On the simultaneous evolution of massive protostars and their host cores

TL;DR

This paper investigates the coupled evolution of massive protostars and their host cores using advanced radiation hydrodynamics and stellar evolution models, revealing diverse interdependencies influenced by feedback and accretion timing.

Contribution

It introduces a multi-dimensional simulation framework that simultaneously models protostellar and core evolution, highlighting the importance of feedback effects and accretion timing.

Findings

Protostellar and core evolution are highly interdependent and vary with accretion timing.

Feedback mechanisms influence protostar properties on short timescales.

Pre-computed stellar tracks can approximate evolution under certain conditions.

Abstract

Studies of the evolution of massive protostars and the evolution of their host molecular cloud cores are commonly treated as separate problems. However, interdependencies between the two can be significant. Here, we study the simultaneous evolution of massive protostars and their host molecular cores using a multi-dimensional radiation hydrodynamics code that incorporates the effects of the thermal pressure and radiative acceleration feedback of the centrally forming protostar. The evolution of the massive protostar is computed simultaneously using the stellar evolution code STELLAR, modified to include the effects of variable accretion. The interdependencies are studied in three different collapse scenarios. For comparison, stellar evolutionary tracks at constant accretion rates and the evolution of the host cores using pre-computed stellar evolutionary tracks are computed. The resulting interdependencies of the protostellar evolution and the evolution of the environment are extremely diverse and depend on the order of events, in particular the time of circumstellar accretion disk formation with respect to the onset of the bloating phase of the star. Feedback mechanisms affect the instantaneous accretion rate and the protostar's radius, temperature and luminosity on timescales equal or smaller than 5 kyr, corresponding to the accretion timescale and Kelvin-Helmholtz contraction timescale, respectively. Nevertheless, it is possible to approximate the overall protostellar evolution in many cases by pre-computed stellar evolutionary tracks assuming appropriate constant average accretion rates.