Warm Cores around Regions of Low-Mass Star Formation

TL;DR

This paper models the chemistry of warm cores around low-mass protostars, highlighting the role of temperature-dependent sublimation of ices and resulting molecular variations, consistent with observations of sources like IRAS 16293-2422.

Contribution

It introduces a detailed chemical model incorporating laboratory data on ice sublimation, explaining spatial and temporal molecular variations in warm cores.

Findings

Sublimation occurs in specific temperature bands affecting chemistry.

Model results align with observational data for IRAS 16293-2422.

Chemistry of warm cores can be described by models similar to hot cores.

Abstract

Warm cores (or hot corinos) around low-mass protostellar objects show a rich chemistry with strong spatial variations. This chemistry is generally attributed to the sublimation of icy mantles on dust grains initiated by the warming effect of the stellar radiation. We have used a model of the chemistry in warm cores in which the sublimation process is based on extensive laboratory data; these data indicate that sublimation from mixed ices occurs in several well-defined temperature bands. We have determined the position of these bands for the slow warming by a solar-mass star. The resulting chemistry is dominated by the sublimation process and by subsequent gas-phase reactions; strong spatial and temporal variations in certain molecular species are found to occur, and our results are, in general, consistent with observational results for the well-studied source IRAS 16293-2422. The model used is similar to one that describes the chemistry of hot cores. We infer that the chemistry of both hot cores and warm cores may be described by the same model (suitably adjusted for different physical parameters).