Chemical and physical characterization of collapsing low-mass prestellar dense cores

TL;DR

This study combines hydrodynamical modeling with gas-grain chemistry to characterize the physical and chemical evolution of prestellar core collapse, identifying potential chemical tracers for different core components and magnetic field properties.

Contribution

It introduces a coupled hydrodynamical and chemical model to differentiate core components and magnetic field effects in prestellar collapse, aiding observational identification.

Findings

Certain chemical species can distinguish core components.

Chemical signatures vary with magnetic field strength and orientation.

Proposed tracers can guide future astronomical observations.

Abstract

The first hydrostatic core, also called the first Larson core, is one of the first steps in low-mass star formation, as predicted by theory. With recent and future high performance telescopes, details of these first phases become accessible, and observations may confirm theory and even bring new challenges for theoreticians. In this context, we study from a theoretical point of view the chemical and physical evolution of the collapse of prestellar cores until the formation of the first Larson core, in order to better characterize this early phase in the star formation process. We couple a state-of-the-art hydrodynamical model with full gas-grain chemistry, using different assumptions on the magnetic field strength and orientation. We extract the different components of each collapsing core (i.e., the central core, the outflow, the disk, the pseudodisk, and the envelope) to highlight their specific physical and chemical characteristics. Each component often presents a specific physical history, as well as a specific chemical evolution. From some species, the components can clearly be differentiated. The different core models can also be chemically differentiated. Our simulation suggests some chemical species as tracers of the different components of a collapsing prestellar dense core, and as tracers of the magnetic field characteristics of the core. From this result, we pinpoint promising key chemical species to be observed.