The JCMT Gould Belt Survey: A First Look at Southern Orion A with SCUBA-2

Abstract

We present the JCMT Gould Belt Survey's first look results of the southern extent of the Orion A Molecular Cloud ($\delta \le -5:31:27.5$). Employing a two-step structure identification process, we construct individual catalogues for large-scale regions of significant emission labelled as islands and smaller-scale subregions called fragments using the 850 $\mu$m continuum maps obtained using SCUBA-2. We calculate object masses, sizes, column densities, and concentrations. We discuss fragmentation in terms of a Jeans instability analysis and highlight interesting structures as candidates for follow-up studies. Furthermore, we associate the detected emission with young stellar objects (YSOs) identified by Spitzer and Herschel. We find that although the population of active star-forming regions contains a wide variety of sizes and morphologies, there is a strong positive correlation between the concentration of an emission region and its calculated Jeans instability. There are, however, a number of highly unstable subregions in dense areas of the map that show no evidence of star formation. We find that only $\sim$72\% of the YSOs defined as Class 0+I and flat-spectrum protostars coincide with dense 850 $\mu$m emission structures (column densities $>3.7\times 10^{21}{\mathrm{cm}}^{-2}$). The remaining 28\% of these objects, which are expected to be embedded in dust and gas, may be misclassified. Finally, we suggest that there is an evolution in the velocity dispersion of young stellar objects such that sources which are more evolved are associated with higher velocities.

31 Pages, 19 Figures, Accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS)

References in corpus (25)

• Astrophysics Source Code Library
• Structural Analysis of Molecular Clouds: Dendrograms
• The SCUBA Legacy Catalogue: Continuum Objects Detected by SCUBA
• SCUBA-2: iterative map-making with the Sub-Millimetre User Reduction Facility
• The Effects of Radiative Transfer on Low-Mass Star Formation
• The Large and Small Scale Structures of Dust in the Star-Forming Perseus Molecular Cloud
• A SCUBA survey of Orion, the low-mass end of the core mass function
• Herschel-Planck dust optical-depth and column-density maps: I. Method description and results for Orion
• The James Clerk Maxwell Telescope Legacy Survey of Nearby Star-forming Regions in the Gould Belt
• Dynamics of Dense Cores in the Perseus Molecular Cloud
• FellWalker - a Clump Identification Algorithm
• Current Star Formation in the Ophiuchus and Perseus Molecular Clouds: Constraints and Comparisons from Unbiased Submillimeter and Mid-Infrared Surveys. II
• NICEST, a near-infrared color excess method tailored for small-scale structures
• Current Star Formation in the Perseus Molecular Cloud: Constraints from Unbiased Submillimeter and Mid-Infrared Surveys
• The Perils of Clumpfind: The Mass Spectrum of Sub-structures in Molecular Clouds
• The chemistry and spatial distribution of small hydrocarbons in UV-irradiated molecular clouds: the Orion Bar PDR
• The nature of the Class I population in Ophiuchus as revealed through gas and dust mapping
• IN-SYNC II: Virial Stars from Sub-Virial Cores -- The Velocity Dispersion of Embedded Pre-Main-Sequence Stars in NGC 1333
• Large Area Mapping at 850 Microns. V. Analysis of the Clump Distribution in the Orion A South Molecular Cloud
• IN-SYNC I: Homogeneous Stellar Parameters from High Resolution APOGEE Spectra for Thousands of Pre-main Sequence Star
• IRAM-30m large scale survey of ${}^{12}$CO(2-1) and ${}^{13}$CO(2-1) emission in the Orion molecular cloud
• Massive Quiescent Cores in Orion. -- II. Core Mass Function
• The JCMT Gould Belt Survey: Evidence for radiative heating in Serpens MWC 297 and its influence on local star formation
• Star Formation in the Orion Nebula I: Stellar Content
• The JCMT Gould Belt Survey: SCUBA-2 observations of circumstellar disks in L 1495

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• Intensity-Corrected Herschel Observations of Nearby Isolated Low-Mass Clouds
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• ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): Evidence for a Molecular Jet Launched at an Unprecedented Early Phase of Protostellar evolution
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• Alignment of dense molecular core morphology and velocity gradients with ambient magnetic fields
• Observational evidence for rotational desorption of Complex Molecules by radiative torques from Orion BN/KL
• TIMES I: a Systematic Observation in Multiple Molecular Lines Toward the Orion A and Ophiuchus Clouds
• W51North: A protocluster emerging out of a thermally inhibited fragmenting cloud
• The origin of dust polarization in the Orion Bar
• Spatial Statistics in Star Forming Regions: Testing the Limits of Randomness
• Interplay between Young Stars and Molecular Clouds in the Ophiuchus Star-forming Complex
• Spatial Statistics in Star Forming Regions: Is Star Formation Driven By Column Density Alone?
• Emergence of high-mass stars in complex fiber networks (EMERGE) III. Fiber networks in Orion
• The factors that influence protostellar multiplicity I: Gas temperature, density, and mass in Perseus with Nobeyama
• The JCMT Gould Belt Survey Complete Core Catalogue: Core mass function variations between nearby molecular clouds
• Submillimetre Transient Science in the Next Decade: EAO Submillimetre Futures White Paper Series, 2019
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