Gaseous CO Abundance---An Evolutionary Tracer for Molecular Clouds

Abstract

Planck cold clumps are among the most promising objects to investigate the initial conditions of the evolution of molecular clouds. In this work, by combing the dust emission data from the survey of Planck satellite with the molecular data of ${}^{12}$CO/${}^{13}$CO (1-0) lines from observations with the Purple Mountain Observatory (PMO) 13.7 m telescope, we investigate the CO abundance, CO depletion and CO-to-H${}_2$ conversion factor of 674 clumps in the early cold cores (ECC) sample. The median and mean values of the CO abundance are 0.89$\times 10^{-4}$ and 1.28$\times 10^{-4}$, respectively. The mean and median of CO depletion factor are 1.7 and 0.9, respectively. The median value of $X_{CO-to-H_2}$ for the whole sample is $2.8\times 10^{20}$ cm${}^{-2}$K${}^{-1}$km${}^{-1}$ s. The CO abundance, CO depletion factor and CO-to-H${}_2$ conversion factor are strongly (anti-)correlated to other physical parameters (e.g. dust temperature, dust emissivity spectral index, column density, volume density and luminosity-to-mass ratio). To conclude, the gaseous CO abundance can be used as an evolutionary tracer for molecular clouds.

20 pages, 4 figures, Accepted to ApJL

References in corpus (6)

• Cold Dark Clouds: The Initial Conditions for Star Formation
• A Herschel [CII] Galactic plane survey I: the global distribution of ISM gas components
• CO Isotopologues in the Perseus Molecular Cloud Complex: the X-Factor and Regional Variations
• The relation between gas and dust in the Taurus Molecular Cloud
• The N2D+/N2H+ ratio as an evolutionary tracer of Class 0 protostars
• Probing the initial conditions of High Mass Star formation -- I. Deuteration and depletion in high mass pre/protocluster clumps

Cited by in corpus (25)

• ATLASGAL-selected massive clumps in the inner Galaxy: I. CO depletion and isotopic ratios
• A holistic perspective on the dynamics of G035.39-00.33: the interplay between gas and magnetic fields
• The TOP-SCOPE survey of Planck Galactic Cold Clumps: Survey overview and results of an exemplar source, PGCC G26.53+0.17
• Star formation laws in both Galactic massive clumps and external galaxies: An extensive study with dust continuum, HCN (4-3), and CS (7-6)
• The Physical Drivers and Observational Tracers of CO-to-H2 Conversion Factor Variations in Nearby Barred Galaxy Centers
• ATLASGAL-selected massive clumps in the inner Galaxy: VI. Kinetic temperature and spatial density measured with formaldehyde
• SCOPE: SCUBA-2 Continuum Observations of Pre-protostellar Evolution - Survey Description and Compact Source Catalogue
• Planck cold clumps in the $\lambda$ Orionis complex: I. Discovery of an extremely young Class 0 protostellar object and a proto-brown dwarf candidate in a bright rimmed clump PGCC G192.32-11.88
• Interplay of gas and ice during cloud evolution
• Dense gas in molecular cores associated with Planck Galactic cold clumps
• The chemical structure of young high-mass star-forming clumps: (II) parsec-scale CO depletion and deuterium fraction of $\mathrm{HC}{\mathrm{O}}^{+}$
• How chemistry influences cloud structure, star formation, and the IMF
• The properties of Planck Galactic cold clumps in the L1495 dark cloud
• Molecular Dynamics in Dissociative Electron Attachment to CO probed by Velocity Slice Imaging
• Modelling the Molecular Gas in NGC 6240
• C2H N=1-0 and N2H+ J=1-0 observations of Planck Galactic cold clumps
• The TOP-SCOPE survey of PGCCs: PMO and SCUBA-2 observations of 64 PGCCs in the 2nd Galactic Quadrant
• A correlation between chemistry, polarization and dust properties in the Pipe Nebula starless core FeSt 1-457
• A FAST Survey of HINSA in PGCCs Guided by HC3N
• H${}^{13}$CN-HN${}^{13}$C intensity ratio as a temperature indicator of interstellar clouds
• History-independent tracers: Forgetful molecular probes of the physical conditions of the dense interstellar medium
• Star formation conditions in a Planck Galactic Cold Clump, G108.84-00.81
• A multi-line study of the filamentary infrared dark cloud G351.78-0.54
• On the Scarcity of Dense Cores ($n>10^5$ cm${}^{-3}$) in High Latitude Planck Galactic Cold Clumps
• Cloud G074.11+00.11: a stellar cluster in formation