H2 in a circumstellar disk around HD 163296, revealing a ring structure that could serve as a probe for radiation penetration in such disks.

Contribution

First detection of c-C3H2 in a circumstellar disk, with spatial distribution analysis using ALMA data, highlighting its potential as a radiation probe.

Findings

c-C3H2 detected in a ring from 30 to 165 AU

Column density estimated at 1e12-1e13 cm-2

Potential as a probe of radiation in disks

Abstract

We report the first detection of c-C3H2 in a circumstellar disk. The c-C3H2 J=6-5 line (217.882 GHz) is detected and imaged through Atacama Large Millimeter Array (ALMA) Science Verification observations toward the disk around the Herbig Ae star HD 163296 at 0.8" resolution. The emission is consistent with that arising from a Keplerian rotating disk. Two additional c-C3H2 transitions are also tentatively detected, bolstering the identification of this species, but with insufficient signal-to-noise ratio to constrain the spatial distribution. Using a previously developed model for the physical structure of this disk, we fit a radial power-law distribution model to the c-C3H2 6-5 emission and find that c-C3H2 is present in a ring structure from an inner radius of about 30 AU to an outer radius of about 165 AU. The column density is estimated to be 1e12-1e13 cm-2. The clear detection and intriguing ring structure suggest that c-C3H2 has the potential to become a useful probe of radiation penetration in disks.