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

Abstract

We have observed the 70 $\mu$m dark infrared dark cloud (IRDC) G14.492-00.139 in the N${}_2$D${}^{+}$ $J$=3--2, DCO${}^{+}$ $J$=3--2, DCN $J$=3--2, and C${}^{18}$O $J$=2--1 lines, using the Atacama Large Millimeter/submillimeter Array (ALMA) as part of the ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). We find that the spatial distribution is different among the observed emission from the deuterated molecular lines. The N${}_2$D${}^{+}$ emission traces relatively quiescent regions, while both the DCO${}^{+}$ and DCN emission emanates mainly from regions with signs of active star-formation. In addition, the DCO${}^{+}$/N${}_2$D${}^{+}$ ratio is found to be lower in several dense cores than in starless cores embedded in low-mass star-forming regions. By comparing the observational results with chemical model calculations, we discuss the origin of the low DCO${}^{+}$/N${}_2$D${}^{+}$ ratio in this IRDC clump. The low DCO${}^{+}$/N${}_2$D${}^{+}$ ratio can be explained if the temperature of the dense cores is in the range between the sublimation temperature of N${}_2$ ($\sim$20 K) and CO ($\sim$25 K). The results suggest that the dense cores in G14.492-00.139 are warmer and denser than the dense cores in low-mass star-forming regions.

accepted for publication in ApJ

References in corpus (11)

• Non-thermal desorption from interstellar dust grains via exothermic surface reactions
• The 2014 KIDA network for interstellar chemistry
• A cosmic abundance standard: chemical homogeneity of the solar neighbourhood and the ISM dust-phase composition
• The ALMA Survey of 70 $\mu \mathrm{m}$ Dark High-mass Clumps in Early Stages (ASHES). II: Molecular Outflows in the Extreme Early Stages of Protocluster Formation
• A Hunt for Massive Starless Cores
• Massive and low-mass protostars in massive "starless" cores
• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477
• ALMA observations of NGC 6334S $-$ I: Forming massive stars and cluster in subsonic and transonic filamentary clouds
• The ALMA Survey of 70$\mu$m Dark High-mass Clumps in Early Stages (ASHES) III. A Young Molecular Outflow Driven by a Decelerating Jet
• A Low-mass Cold and Quiescent Core Population in a Massive Star Protocluster
• ALMA Observations of the IRDC Clump G34.43+00.24 MM3: DNC/HNC Ratio

Cited by in corpus (14)

• 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
• Evidence of high-mass star formation through multi-scale mass accretion in hub-filament-system clouds
• The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VIII. Dynamics of Embedded Dense Cores
• The core population and kinematics of a massive clump at early stages: an ALMA view
• The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VI. The core-scale CO-depletion
• The ALMA Survey of 70 $\mu \mathrm{m}$ Dark High-mass Clumps in Early Stages (ASHES). VII: Chemistry of Embedded Dense Cores
• ALMA-IMF. VII. First release of the full spectral line cubes: Core kinematics traced by DCN J=(3-2)
• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Evidence for a Molecular Jet Launched at an Unprecedented Early Phase of Protostellar evolution
• Fragmentation of the High-mass "Starless'' Core G10.21-0.31: a Coherent Evolutionary Picture for Star Formation
• ALMAGAL IV. Morphological comparison of molecular and thermal dust emission using the histogram of oriented gradients (HOG) method
• Digging into the Interior of Hot Cores with ALMA (DIHCA). V. Deuterium Fractionation of Methanol
• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). XII. Unanchored Forked Stream in the Propagating Path of a Protostellar Outflow
• Molecular deuterations in massive Starless Clump Candidates
• DCO${}^{+}$ and DCN 1-0 survey toward a sample of Planck cold clumps