A NIKA view of two star-forming infrared dark clouds: Dust emissivity variations and mass concentration

Abstract

The thermal emission of dust grains is a powerful tool for probing cold, dense regions of molecular gas in the ISM, and so constraining dust properties is key to obtaining accurate measurements of dust mass and temperature. By placing constraints on the dust emissivity spectral index, beta, towards two star-forming infrared dark clouds, SDC18.888 and SDC24.489, we evaluate the role of mass concentration in the associated star-formation activity. We exploit the simultaneous 1.2mm and 2.0mm imaging capability of NIKA on the IRAM 30m telescope to construct maps of beta for both clouds, and by incorporating Herschel observations, we create H2 column density maps with 13" resolution. While we find no significant systematic radial variations around the most massive clumps in either cloud on >0.1 pc scales, their mean beta values are significantly different, with beta = 2.07 +/- 0.09 (rand) +/- 0.25 (syst) for SDC18.888 and beta = 1.71 +/- 0.09 (rand) +/- 0.25 (syst) for SDC24.489. These differences could be a consequence of the very different environments in which both clouds lie, and we suggest that the proximity of SDC18.888 to the W39 HII region may raise beta on scales of 1 pc. We also find that the mass in SDC24.489 is more centrally concentrated and circularly symmetric than in SDC18.888, and is consistent with a scenario in which spherical globally-collapsing clouds concentrate a higher fraction of their mass into a single core than elongated clouds that will more easily fragment, distributing their mass into many cores. We demonstrate that beta variations towards interstellar clouds can be robustly constrained with high-SNR NIKA observations, providing more accurate estimates of their masses. The methods presented here will be applied to the Galactic Star Formation with NIKA2 (GASTON) large programme, extending our analysis to a statistically significant sample of star-forming clouds.

arXiv commentAbstract abridged. 18 pages, 16 figures, 2 tables. Accepted for publication in Astronomy & Astrophysics

References in corpus (58)

