Fast deuterium fractionation in magnetized and turbulent filaments

Abstract

Deuterium fractionation is considered as an important process to infer the chemical ages of prestellar cores in filaments. We present here the first magneto-hydrodynamical simulations including a chemical network to study deuterium fractionation in magnetized and turbulent filaments and their substructures. The filaments typically show widespread deuterium fractionation with average values $\gtrsim0.01$. For individual cores of similar age, we observe the deuteration fraction to increase with time, but also to be independent of their average properties such as density, virial or mass-to-magnetic flux ratio. We further find a correlation of the deuteration fraction with core mass, average H$_2$ density and virial parameter only at late evolutionary stages of the filament and attribute this to the lifetime of the individual cores. Specifically, chemically old cores reveal higher deuteration fractions. Within the radial profiles of selected cores, we notice differences in the structure of the deuteration fraction or surface density, which we can attribute to their different turbulent properties. High deuteration fractions of the order $0.01-0.1$ may be reached within approximately $200$~kyrs, corresponding to two free-fall times, as defined for cylindrical systems, of the filaments