COLD DUST IN HOT REGIONS

We mapped five massive star-forming regions with the SCUBA-2 camera on the James Clerk Maxwell Telescope. Temperature and column density maps are obtained from the SCUBA-2 450 and 850 μm images. Most of the dense clumps we find have central temperatures below 20 K, with some as cold as 8 K, suggesting that they have no internal heating due to the presence of embedded protostars. This is surprising, because at the high densities inferred from these images and at these low temperatures such clumps should be unstable, collapsing to form stars and generating internal heating. The column densities at the clump centers exceed 1023 cm−2, and the derived peak visual extinction values are from 25 to 500 mag for β = 1.5–2.5, indicating highly opaque centers. The observed cloud gas masses range from ∼10 to 103 M☉. The outer regions of the clumps follow an r−2.36  ±  0.35 density distribution, and this power-law structure is observed outside of typically 104 AU. All these findings suggest that these clumps are high-mass starless clumps and most likely contain high-mass starless cores.

[1]  M. Juvela,et al.  The degeneracy between dust colour temperature and spectral index - Comparison of methods for estimating the β(T) relation , 2013, 1305.2130.

[2]  A. Duarte-Cabral,et al.  THE HERSCHEL AND JCMT GOULD BELT SURVEYS: CONSTRAINING DUST PROPERTIES IN THE PERSEUS B1 CLUMP WITH PACS, SPIRE, AND SCUBA-2 , 2013, 1303.1529.

[3]  Per Friberg,et al.  Scuba-2: On-sky calibration using submillimetre standard sources , 2013, 1301.3773.

[4]  Douglas Scott,et al.  Scuba-2: Iterative map-making with the sub-millimetre user reduction facility , 2013, 1301.3652.

[5]  P. A. R. Ade,et al.  SCUBA-2: the 10 000 pixel bolometer camera on the James Clerk Maxwell Telescope , 2013, 1301.3650.

[6]  A. Bolatto,et al.  The CO-to-H2 Conversion Factor , 2013, 1301.3498.

[7]  J. Richer,et al.  The JCMT Gould Belt Survey: SCUBA-2 observations of radiative feedback in NGC 1333 , 2012, 1210.5094.

[8]  L. Testi,et al.  ALMA OBSERVATIONS OF ρ-Oph 102: GRAIN GROWTH AND MOLECULAR GAS IN THE DISK AROUND A YOUNG BROWN DWARF , 2012, 1211.6743.

[9]  CONNECTING THE DOTS: ANALYZING SYNTHETIC OBSERVATIONS OF STAR-FORMING CLUMPS IN MOLECULAR CLOUDS , 2012, 1207.5535.

[10]  D. Wilner,et al.  Grain growth signatures in the protoplanetary discs of Chamaeleon and Lupus , 2012, 1207.0260.

[11]  A. Whitworth,et al.  Isolated starless cores in infrared dark clouds in the Hi-GAL survey , 2012, 1205.1647.

[12]  D. Johnstone,et al.  Molecular line contamination in the SCUBA-2 450 and 850 μm continuum data , 2012, 1204.6180.

[13]  A. Goodman,et al.  DUST SPECTRAL ENERGY DISTRIBUTIONS IN THE ERA OF HERSCHEL AND PLANCK: A HIERARCHICAL BAYESIAN-FITTING TECHNIQUE , 2012, 1203.0025.

[14]  P. Andre',et al.  The Herschel view of the on-going star formation in the Vela-C molecular cloud , 2012, 1202.1413.

[15]  S. Bontemps,et al.  Search for starless clumps in the ATLASGAL survey , 2012, 1201.4732.

[16]  M. Fich,et al.  STUDY OF MOLECULAR CLOUDS ASSOCIATED WITH H ii REGIONS , 2011, 1102.0287.

[17]  P. McGehee,et al.  Galactic cold cores: II. Herschel study of the extended dust emission around the first: Planck detections , 2011, 1101.3003.

[18]  N. Evans,et al.  OBSERVATIONAL CONSTRAINTS ON SUBMILLIMETER DUST OPACITY , 2010, 1012.3488.