• Astropy: A Community Python Package for Astronomy
• The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory
• The Herschel-SPIRE instrument and its in-flight performance
• GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870 microns
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Hi-GAL: the Herschel infrared Galactic Plane Survey
• Herschel view of the Taurus B211/3 filament and striations: Evidence of filamentary growth?
• Structural Analysis of Molecular Clouds: Dendrograms
• A Catalog of Extended Green Objects (EGOs) in the GLIMPSE Survey: A new sample of massive young stellar object outflow candidates
• Common-Resolution Convolution Kernels for Space- and Ground-Based Telescopes
• Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey
• The initial conditions of stellar protocluster formation. I. A catalogue of Spitzer dark clouds
• Identifying the Low Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores
• The Large APEX Bolometer Camera LABOCA
• Hi-GAL, the Herschel infrared Galactic Plane Survey: photometric maps and compact source catalogues. First data release for Inner Milky Way: +68°> l > -70°
• The Behavior of the Aromatic Features in M101 HII Regions: Evidence for Dust Processing
• How Many Infrared Dark Clouds can form Massive Stars and Clusters?
• ATLASGAL --- towards a complete sample of massive star forming clumps
• Planck Early Results: Thermal dust in Nearby Molecular Clouds
• In-flight calibration of the Herschel-SPIRE instrument
• A Catalog of MSX Infrared Dark Cloud Candidates
• The Ubiquity of Micrometer-Sized Dust Grains in the Dense Interstellar Medium
• Inverse temperature dependence of the dust submillimeter spectral index
• The Herschel Exploitation of Local Galaxy Andromeda (HELGA) II: Dust and Gas in Andromeda
• A dual-band millimeter-wave kinetic inductance camera for the IRAM 30-meter telescope
• The NIKA2 large field-of-view millimeter continuum camera for the 30-m IRAM telescope
• The Mass-Size Relation from Clouds to Cores. II. Solar Neighborhood Clouds
• The Effect of Noise on the Dust Temperature - Spectral Index Correlation
• The JCMT Gould Belt Survey: First results from the SCUBA-2 observations of the Ophiuchus molecular cloud and a virial analysis of its prestellar core population
• The data reduction pipeline for the Hi-GAL survey
• The Herschel and JCMT Gould Belt Surveys: Constraining Dust Properties in the Perseus B1 Clump with PACS, SPIRE, and SCUBA-2
• Submillimetre point sources from the Archeops experiment: Very Cold Clumps in the Galactic Plane
• NIKA: A millimeter-wave kinetic inductance camera
• Direct evidence of dust growth in L183 from MIR light scattering
• Variation in dust properties in a dense filament of the Taurus molecular complex (L1506)
• The Mass-Size Relation from Clouds to Cores. I. A new Probe of Structure in Molecular Clouds
• Performance and calibration of the NIKA camera at the IRAM 30 m telescope
• The ATLASGAL survey: distribution of cold dust in the Galactic plane. Combination with Planck data
• Far-infrared dust opacity and visible extinction in the Polaris Flare
• Galactic cold cores VI. Dust opacity spectral index
• First observation of the thermal Sunyaev-Zel'dovich effect with kinetic inductance detectors
• Perturbation growth in accreting filaments
• Pressure distribution of the high-redshift cluster of galaxies CL J1226.9+3332 with NIKA
• Probing changes of dust properties along a chain of solar-type prestellar and protostellar cores in Taurus with NIKA
• Using CO line ratios to trace the physical properties of molecular clouds
• The Initial Conditions of Stellar Protocluster Formation: III. The Herschel counterparts of the Spitzer Dark Cloud catalogue
• The JCMT Gould Belt Survey: Evidence for Dust Grain Evolution in Perseus Star-forming Clumps
• Dust emission from young outflows: the case of L1157
• Resolving the Vela C ridge with P-ArTeMiS and Herschel
• 350 Micron Observations of Local Luminous Infrared Galaxies and the Temperature Dependence of the Emissivity Index
• Dust Emissivity in the Star-Forming Filament OMC 2/3
• Non-parametric deprojection of NIKA SZ observations: Pressure distribution in the Planck-discovered cluster PSZ1 G045.85+57.71
• YSO jets in the Galactic Plane from UWISH2: I - MHO catalogue for Serpens and Aquila
• Search for grain growth towards the center of L1544
• POKER: Estimating the power spectrum of diffuse emission with complex masks and at high angular resolution
• Massive Star Formation at the Periphery of the Evolved Giant HII Region W 39

Cited by in corpus (14)

• Calibration and Performance of the NIKA2 camera at the IRAM 30-meter Telescope
• An ALMA study of hub-filament systems I. On the clump mass concentration within the most massive cores
• New insights in the HII region G18.88-0.49: hub-filament system and accreting filaments
• GASTON: Galactic Star Formation with NIKA2. Evidence for the mass growth of star-forming clumps
• ALMA observations of the Extended Green Object G19.01$-$0.03: I. A Keplerian disc in a massive protostellar system
• The dynamic centres of infrared-dark clouds and the formation of cores
• Chemical Differentiation around Five Massive Protostars Revealed by ALMA -Carbon-Chain Species, Oxygen-/Nitrogen-Bearing Complex Organic Molecules-
• The Interstellar Dust Emission Spectrum, Going beyond the single temperature greybody
• NOEMA complementarity with NIKA2
• The Quest for the Missing Dust: I -- Restoring Large Scale Emission in Herschel Maps of Local Group Galaxies
• ALMA discovery of a dual dense probably rotating outflow from a massive young stellar object G18.88MME
• GASTON: Galactic Star Formation with NIKA2: A new population of cold massive sources discovered
• NIKA2 observations of starless cores in Taurus and Perseus
• Dust Temperature Profiles in Dense Cores Associated With Massive Star-Forming Regions