# A study of singly deuterated cyclopropenylidene c-C3HD in protostar IRAS 16293-2422

## TL;DR

This study reports the detection and analysis of singly deuterated cyclopropenylidene c-C3HD in the protostar IRAS 16293-2422, highlighting its potential as a tool for probing cold interstellar environments.

## Contribution

First detection of c-C3HD in a protostellar environment and comparison with astrochemical models to understand deuterium fractionation.

## Key findings

- c-C3HD can be used to study cold interstellar chemistry
- Deuterium fraction in c-C3HD is approximately 14%
- Results support the role of c-C3HD in astrochemical diagnostics

## Abstract

Cyclic-C3HD (c-C3HD) is a singly deuterated isotopologue of c-C3H2, which is one of the most abundant and widespread molecules in our Galaxy. We observed IRAS 16293-2422 in the 3 mm band with a single frequency setup using the EMIR heterodyne 3 mm receiver of the IRAM 30m telescope. We observed seven lines of c-C3HD and three lines of c-C3H2. Observed abundances are compared with astrochemical simulations using the NAUTILUS gas-grain chemical model. Our results clearly show that c-C3HD can be used as an important supplement for studying chemistry and physical conditions for cold environments. Assuming that the size of the protostellar envelope is 3000 AU and same excitation temperatures for both c-C3H2 and c-C3HD, we obtain a deuterium fraction of $14_{-3}^{+4}\%$.