Infall of material onto the filaments in Barnard 5

¹ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
² Korea Astronomy and Space Science Institute, 776 Daedeok-daero Yuseong-gu, Daejeon 34055, Republic of Korea
e-mail: spandan@kasi.re.kr
³ The Department of Physics, Engineering Physics & Astronomy, Queen’s University, Stirling Hall, 64 Bader Lane, Kingston, ON K7L 3N6, Canada
⁴ Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA

Received: 30 June 2023
Accepted: 8 December 2023

Abstract

Aims. We aim to study the structure and kinematics of the two filaments inside the subsonic core Barnard 5 in Perseus using high-resolution (≈2400 au) NH₃ data and a multi-component fit analysis.

Methods. We used observations of NH₃(1,1) and (2,2) inversion transitions using the Very Large Array (VLA) and the Green Bank Telescope (GBT). We smoothed the data to a beam of 8" to reliably fit multiple velocity components towards the two filamentary structures identified in B5.

Results. Along with the core and cloud components, which dominate the flux in the line of sight, we detected two components towards the two filaments showing signs of infall. We also detected two additional components that can possibly trace new material falling into the subsonic core of B5.

Conclusions. Following a comparison with previous simulations of filament formation scenarios in planar geometry, we conclude that either the formation of the B5 filaments is likely to be rather cylindrically symmetrical or the filaments are magnetically supported. We also estimate infall rates of 1.6 × 10⁻⁴ M_⊙ yr⁻¹ and 1.8 × 10⁻⁴ M_⊙ yr⁻¹ (upper limits) for the material being accreted onto the two filaments. At these rates, the filament masses can change significantly during the core lifetime. We also estimate an upper limit of 3.5 × 10⁻⁵ M_⊙ yr⁻¹ for the rate of possible infall onto the core itself. Accretion of new material onto cores indicates the need for a significant update to current core evolution models, where cores are assumed to evolve in isolation.