[19]  M. Halpern,et al.  THE BALLOON-BORNE LARGE APERTURE SUBMILLIMETER TELESCOPE (BLAST) 2005: A 10 deg2 SURVEY OF STAR FORMATION IN CYGNUS X , 2010, 1009.2972.

[20]  P. Bernardis,et al.  Variations of the spectral index of dust emissivity from Hi-GAL observations of the Galactic plane , 2010, 1009.2779.

[21]  Douglas Scott,et al.  JCMT Telescope Control System upgrades for SCUBA-2 , 2010, Astronomical Telescopes + Instrumentation.

[22]  M. Sauvage,et al.  Initial highlights of the HOBYS key program , the Herschel imaging survey of OB young stellar objects Journal Item , 2018 .

[23]  S. Ott,et al.  Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy , 2010, 1005.5331.

[24]  R. Emery,et al.  The physical properties of the dust in the RCW 120 HII region as seen by Herschel , 2010, 1005.1565.

[25]  R. Neri,et al.  Dust properties of protoplanetary disks in the Taurus-Auriga star forming region from millimeter wavelengths , 2009, 0912.3356.

[26]  J. Foster,et al.  THE DUST EMISSIVITY SPECTRAL INDEX IN THE STARLESS CORE TMC-1C , 2009, 0911.0892.

[27]  A. Bolatto,et al.  THE STRUCTURE OF A LOW-METALLICITY GIANT MOLECULAR CLOUD COMPLEX , 2009, 0907.2240.

[28]  A. Goodman,et al.  THE EFFECT OF LINE-OF-SIGHT TEMPERATURE VARIATION AND NOISE ON DUST CONTINUUM OBSERVATIONS , 2009, 0902.3477.

[29]  L. Mundy,et al.  GRAIN GROWTH AND DENSITY DISTRIBUTION OF THE YOUNGEST PROTOSTELLAR SYSTEMS , 2009, 0902.2008.

[30]  A. Goodman,et al.  THE EFFECT OF NOISE ON THE DUST TEMPERATURE–SPECTRAL INDEX CORRELATION , 2009, 0902.0636.

[31]  G. Fazio,et al.  Spitzer Observations of the Massive Star-forming Complex S254-S258: Structure and Evolution , 2008, 0803.3358.

[32]  J. Aumont,et al.  Submillimetre point sources from the Archeops experiment : very cold clumps in the Galactic plane , 2008, 0801.4502.

[33]  C. Adami,et al.  Revised distances of Northern HII regions , 2007 .

[34]  W. Welch,et al.  A Case Study of Low-Mass Star Formation , 2007, 0706.2206.

[35]  A. Whitworth,et al.  The dust temperatures of the pre-stellar cores in the ρ Oph main cloud and in other star-forming regions: consequences for the core mass function , 2007, 0705.2941.

[36]  J. Bally,et al.  Large-Area Mapping at 850 μm. V. Analysis of the Clump Distribution in the Orion A South Molecular Cloud , 2005, astro-ph/0512382.

[37]  D. Johnstone,et al.  The effect of a strong external radiation field on protostellar envelopes in Orion , 2005, astro-ph/0512314.

[38]  P. Schilke,et al.  High-Mass Starless Cores , 2005, astro-ph/0508421.

[39]  J. Rawlings,et al.  Modeling the Physical Structure of the Low-Density Pre-Protostellar Core Lynds 1498 , 2005, astro-ph/0505171.

[40]  G. Fuller,et al.  The circumstellar environments of high-mass protostellar objects. II. Dust continuum models , 2005 .

[41]  A. Goodman,et al.  Density and Temperature Structure of TMC-1C from 450 and 850 Micron Maps , 2005, astro-ph/0502024.

[42]  K. Rice,et al.  Protostars and Planets V , 2005 .

[43]  Itziar Aretxaga,et al.  The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: Calibration and Targeted Sources , 2004, SPIE Astronomical Telescopes + Instrumentation.

[44]  L. Dunne,et al.  Revised masses of dust and gas of SCUBA Local Universe Survey far-infrared bright galaxies based on a recent CO survey , 2004, astro-ph/0401602.

