Using Chemistry to Unveil the Kinematics of Starless Cores: Complex Radial Motions in Barnard 68

TL;DR

This study uses molecular line observations and chemical modeling to reveal complex radial motions, including oscillations, in the starless core Barnard 68, suggesting it is older than previously estimated.

Contribution

It introduces a method combining chemical networks and radiative transfer to determine radial velocity profiles in starless cores, revealing oscillatory motions.

Findings

Detection of inward and outward radial motions indicating oscillations.

Barnard 68 is likely older than chemical and statistical estimates suggest.

Chemistry can effectively constrain kinematic profiles of starless cores.

Abstract

We present observations of 13CO, C18O, HCO+, H13CO+, DCO+ and N2H+ line emission towards the Barnard 68 starless core. The line profiles are interpreted using a chemical network coupled with a radiative transfer code in order to reconstruct the radial velocity profile of the core. Our observations and modeling indicate the presence of complex radial motions, with the inward motions in the outer layers of the core but outward motions in the inner part, suggesting radial oscillations. The presence of such oscillation would imply that B68 is relatively old, typically one order of magnitude older than the age inferred from its chemical evolution and statistical core lifetimes. Our study demonstrates that chemistry can be used as a tool to constrain the radial velocity profiles of starless cores.