Environment and Protostellar Evolution

TL;DR

This paper models how environmental pressure influences the evolution, appearance, and chemistry of low-mass protostars, revealing that high-pressure environments lead to smaller, denser cores with higher accretion rates and altered observational signatures.

Contribution

It provides unified analytic and numerical models linking environmental pressure to protostellar evolution, accretion, outflows, and astrochemical processes, highlighting the impact of pressure on star formation.

Findings

High-pressure environments produce smaller, denser prestellar cores.

Protostars in high-pressure regions have higher luminosities and more powerful outflows.

Environmental pressure significantly affects infrared morphology and CO chemistry.

Abstract

Even today in our Galaxy, stars form from gas cores in a variety of environments, which may affect the properties of resulting star and planetary systems. Here we study the role of pressure, parameterized via ambient clump mass surface density, on protostellar evolution and appearance, focussing on low-mass, Sun-like stars and considering a range of conditions from relatively low pressure filaments in Taurus, to intermediate pressures of cluster-forming clumps like the Orion Nebula Cluster (ONC), to very high pressures that may be found in the densest Infrared Dark Clouds (IRDCs) or in the Galactic Center (GC). We present unified analytic and numerical models for collapse of prestellar cores, accretion disks, protostellar evolution and bipolar outflows, coupled to radiative transfer (RT) calculations and a simple astrochemical model to predict CO gas phase abundances. Prestellar cores in high pressure environments are smaller and denser and thus collapse with higher accretion rates and efficiencies, resulting in higher luminosity protostars with more powerful outflows. The protostellar envelope is heated to warmer temperatures, affecting infrared morphologies (and thus classification) and astrochemical processes like CO depletion to dust grain ice mantles (and thus CO morphologies). These results have general implications for star and planet formation, especially via their effect on astrochemical and dust grain evolution during infall to and through protostellar accretion disks.