[45]  B. Draine.  INTERSTELLAR DUST GRAINS , 2003, astro-ph/0304489.

[46]  J. Bernard,et al.  Inverse temperature dependence of the dust submillimeter spectral index , 2003, astro-ph/0310091.

[47]  C. Kramer,et al.  Dust properties of the dark cloud IC 5146 - Submillimeter and NIR imaging , 2002, astro-ph/0212265.

[48]  M. Walmsley,et al.  The structure and stability of molecular cloud cores in external radiation fields , 2002, astro-ph/0208416.

[49]  Y. Shirley,et al.  The Physical Conditions for Massive Star Formation: Dust Continuum Maps and Modeling , 2002, astro-ph/0207322.

[50]  E. Dishoeck,et al.  Physical structure and CO abundance of low-mass protostellar envelopes , 2002, astro-ph/0205068.

[51]  H Germany,et al.  Systematic Molecular Differentiation in Starless Cores , 2001, astro-ph/0112487.

[52]  T. K. Sridharan,et al.  High-Mass Proto-Stellar Candidates - II : Density structure from dust continuum and CS emission , 2001, astro-ph/0110370.

[53]  D. Johnstone,et al.  Large Area Mapping at 850 Microns. III. Analysis of the Clump Distribution in the Orion B Molecular Cloud , 2001 .

[54]  P. Goldsmith.  Molecular Depletion and Thermal Balance in Dark Cloud Cores , 2000 .

[55]  C. McKee,et al.  Efficiencies of Low-Mass Star and Star Cluster Formation , 2000, astro-ph/0007383.

[56]  S. Ghosh,et al.  Distribution of Cold Dust in Orion A and B , 2000, astro-ph/0007349.

[57]  L. Mundy,et al.  Tracing the Mass during Low-Mass Star Formation. II. Modeling the Submillimeter Emission from Preprotostellar Cores , 2000, astro-ph/0006183.

[58]  P. Papadopoulos,et al.  Gas and Dust in NGC 7469: Submillimeter Imaging and CO J = 3-2 , 2000, astro-ph/0002277.

[59]  G. Blake,et al.  Structure and Evolution of the Envelopes of Deeply Embedded Massive Young Stars , 2000, astro-ph/0001527.

[60]  F. Motte,et al.  The initial conditions of isolated star formation — III. Millimetre continuum mapping of pre-stellar cores , 1999 .

[61]  E. Serabyn,et al.  350 Micron Continuum Imaging of the Orion A Molecular Cloud with the Submillimeter High Angular Resolution Camera , 1998 .

[62]  Y. Kuan,et al.  Three millimeter continuum studies of Sagittarius B2 , 1996 .

[63]  P. Andre',et al.  A submillimetre continuum survey of pre-protostellar cores , 1994 .

[64]  F. Adams.  Asymptotic theory for the spatial distribution of protostellar emission , 1991 .

[65]  Steven V. W. Beckwith,et al.  Particle Emissivity in Circumstellar Disks , 1991 .

[66]  F. Schloerb,et al.  A CO AND FAR-INFRARED STUDY OF THE S254-S258 REGION , 1989 .

[67]  J. Black,et al.  The photodissociation and chemistry of interstellar CO , 1988 .

[68]  J. Mathis.  Interstellar dust and extinction , 1987 .

[69]  M. Peimbert,et al.  Star Forming Regions , 1987 .

[70]  E. Dwek,et al.  Molecular Clouds and Star Formation in the Inner Galaxy: A Comparison of CO, H ii, and Far-Infrared Surveys , 1986 .

[71]  H. M. Lee,et al.  Optical properties of interstellar graphite and silicate grains , 1984 .

[72]  R. Dickman,et al.  The ratio of carbon monoxide to molecular hydrogen in interstellar dark clouds , 1978 .

[73]  F. Shu.  Self-similar collapse of isothermal spheres and star formation. , 1977 .

[74]  P. Pişmiş,et al.  Study of a triple emission nebula in Orion , 1976 .