A turbulent origin for the complex envelope kinematics in the young low-mass core Per-Bolo 58

TL;DR

This study investigates the complex envelope kinematics of the young low-mass core Per-Bolo 58, revealing turbulent and magnetic influences through high-resolution molecular line observations and MHD simulations.

Contribution

It demonstrates that turbulent and magnetic effects can produce the observed complex kinematics in a young core, supported by synthetic MHD models matching observations.

Findings

Two distinct velocity components observed in the core.

Synthetic MHD models reproduce the two velocity components.

Large-scale filamentary accretion may influence core kinematics.

Abstract

We use CARMA 3mm continuum and molecular lines (NH2D, N2H+, HCO+, HCN and CS) at ~1000 au resolution to characterize the structure and kinematics of the envelope surrounding the deeply embedded first core candidate Per-Bolo 58. The line profile of the observed species shows two distinct peaks separated by 0.4-0.6 km/s, most likely arising from two different optically thin velocity components rather than the product of self-absorption in an optically thick line. The two velocity components, each with a mass of ~0.5-0.6 Msun, overlap spatially at the position of the continuum emission, and produce a general gradient along the outflow direction. We investigate whether these observations are consistent with infall in a turbulent and magnetized envelope. We compare the morphology and spectra of the N2H+(1-0) with synthetic observations of an MHD simulation that considers the collapse of an isolated core that is initially perturbed with a turbulent field. The proposed model matches the data in the production of two velocity components, traced by the isolated hyperfine line of the N2H+(1-0) spectra and shows a general agreement in morphology and velocity field. We also use large maps of the region to compare the kinematics of the core with that of the surrounding large-scale filamentary structure and find that accretion from the large-scale filament could also explain the complex kinematics exhibited by this young dense core.