EVLA Observations of the Barnard 5 Star-Forming Core: Embedded Filaments Revealed

TL;DR

This study uses EVLA and GBT observations to reveal a filamentary structure in the Barnard 5 star-forming core, showing subsonic turbulence and fragmentation consistent with isothermal filament models.

Contribution

First combined EVLA and GBT observations to image filamentary structures and turbulence in the Barnard 5 core at high resolution.

Findings

Revealed a 5,000 AU wide filament in Barnard 5

Observed subsonic turbulence with little spatial variation

Detected fragmentation consistent with Jeans length

Abstract

We present a ~6.5'x8' Expanded Very Large Array (EVLA) mosaic observations of the NH3 (1,1) emission in the Barnard 5 region in Perseus, with an angular resolution of 6". This map covers the coherent region, where the dense gas presents subsonic non-thermal motions (as seen from single dish observations with the Green Bank Telescope, GBT). The combined EVLA and GBT observations reveal, for the first time, a striking filamentary structure (20" wide or 5,000 AU at the distance of Perseus) in this low-mass star forming region. The integrated intensity profile of this structure is consistent with models of an isothermal filament in hydrostatic equilibrium. The observed separation between the B5-IRS1 young stellar object (YSO), in the central region of the core, and the northern starless condensation matches the Jeans length of the dense gas. This suggests that the dense gas in the coherent region is fragmenting. The region observed displays a narrow velocity dispersion, where most of the gas shows evidence for subsonic turbulence, and where little spatial variations are present. It is only close to the YSO where an increase in the velocity dispersion is found, but still displaying subsonic non-thermal motions