VLA and NOEMA view of the Bok Globule CB 17: the starless nature of a proposed FHSC candidate

Abstract

We use 3mm continuum NOEMA and NH${}_3$ VLA observations towards the First Hydrostatic Core (FHSC) candidate CB 17 MMS to reveal the dust structure and gas properties down to 600-1,100 au scales and constrain its evolutionary stage. We do not detect any compact source at the previously identified 1.3 mm point source, despite expecting a minimum signal-to-noise of 9. The gas traced by NH${}_3$ exhibits subsonic motions, with an average temperature of 10.4 K. A fit of the radial column density profile derived from the ammonia emission finds a flat inner region of radius $\sim$1,800 au and a central density of $\sim$6$\times 10^5$ cm${}^{-3}$. Virial and density structure analysis reveals the core is marginally bound (${\alpha }_{vir}$= 0.73). The region is entirely consistent with a young starless core, hence ruling out CB 17 MMS as a FHSC candidate. Additionally, the core exhibits a velocity gradient aligned with the major axis, showing an arc-like structure in the p-v diagram and an off-center region with high-velocity dispersion caused by two distinct velocity peaks. These features could be due to interaction with the nearby outflow, which appears to deflect due to the dense gas near the NH${}_3$ column density peak. We investigate the specific angular momentum profile of the starless core, finding that it aligns closely with previous studies of such radial profiles in Class 0 sources. This similarity to more evolved objects suggests that motions at 1,000 au scales are determined by large-scale dense cloud motions and may be preserved through the early stages of star formation.

References in corpus (18)

• Cold Dark Clouds: The Initial Conditions for Star Formation
• Observing the gas temperature drop in the high-density nucleus of L 1544
• An Ammonia Spectral Atlas of Dense Cores in Perseus
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• The Different Structures of the Two Classes of Starless Cores
• Radiation Magnetohydrodynamics Simulation of Proto-Stellar Collapse: Two-Component Molecular Outflow
• OVRO N2H+ Observations of Class 0 Protostars: Constraints on the Formation of Binary Stars
• The evolutionary state of the southern dense core Cha-MMS1
• Nascent bipolar outflows associated with the first hydrostatic core candidates Barnard 1b-N and 1b-S
• An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus Molecular Cloud : I. Physical Properties of Filaments and Dense cores
• ALMA observations of envelopes around first hydrostatic core candidates
• Rotating filament in Orion B: Do cores inherit their angular momentum from their parent filament?
• A low-velocity bipolar outflow from a deeply embedded object in Taurus revealed by the Atacama Compact Array
• The Earliest Phases of Star formation (EPoS): Temperature, density, and kinematic structure of the star-forming core CB 17
• Synthetic molecular line observations of the first hydrostatic core from chemical calculations
• The dynamically young outflow of the Class 0 protostar Cha-MMS1
• A turbulent origin for the complex envelope kinematics in the young low-mass core Per-Bolo 58
• What can the SEDs of first hydrostatic core candidates reveal about their nature?

Cited by in corpus (3)

• An Interferometric View of H-MM1. I. Direct Observation of NH3 Depletion
• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Evidence for a Molecular Jet Launched at an Unprecedented Early Phase of Protostellar evolution
• Insights into the first and second hydrostatic core stages from numerical simulations