ALMA Observations of the IRDC Clump G34.43+00.24 MM3: DNC/HNC Ratio

Abstract

We have observed the clump G34.43+00.24 MM3 associated with an infrared dark cloud in DNC $J$=3--2, HN${}^{13}$C $J$=3--2, and N${}_2$H${}^{+}$ $J$=3--2 with the Atacama Large Millimeter/submillimeter Array (ALMA). The N${}_2$H${}^{+}$ emission is found to be relatively weak near the hot core and the outflows, and its distribution is clearly anti-correlated with the CS emission. This result indicates that a young outflow is interacting with cold ambient gas. The HN${}^{13}$C emission is compact and mostly emanates from the hot core, whereas the DNC emission is extended around the hot core. Thus, the DNC and HN${}^{13}$C emission traces warm regions near the protostar differently. The DNC emission is stronger than the HN${}^{13}$C emission toward most parts of this clump. The DNC/HNC abundance ratio averaged within a $15^{\prime \prime }\times 15^{\prime \prime }$ area around the phase center is higher than 0.06. This ratio is much higher than the value obtained by the previous single-dish observations of DNC and HN${}^{13}$C $J$=1--0 ($\sim$0.003). It seems likely that the DNC and HNC emission observed with the single-dish telescope traces lower density envelopes, while that observed with ALMA traces higher density and highly deuterated regions. We have compared the observational results with chemical-model results in order to investigate the behavior of DNC and HNC in the dense cores. Taking these results into account, we suggest that the low DNC/HNC ratio in the high-mass sources obtained by the single-dish observations are at least partly due to the low filling factor of the high density regions.

arXiv commentaccepted to ApJ

References in corpus (28)

• Embedded Clusters in Molecular Clouds
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores
• Infrared Dark Clouds: precursors to star clusters
• A three-phase chemical model of hot cores: the formation of glycine
• Chemistry in Infrared Dark Cloud Clumps: a Molecular Line Survey at 3 mm
• The importance of the ortho:para H2 ratio for the deuteration of molecules during pre-protostellar collapse
• A Unified Monte Carlo Treatment of Gas-Grain Chemistry for Large Reaction Networks. II. A Multiphase Gas-Surface-Layered Bulk Model
• From Prestellar to Protostellar Cores II. Time Dependence and Deuterium Fractionation
• Multilayer formation and evaporation of deuterated ices in prestellar and protostellar cores
• Massive Protostars in the Infrared Dark Cloud MSXDC G034.43+00.24
• New extended deuterium fractionation model: assessment at dense ISM conditions and sensitivity analysis
• Water in Protoplanetary Disks: Deuteration and Turbulent Mixing
• Ortho-H2 and the Age of Interstellar Dark Clouds
• A Molecular Line Observation toward Massive Clumps Associated with Infrared Dark Clouds
• Molecular Outflows and a Mid-Infrared Census of the Massive Star-Formation Region Associated with IRAS 18507+0121
• Annual Parallax Measurements of an Infrared Dark Cloud MSXDC G034.43+00.24 with VERA
• Molecular outflows within the filamentary infrared dark cloud G34.43+0.24
• CH2D+, the Search for the Holy Grail
• Carbon Isotope and Isotopomer Fractionation in Cold Dense Cloud Cores
• DNC/HNC Ratio of Massive Clumps in Early Evolutionary Stages of High-Mass Star Formation
• Distances to Dark Clouds: Comparing Extinction Distances to Maser Parallax Distances
• Distributed Low-Mass Star Formation in the IRDC G34.43+00.24
• DNC/HNC and N2D+/N2H+ ratios in high-mass star forming cores
• Water deuterium fractionation in the high-mass star-forming region G34.26+0.15 based on Herschel/HIFI data
• ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Hot Core and Molecular Outflows
• ALMA Observations of the IRDC Clump G34.43+00.24 MM3: 278 GHz Class I Methanol Masers
• Detection of Two Carbon-Chain-Rich Cores; CB130-3 and L673-SMM4

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• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). IX. Physical Properties and Spatial Distribution of Cores in IRDCs
• Magnetic fields in the infrared dark cloud G34.43+0.24
• Astrochemical Properties of Planck Cold Clumps
• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). V. Deuterated Molecules in the 70 $\mu$m dark IRDC G14.492-00.139
• Molecular Cloud Cores with High Deuterium Fraction: Nobeyama Single-Pointing Survey
• ALMA Observations of the IRDC Clump G34.43+00.24 MM3: Complex Organic and Deuterated Molecules
• Molecular Cloud Cores with High Deuterium Fractions: Nobeyama Mapping Survey
• Digging into the Interior of Hot Cores with ALMA (DIHCA). V. Deuterium Fractionation of Methanol
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