Similar complex kinematics within two massive, filamentary infrared dark clouds

Abstract

Infrared dark clouds (IRDCs) are thought to be potential hosts of the elusive early phases of high-mass star formation. Here we conduct an in-depth kinematic analysis of one such IRDC, G034.43+00.24 (Cloud F), using high sensitivity and high spectral resolution IRAM-30m N${}_2$H${}^{+}$ ($1-0$) and C${}^{18}$O ($1-0$) observations. To disentangle the complex velocity structure within this cloud we use Gaussian decomposition and hierarchical clustering algorithms. We find that four distinct coherent velocity components are present within Cloud F. The properties of these components are compared to those found in a similar IRDC, G035.39-00.33 (Cloud H). We find that the components in both clouds have: high densities (inferred by their identification in N${}_2$H${}^{+}$), trans-to-supersonic non-thermal velocity dispersions with Mach numbers of $\sim$ $1.5-4$, a separation in velocity of $\sim$3 km s${}^{-1}$, and a mean red-shift of $\sim$ 0.3 km s${}^{-1}$ between the N${}_2$H${}^{+}$ (dense gas) and C${}^{18}$O emission (envelope gas). The latter of these could suggest that these clouds share a common formation scenario. We investigate the kinematics of the larger-scale Cloud F structures, using lower-density-tracing ${}^{13}$CO ($1-0$) observations. A good correspondence is found between the components identified in the IRAM-30m observations and the most prominent component in the${}^{13}$CO data. We find that the IRDC Cloud F is only a small part of a much larger structure, which appears to be an inter-arm filament of the Milky Way.

References in corpus (23)

• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
• The dynamical properties of dense filaments in the infrared dark cloud G035.39-00.33
• On the frequency of N2H+ and N2D+
• Complex, Quiescent Kinematics in a Highly Filamentary Infrared Dark Cloud
• Searching for massive pre--stellar cores through observations of N2H+ and N2D+
• The low frequency radio emission and spectrum of the extended SNR W44: new VLA observations at 74 and 324 MHz
• SMA observations of Infrared Dark Clouds: A tale of two cores
• Molecular Outflows and a Mid-Infrared Census of the Massive Star-Formation Region Associated with IRAS 18507+0121
• Unveiling the Early-Stage Anatomy of a Protocluster Hub with ALMA
• Chemical evolution in the early phases of massive star formation II: Deuteration
• The Supernova Remnant W44: confirmations and challenges for cosmic-ray acceleration
• Molecular Line Observations of Infrared Dark Clouds: Seeking the Precursors to Intermediate and Massive Star Formation
• A Hunt for Massive Starless Cores
• Are fibres in molecular cloud filaments real objects?
• Distributed Low-Mass Star Formation in the IRDC G34.43+00.24
• Temperature structure and kinematics of the IRDC G035.39-00.33
• Widespread SiO and CH3OH emission in Filamentary Infrared Dark Clouds
• ALMA Observations of the IRDC Clump G34.43+00.24 MM3: 278 GHz Class I Methanol Masers
• A multi-wavelength observation and investigation of six infrared dark clouds
• Mid-J CO Shock Tracing Observations of Infrared Dark Clouds III: SLED fitting
• Mid-J CO Shock Tracing Observations of Infrared Dark Clouds I

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• ALMA-IRDC: Dense gas mass distribution from cloud to core scales
• Autonomous Gaussian decomposition of the Galactic Ring Survey. I. Global statistics and properties of the 13CO emission data
• Multicomponent kinematics in a massive filamentary IRDC
• TRAO Survey of the nearby filamentary molecular clouds, the universal nursery of stars (TRAO FUNS). II. Filaments and Dense cores in IC 5146
• The Kinematic Structure of Magnetically Aligned HI Filaments
• ALMA-IRDC II. First high-angular resolution measurements of the 14N/15N ratio in a large sample of infrared-dark cloud cores
• The kinematics of the magnetised protostellar core IRAS15398-3359