Differences in chemical evolution between isolated and embedded prestellar cores

Abstract

Models of prestellar cores often assume that the cores are isolated from their environment - material outside the core boundary plays no role in the subsequent evolution. This is unlikely to be the case in reality, where cores are located within hierarchically substructured molecular clouds. We investigate the dynamical and chemical evolution of prestellar cores, modelled as Bonnor-Ebert spheres, and show that the density of the ambient medium has a large impact on the resulting chemical properties of the cores. Models embedded in high-density, low-temperature surroundings have greatly enhanced abundances of several molecules, such as CO and CS, compared to models with more diffuse surroundings, corresponding to relatively isolated cores. The predicted intensities and profile shapes of molecular lines are also affected. The density of the ambient medium has a stronger effect on the chemical evolution than whether the cores are initially in or out of equilibrium. This suggests that the impact of environment cannot be neglected when modelling chemistry in prestellar cores; the results of these models are highly sensitive to the assumptions made about the core surroundings.

7 pages, 5 figures. MNRAS accepted

References in corpus (9)

• Cold Dark Clouds: The Initial Conditions for Star Formation
• UCLCHEM: A Gas-Grain Chemical Code
• The dynamics of collapsing cores and star formation
• Smoothed Particle Hydrodynamics simulations of expanding HII regions. I. Numerical methods and tests
• An ALMA study of hub-filament systems I. On the clump mass concentration within the most massive cores
• The accretion history of high-mass stars: An ArTéMiS pilot study of Infrared Dark Clouds
• GASTON: Galactic Star Formation with NIKA2. Evidence for the mass growth of star-forming clumps
• Non-ideal MHD simulations of subcritical prestellar cores with non-equilibrium chemistry
• The initial magnetic criticality of prestellar cores