Chemical properties of two dense cores in a Planck Galactic Cold Clump G168.72-15.48

Abstract

To deepen our understanding of the chemical properties of the Planck Galactic Cold Clump (PGCC) G168.72-15.48, we performed observations of nine molecular species, namely, \ce{c-C3H}, \ce{H2CO}, \ce{HC5N}, \ce{HC7N}, \ce{SO}, \ce{CCH}, \ce{N2H+}, \ce{CH3OH}, and \ce{CH3CCH}, toward two dense cores in PGCC G168.72-15.48 using the Tianma Radio Telescope and Purple Mountain Observatory Telescope. We detected \ce{c-C3H}, \ce{H2CO}, \ce{HC5N}, \ce{N2H+}, \ce{CCH}, and \ce{CH3OH} in both G168-H1 and G168-H2 cores, whereas \ce{HC7N} and \ce{CH3CCH} were detected only in G168-H1 and SO was detected only in G168-H2. Mapping observations reveal that the \ce{CCH}, \ce{N2H+}, \ce{CH3OH}, and \ce{CH3CCH} emissions are well coupled with the dust emission in G168-H1. Additionally, \ce{N2H+} exhibits an exceptionally weak emission in the denser and more evolved G168-H2 core, which may be attributed to the \ce{N2H+} depletion. We suggest that the \ce{N2H+} depletion in G168-H2 is dominated by \ce{N2} depletion, rather than the destruction by CO. The local thermodynamic equilibrium calculations indicate that the carbon-chain molecules of \ce{CCH}, \ce{HC5N}, \ce{HC7N}, and \ce{CH3CCH} are more abundant in the younger G168-H1 core. We found that starless core G168-H1 may have the properties of cold dark clouds based on its abundances of carbon-chain molecules. While, the prestellar core G168-H2 exhibits lower carbon-chain molecular abundances than the general cold dark clouds. With our gas-grain astrochemical model calculations, we attribute the observed chemical differences between G168-H1 and G168-H2 to their different gas densities and different evolutionary stages.

References in corpus (50)

• Dust Grain Size Distributions and Extinction in the Milky Way, LMC, and SMC
• A computer program for fast non-LTE analysis of interstellar line spectra
• The Relation Between Optical Extinction and Hydrogen Column Density in the Galaxy
• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Probing the evolutionary status of starless cores through N2H+ and N2D+ observations
• How to Calculate Molecular Column Density
• N2H+ and C18O Depletion in a Cold Dark Cloud
• Chemistry of Dark Clouds: Databases, Networks, and Models
• Polycylcic Aromatic Hydrocarbons (PAH's) in dense cloud chemistry
• Reaction Networks For Interstellar Chemical Modelling: Improvements and Challenges
• The origin of complex organic molecules in prestellar cores
• Molecular Evolution in Collapsing Prestellar Cores
• Chemistry in Disks. IV. Benchmarking gas-grain chemical models with surface reactions
• On the reservoir of sulphur in dark clouds : chemistry and elemental abundance reconciled
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• Modeling Sulfur Depletion in Interstellar Clouds
• Multilayer modeling of porous grain surface chemistry I. The GRAINOBLE model
• Multi-temperature mapping of dust structures throughout the Galactic Plane using the PPMAP tool with Herschel Hi-GAL data
• Sulphur chemistry in the L1544 pre-stellar core
• CCS Imaging of the Starless Core L1544: An Envelope with Infall and Rotation
• Planck 2015 results. XXVIII. The Planck Catalogue of Galactic Cold Clumps
• The gas-phase chemistry of carbon chains in dark cloud chemical models
• Gas emissions in Planck cold dust clumps---A Survey of the J=1-0 Transitions of ${}^{12}$CO, ${}^{13}$CO, and C${}^{18}$O
• An analytic column density profile to fit prestellar cores
• The Thermal Structure of Gas in Pre-Stellar Cores: A Case Study of Barnard 68
• A Molecular Line Observation toward Massive Clumps Associated with Infrared Dark Clouds
• Abundant cyanopolyynes as a probe of infall in the Serpens South cluster-forming region
• The TOP-SCOPE survey of Planck Galactic Cold Clumps: Survey overview and results of an exemplar source, PGCC G26.53+0.17
• Gas-phase CO depletion and N2H+ abundances in starless cores
• An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus Molecular Cloud : I. Physical Properties of Filaments and Dense cores
• The Initial Conditions of Clustered Star Formation. II. N2H+ Observations of the Ophiuchus B Core
• Organic species in Infrared Dark Clouds
• Molecular Line Observations of Carbon-Chain-Producing Regions L1495B and L1521B
• Molecular environments of 51 Planck cold clumps in Orion complex
• Detection of HC${}_5$N and HC${}_7$N Isotopologues in TMC-1 with the Green Bank Telescope
• Organic chemistry in the dark clouds L1448 and L183. A Unique grain mantle composition
• The JCMT and Herschel Gould Belt Surveys: A comparison of SCUBA-2 and Herschel data of dense cores in the Taurus dark cloud L1495
• Survey Observations to Study Chemical Evolution from High-mass Starless Cores to High-mass Protostellar Objects I: HC3N and HC5N
• TMRT Observations of Carbon-chain molecules in Serpens South 1A
• Nautilus multi-grain model: Importance of cosmic-ray-induced desorption in determining the chemical abundances in the ISM
• Widespread Presence of Glycolaldehyde and Ethylene Glycol Around Sagittarius B2
• Chemical modeling of the L1498 and L1517B prestellar cores: CO and HCO+ depletion
• The properties of Planck Galactic cold clumps in the L1495 dark cloud
• An Ammonia Spectral Map of the L1495-B218 Filaments in the Taurus Molecular Cloud: II CCS & HC${}_7$N Chemistry and Three Modes of Star Formation in the Filaments
• Survey Observations to Study Chemical Evolution from High-Mass Starless Cores to High-Mass Protostellar Objects II. HC${}_3$N and N${}_2$H${}^{+}$
• A search for Cyanopolyynes in L1157-B1
• High-angular resolution observations of methanol in the infrared dark cloud core G11.11-0.12P1
• Interstellar chemical differentiation across grain sizes
• Effects of turbulent dust grain motion to interstellar chemistry
• A particular carbon-chain-producing region: L1489 starless core

Cited by in corpus (1)

• GGCHEMPY: A pure Python-based gas-grain chemical code for efficient simulation of interstellar chemistry