Does a prestellar core always become protostellar? Tracing the evolution of cores from the prestellar to protostellar phase

TL;DR

This study investigates the conditions under which prestellar cores evolve into protostars, challenging the notion that super-Jeans cores are necessarily unstable, and emphasizes the importance of temperature and external pressure in core evolution.

Contribution

The paper introduces a non-magnetic polytropic model to analyze core stability, highlighting the role of temperature and external pressure in the prestellar to protostellar transition.

Findings

Super-Jeans cores do not necessarily violate Jeans stability.

Temperature and external pressure are critical in core evolution.

Certain thermodynamic conditions can keep cores starless.

Abstract

Recently, a subset of starless cores whose thermal Jeans mass is apparently overwhelmed by the mass of the core has been identified, e.g., the core {\small L183}. In literature, massive cores such as this one are often referred to as "super-Jeans cores". As starless cores are perhaps on the cusp of forming stars, a study of their dynamics will improve our understanding of the transition from the prestellar to the protostellar phase. In the present work we use non-magnetic polytropes belonging originally to the family of the Isothermal sphere. For the purpose, perturbations were applied to individual polytropes, first by replacing the isothermal gas with a gas that was cold near the centre of the polytrope and relatively warm in the outer regions, and second, through a slight compression of the polytrope by raising the external confining pressure. Using this latter configuration we identify thermodynamic conditions under which a core is likely to remain starless. In fact, we also argue that the attribute "super-Jeans" is subjective and that these cores do not formally violate the Jeans stability criterion. On the basis of our test results we suggest that gas temperature in a star-forming cloud is crucial towards the formation and evolution of a core. Simulations in this work were performed using the particle-based Smoothed Particle Hydrodynamics algorithm. However, to establish numerical convergence of the results we suggest similar tests with a grid-scheme, such as the Adaptive mesh refinement.