Survey of ortho-H${}_2$D${}^{+}$ in high-mass star-forming regions

Abstract

(Abridged) We present a large sample of o-H${}_2$D${}^{+}$ observations in high-mass star-forming regions and discuss possible empirical correlations with relevant physical quantities to assess its role as a chronometer of star-forming regions through different evolutionary stages. APEX observations of the ground-state transition of o-H${}_2$D${}^{+}$ were analysed in a sample of massive clumps selected from ATLASGAL at different evolutionary stages. Column densities and beam-averaged abundances of o-H${}_2$D${}^{+}$ with respect to H${}_2$, $X$(o-H${}_2$D${}^{+}$), were obtained by modelling the spectra under the assumption of local thermodynamic equilibrium. We detect 16 sources in o-H${}_2$D${}^{+}$ and find clear correlations between $X$(o-H${}_2$D${}^{+}$) and the clump bolometric luminosity and the dust temperature, while only a mild correlation is found with the CO-depletion factor. In addition, we see a clear correlation with the luminosity-to-mass ratio, which is known to trace the evolution of the star formation process. This would indicate that the deuterated forms of H${}_3^{+}$ are more abundant in the early stages of the star formation process and that deuteration is influenced by the time evolution of the clumps. In this respect, our findings would suggest that the $X$(o-H${}_2$D${}^{+}$) abundance is mainly affected by the thermal changes rather than density changes in the gas. We have employed these findings together with observations of H${}^{13}$CO${}^{+}$, DCO${}^{+}$, and C${}^{17}$O to provide an estimate of the cosmic-ray ionisation rate in a sub-sample of eight clumps based on recent analytical work. Our study presents the largest sample of o-H${}_2$D${}^{+}$ in star-forming regions to date. The results confirm that the deuteration process is strongly affected by temperature and suggests that o-H${}_2$D${}^{+}$ can be considered a reliable chemical clock during the star formation processes, as proved by its strong temporal dependence.

18 pages, 8 figures and 6 tables. To appear in A&A

References in corpus (19)

• Cold Dark Clouds: The Initial Conditions for Star Formation
• ATLASGAL --- properties of a complete sample of Galactic clumps
• Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate
• ATLASGAL --- towards a complete sample of massive star forming clumps
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• ATLASGAL-selected massive clumps in the inner Galaxy: I. CO depletion and isotopic ratios
• ATLASGAL-selected massive clumps in the inner Galaxy III. Dust Continuum Characterization of an Evolutionary Sample
• ATLASGAL - Kinematic distances and the dense gas mass distribution of the inner Galaxy
• The Distribution of Ortho-H_2D+(1_1,0 - 1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores
• Galactic interstellar 18O/17O ratios - a radial gradient?
• The Hi-GAL catalogue of dusty filamentary structures in the Galactic Plane
• A systematic TMRT observational study of Galactic ${}^{12}$C/${}^{13}$C ratios from Formaldehyde
• Revealing H2D+ depletion and compact structure in starless and protostellar cores with ALMA
• Simultaneous Determination of the Cosmic Ray Ionization Rate and Fractional Ionization in DR21(OH)
• Detection of 6 K gas in Ophiuchus D
• The 3D structure of CO depletion in high-mass prestellar regions
• A timeline for massive star-forming regions via combined observation of o-H${}_2$D${}^{+}$ and N${}_2$D${}^{+}$
• Detection of H2D+ in a massive prestellar core in Orion B
• APEX observations of ortho-H${}_2$D${}^{+}$ towards dense cores in the Orion B9 filament

Cited by in corpus (20)

• Cosmic rays in molecular clouds probed by H${}_2$ rovibrational lines -- Perspectives for the James Webb Space Telescope
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• The cosmic-ray ionisation rate in the pre-stellar core L1544
• Establishing the evolutionary timescales of the massive star formation process through chemistry
• The core population and kinematics of a massive clump at early stages: an ALMA view
• Identification of prestellar cores in high-mass star forming clumps via ${\mathrm{H}}_2{\mathrm{D}}^{+}$ observations with ALMA
• First ALMA maps of cosmic ray ionisation rate in high-mass star-forming regions
• 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
• Abundance ratios of OH/CO and HCO+/CO as probes of the cosmic ray ionization rate in diffuse clouds
• The double signature of local cosmic-ray acceleration in star-forming regions
• Parsec-scale cosmic-ray ionisation rate in Orion
• Cosmic-ray ionisation rate in low-mass cores: the role of the environment
• The impact of cosmic ray heating on the cooling of the low-metallicity interstellar medium
• Impact of cosmic-ray propagation on the chemistry and ionisation fraction of dark clouds
• Binary Formation in a 100 $\mu$m-dark Massive Core
• CO Depletion in Infrared Dark Clouds
• Synthetic observations using POLARIS: an application to simulations of massive prestellar cores
• The Cygnus Allscale Survey of Chemistry and Dynamical Environments: CASCADE III. The large scale distribution of DCO+, DNC and DCN in the DR21 filament
• Gauging the Impact of Cosmic Ray Feedback on the Stellar Initial Mass Function