Astrochemistry as a tool to follow the protostellar evolution: the Class I stage

TL;DR

This paper reviews the use of astrochemistry, focusing on complex organic and deuterated molecules, to study the early stages of star formation, especially the Class I protostellar phase, and presents new observations of specific molecules in SVS13-A.

Contribution

It provides a review of existing chemical observations in Class I protostars and introduces new data on deuterated molecules in SVS13-A to enhance understanding of protostellar evolution.

Findings

New observations of deuterated cyanoacetylene and thioformaldehyde in SVS13-A.

Comparison of molecular deuteration across different protostellar stages.

Insights into the chemical and physical structure of Class I protostars.

Abstract

The latest developments in astrochemistry have shown how some molecular species can be used as a tool to study the early stages of the solar-type star formation process. Among them, the more relevant species are the interstellar complex organic molecules (iCOMs) and the deuterated molecules. Their analysis give us information on the present and past history of protostellar objects. Among the protostellar evolutionary stages, Class I protostars represent a perfect laboratory in which to study the initial conditions for the planet formation process. Indeed, from a physical point of view, the Class I stage is the bridge between the Class 0 phase, dominated by the accretion process, and the protoplanetary disk phase, when planets form. Despite their importance, few observations of Class I protostars exist and very little is known about their chemical content. In this paper we review the (few) existing observations of iCOMs and deuterated species in Class I protostars. In addition, we present new observations of deuterated cyanoacetylene and thioformaldehyde towards the Class I protostar SVS13-A. These new observations allow us to better understand the physical and chemical structure of SVS13-A and compare the cyanoacetylene and thioformaldehyde deuteration with other sources in different evolutionary phases.