ALMA detection of water vapour in the low mass protostar IRAS 16293$-$2422

TL;DR

This study reports the first detection of water vapour emission from the low mass protostar IRAS 16293-2422 using ALMA, providing insights into water abundance in star-forming regions.

Contribution

The paper presents the spectroscopic detection of water vapour in a low mass protostar with detailed measurements of its abundance and excitation temperature, a novel observation in this context.

Findings

Detected water vapour emission line at 183.310 GHz.

Measured water column density as 4.2×10^{16} cm^{-2}.

Estimated water fractional abundance as 1.44×10^{-7}.

Abstract

The low mass protostar IRAS 16293$-$2422 is a well-known young stellar system that is observed in the L1689N molecular cloud in the constellation of Ophiuchus. In the interstellar medium and solar system bodies, water is a necessary species for the formation of life. We present the spectroscopic detection of the rotational emission line of water (H$_{2}$O) vapour from the low mass protostar IRAS 16293$-$2422 using the Atacama Large Millimeter/submillimeter Array (ALMA) band 5 observation. The emission line of H$_{2}$O is detected at frequency $\nu$ = 183.310 GHz with transition J=3$_{1,3}$$-$2$_{2,2}$. The statistical column density of the emission line of water vapour is $N$(H$_{2}$O) = 4.2$\times$10$^{16}$ cm$^{-2}$ with excitation temperature ($T_{ex}$) = 124$\pm$10 K. The fractional abundance of H$_{2}$O with respect to H$_{2}$ is 1.44$\times$10$^{-7}$ where $N$(H$_{2}$) = 2.9$\times$10$^{23}$ cm$^{-2}$.