Identification of prestellar cores in high-mass star forming clumps via ${\mathrm{H}}_2{\mathrm{D}}^{+}$ observations with ALMA

Abstract

Context. The different theoretical models concerning the formation of high-mass stars make distinct predictions regarding their progenitors, i.e. the high-mass prestellar cores. However, so far no conclusive observation of such objects has been made. Aims. We aim to study the very early stages of high-mass star formation in two infrared-dark, massive clumps, to identify the core population that they harbour. Methods. We obtained ALMA observations of continuum emission at 0.8mm and of the ortho-${\mathrm{H}}_2{\mathrm{D}}^{+}$ transition at 372GHz towards the two clumps. We use the SCIMES algorithm to identify cores in the position-position-velocity space, finding 16 cores. We model their observed spectra in the LTE approximation, deriving the centroid velocity, linewidth, and column density maps. We also study the correlation between the continuum and molecular data, which in general do not present the same structure. Results. We report for the first time the detection of ortho-${\mathrm{H}}_2{\mathrm{D}}^{+}$ in high-mass star-forming regions performed with an interferometer. The molecular emission shows narrow and subsonic lines, suggesting that locally the temperature of the gas is less than 10K. From the continuum emission we estimate the cores' total masses, and compare them with the respective virial masses. We also compute the volume density values, which are found to be higher than $10^6\mathrm{c}{\mathrm{m}}^{-3}$. Conclusions. Our data confirm that ortho-${\mathrm{H}}_2{\mathrm{D}}^{+}$ is an ideal tracer of cold and dense gas. Interestingly, almost all the ${\mathrm{H}}_2{\mathrm{D}}^{+}$-identified cores are less massive than 13M_sun , with the exception of one core in AG354. Furthermore, most of them are subvirial and larger than their Jeans masses. These results are difficult to explain in the context of the turbulent accretion models, which predict massive and virialised prestellar cores.

arXiv commentAccepted for publications in A&A

References in corpus (77)

• GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
• Toward Understanding Massive Star Formation
• The Formation of Massive Stars from Turbulent Cores
• ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870 microns
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Structural Analysis of Molecular Clouds: Dendrograms
• Multi-Scale CLEAN deconvolution of radio synthesis images
• High-Mass Star and Massive Cluster Formation in the Milky Way
• Our astrochemical heritage
• The Birth Environment of the Solar System
• Tracing the Mass during Low-Mass Star Formation. II. Modelling the Submillimeter Emission from Pre-Protostellar Cores
• Star formation through gravitational collapse and competitive accretion
• ATLASGAL --- properties of a complete sample of Galactic clumps
• Bias-free Measurement of Giant Molecular Cloud Properties
• Observing the gas temperature drop in the high-density nucleus of L 1544
• How Many Infrared Dark Clouds can form Massive Stars and Clusters?
• Complete Depletion in prestellar cores
• Abundant H2D+ in the pre-stellar core L1544
• Magnetic Fields and Massive Star Formation
• The ALMA Survey of 70 $\mu$m dark High-mass clumps in Early Stages (ASHES). I. Pilot Survey: Clump Fragmentation
• The Simultaneous Formation of Massive Stars and Stellar Clusters
• The Origin of Massive Stars: The Inertial-Inflow Model
• Weeds: a CLASS extension for the analysis of millimeter and sub-millimeter spectral surveys
• The Degree of CO Depletion in Pre-stellar Cores
• The Dynamics of Massive Starless Cores with ALMA
• The dust temperature distribution in prestellar cores
• Survey of ortho-H2D+(1_{1,0}-1_{1,1}) in dense cloud cores
• Depletion and low gas temperature in the L183 prestellar core : the N2H+ - N2D+ tool
• The N2D+/N2H+ ratio as an evolutionary tracer of Class 0 protostars
• The dynamical properties of dense filaments in the infrared dark cloud G035.39-00.33
• A Massive Prestellar Clump Hosting no High-Mass Cores
• Deuteration as an evolutionary tracer in massive-star formation
• ATLASGAL-selected massive clumps in the inner Galaxy: I. CO depletion and isotopic ratios
• Graph-based interpretation of the Molecular Interstellar Medium Segmentation
• ATLASGAL-selected massive clumps in the inner Galaxy III. Dust Continuum Characterization of an Evolutionary Sample
• DR 21(OH): a highly fragmented, magnetized, turbulent dense core
• The earliest phases of high-mass star formation, as seen in NGC 6334 by \emph{Herschel}
• Infall Signatures in a Prestellar Core embedded in the High-Mass 70 $\mu$m Dark IRDC G331.372-00.116
• ATLASGAL-selected massive clumps in the inner Galaxy: V. Temperature structure and evolution
• An Ordered Bipolar Outflow from a Massive Early-Stage Core
• Quiescent Dense Gas in Protostellar Clusters: the Ophiuchus A Core
• High sensitivity maps of molecular ions in L1544: I. Deuteration of N2H+ and HCO+ and first evidence of N2D+ depletion
• The central 1000 AU of a pre-stellar core revealed with ALMA. I. 1.3 mm continuum observations
• HD depletion in starless cores
• Parameterizing the interstellar dust temperature
• Review of Zeeman Effect Observations of Regions of Star Formation
• 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
• The Deuterium Fraction in Massive Starless Cores and Dynamical Implications
• Revealing H2D+ depletion and compact structure in starless and protostellar cores with ALMA
• A Hunt for Massive Starless Cores
• Formation of Massive Protostellar Clusters -- Observations of Massive 70 $\mu$m Dark Molecular Clouds
• G11.92-0.61-MM2: A Bonafide Massive Prestellar Core?
• Massive and low-mass protostars in massive "starless" cores
• Detection of a high-mass prestellar core candidate in W43-MM1
• Gas and dust temperature in pre-stellar cores revisited: New limits on cosmic-ray ionization rate
• Magnetic fields in the early stages of massive star formation as revealed by ALMA
• ALMA-IRDC: Dense gas mass distribution from cloud to core scales
• Survey of ortho-H${}_2$D${}^{+}$ in high-mass star-forming regions
• Zooming in to Massive Star Birth
• Detection of 6 K gas in Ophiuchus D
• Molecular analysis of a high-mass prestellar core candidate in W43-MM1
• H2D+ in the high mass star-forming Region Cygnus-X
• On the size of the CO-depletion radius in the IRDC G351.77-0.51
• The chemical structure of young high-mass star-forming clumps: (II) parsec-scale CO depletion and deuterium fraction of $\mathrm{HC}{\mathrm{O}}^{+}$
• The 3D structure of CO depletion in high-mass prestellar regions
• Subsonic islands within a high-mass star-forming IRDC
• Cradle(s) of the Sun
• A timeline for massive star-forming regions via combined observation of o-H${}_2$D${}^{+}$ and N${}_2$D${}^{+}$
• The chemical structure of young high-mass star-forming clumps: (I) Deuteration
• The highly variable time evolution of star-forming cores identified with dendrograms
• Detection of H2D+ in a massive prestellar core in Orion B
• Fast deuterium fractionation in magnetized and turbulent filaments
• APEX observations of ortho-H${}_2$D${}^{+}$ towards dense cores in the Orion B9 filament
• Probing the initial conditions of high-mass star formation -- IV. Gas dynamics and NH${}_2$D chemistry in high-mass precluster and protocluster clumps
• Structure, Dynamics and Deuterium Fractionation of Massive Pre-Stellar Cores
• Deuterium Chemodynamics of Massive Pre-Stellar Cores
• An X-ray View of Two Infrared Dark Clouds G034.43+00.24 and G035.39-00.33

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• The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VI. The core-scale CO-depletion
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• Variations of the HCO${}^{+}$, HCN, HNC, N${}_2$H${}^{+}$ and NH${}_3$ deuterium fractionation in high-mass star-forming regions
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• 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
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