On the stability of nonisothermal Bonnor-Ebert spheres
III. The role of chemistry in core stabilization
1 Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstr. 1, 85748 Garching, Germany
2 Department of Physics, PO Box 64, 00014 University of Helsinki, Finland
Received: 28 November 2016
Accepted: 21 March 2017
Aims. We investigate the effect of chemistry on the stability of starless cores against gravitational collapse.
Methods. We combined chemical and radiative transfer simulations in the context of a modified Bonnor-Ebert sphere to model the effect of chemistry on the gas temperature, and study the effect of temperature changes on core stability.
Results. We find that chemistry has in general very little effect on the nondimensional radius ξout, which parametrizes the core stability. Cores that are initially stable or unstable tend to stay near their initial states, in terms of stability (i.e., ξout ~ const.), as the chemistry develops. This result is independent of the initial conditions. We can however find solutions where ξout decreases at late times (t ≳ 106 yr), which correspond to increased stabilization caused by the chemistry. Even though the core stability is unchanged by the chemistry in most of the models considered here, we cannot rule out the possibility that a core can evolve from an unstable to a stable state owing to chemical evolution. The reverse case, where an initially stable core becomes ultimately unstable, seems highly unlikely.
Conclusions. Our results indicate that chemistry should be properly accounted for in studies of star-forming regions, and that further investigations of core stability especially with hydrodynamical models are warranted.
Key words: ISM: clouds / ISM: molecules / radiative transfer
© ESO, 2017