J/ApJ/817/167 JCMT Gould Belt Survey: dense cores in Orion B (Kirk+, 2016)
The JCMT Gould Belt Survey: a first look at dense cores in Orion B.
Kirk H., Di Francesco J., Johnstone D., Duarte-Cabral A., Sadavoy S.,
Hatchell J., Mottram J.C., Buckle J., Berry D.S., Broekhoven-Fiene H.,
Currie M.J., Fich M., Jenness T., Nutter D., Pattle K., Pineda J.E.,
Quinn C., Salji C., Tisi S., Hogerheijde M.R., Ward-Thompson D.,
Bastien P., Bresnahan D., Butner H., Chen M., Chrysostomou A., Coude S.,
Davis C.J., Drabek-Maunder E., Fiege J., Friberg P., Friesen R.,
Fuller G.A., Graves S., Greaves J., Gregson J., Holland W., Joncas G.,
Kirk J.M., Knee L.B.G., Mairs S., Marsh K., Matthews B.C.,
Moriarty-Schieven G., Mowat C., Rawlings J., Richer J., Robertson D.,
Rosolowsky E., Rumble D., Thomas H., Tothill N., Viti S., White G.J.,
Wouterloot J., Yates J., Zhu M.
<Astrophys. J., 817, 167 (2016)>
=2016ApJ...817..167K 2016ApJ...817..167K (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Millimetric/submm sources ; YSOs ; Surveys
Keywords: dust, extinction; stars: formation; submillimeter: ISM
Abstract:
We present a first look at the SCUBA-2 observations of three
sub-regions of the Orion B molecular cloud: LDN 1622, NGC 2023/2024,
and NGC 2068/2071, from the JCMT Gould Belt Legacy Survey. We identify
29, 564, and 322 dense cores in L1622, NGC 2023/2024, and NGC
2068/2071 respectively, using the SCUBA-2 850µm map, and present
their basic properties, including their peak fluxes, total fluxes, and
sizes, and an estimate of the corresponding 450µm peak fluxes and
total fluxes, using the FellWalker source extraction algorithm.
Assuming a constant temperature of 20K, the starless dense cores have
a mass function similar to that found in previous dense core analyses,
with a Salpeter-like slope at the high-mass end. The majority of cores
appear stable to gravitational collapse when considering only thermal
pressure; indeed, most of the cores which have masses above the
thermal Jeans mass are already associated with at least one protostar.
At higher cloud column densities, above 1-2x1023/cm2, most of the
mass is found within dense cores, while at lower cloud column
densities, below 1x1023/cm2, this fraction drops to 10% or lower.
Overall, the fraction of dense cores associated with a protostar is
quite small (<8%), but becomes larger for the densest and most
centrally concentrated cores. NGC 2023/2024 and NGC 2068/2071 appear
to be on the path to forming a significant number of stars in the
future, while L1622 has little additional mass in dense cores to form
many new stars.
Description:
Orion B was observed with SCUBA-2 at 850 and 450um as part of the JCMT
Gould Belt Survey (Ward-Thompson et al. 2007PASP..119..855W 2007PASP..119..855W). Three
separate regions were observed: the areas around L1622, NGC 2023/2024,
and NGC 2068/2071, as illustrated in Figure 1. The SCUBA-2
observations were obtained between 2012 February and 2014 November
with some initial science verification data taken in 2011 October and
November.
Portions of the NGC 2023/2024 and NGC 2068/2071 regions were also
observed by the Gould Belt Survey (GBS) in 12CO(3-2) with HARP.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 121 915 *Dense cores identified with FellWalker
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Note on table2.dat: Our identification of dense cores, which was based on
Starlink's FellWalker algorithm (Berry 2015A&C....10...22B 2015A&C....10...22B) is described in
Appendix A.
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See also:
J/MNRAS/449/1769 : Orion A North prestellar core properties (Salji+, 2015)
J/A+A/566/A45 : Orion optical-depth and column-density maps (Lombardi+, 2014)
J/ApJ/790/49 : Gould's Belt VLA survey. III. Orion region (Kounkel+, 2014)
J/ApJ/767/36 : APEX observations of HOPS protostars (Stutz+, 2013)
J/A+A/538/A137 : Orion B9 dense cores maps (Miettinen+, 2012)
J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSO catalog (Megeath+, 2012)
J/ApJ/710/1247 : Dense cores in Gould Belt clouds (Sadavoy+, 2010)
J/ApJ/691/1560 : Dense core survey in the Orion B cloud (Ikeda+, 2009)
J/ApJS/175/277 : Submillimeter-Continuum SCUBA detections (Di Francesco+, 2008)
J/MNRAS/374/1413 : SCUBA survey of Orion (Nutter+, 2007)
J/ApJ/668/1042 : Dense cores in Perseus molecular cloud (Kirk+, 2007)
J/ApJ/639/259 : Sub-mm clumps in Orion B South mol. cloud (Johnstone+, 2006)
J/A+A/440/151 : Observations at 850um in Perseus clusters (Hatchell+, 2005)
J/ApJ/559/307 : Sub-mm mapping in Orion B molecular cloud (Johnstone+, 2001)
J/A+A/372/L41 : NGC 2068/2071 protoclusters (Motte+, 2001)
http://www.herschel.fr/cea/gouldbelt/en : Herschel Goud Belt survey home page
http://www3.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/en/jcmt : JCMT Science Archive
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- MJLSG Source Name (JHHMMSS.s+DDMMSS)
18- 27 A10 --- Region Region surveyed
29- 31 I3 --- Seq [1/564] Source Index number in Region
33 I1 h RAh [5] Hour of Right Ascension (J2000) (1)
35- 36 I2 min RAm [39/55] Minute of Right Ascension (J2000) (1)
38- 42 F5.2 s RAs Second of Right Ascension (J2000) (1)
44 A1 --- DE- Sign of the Declination (J2000) (1)
45- 46 I2 deg DEd Degree of Declination (J2000) (1)
48- 49 I2 arcmin DEm Arcminute of Declination (J2000) (1)
51- 54 F4.1 arcsec DEs Arcsecond of Declination (J2000) (1)
56- 61 F6.3 Jy/beam F850Pk [0.02/11.5] Peak 850µm Flux (2)
63- 69 F7.3 Jy F850Tot [0.01/120] Total SCUBA-2 850µm Flux (2)
71- 75 F5.3 pc Reff [0.02/0.3] Effective Radius measured
from 850µm image
77- 82 F6.3 Jy/beam F450Pk [0.1/45] Peak 450µm Flux (3)
84- 91 F8.3 Jy F450Tot [-0.3/1117] Total SCUBA-2 450µm Flux (3)
93 A1 --- YSO [Y/N] YSO Flag (4)
95- 98 F4.2 --- COCov [0.06/1]?=0 Fraction of dense core footprint
where CO observations exist
100-105 F6.3 Jy/beam F850Pk2 [0.03/11.4]?=-1 Peak 850µm Flux corrected
for CO emission, where available
107-113 F7.3 Jy F850Tot2 [0.005/118]?=-1 Total 850µm Flux corrected
for CO emission, where available
115-121 F7.3 Jy F850Tot3 [-0.3/104] Total 850µm Flux corrected
for constant background emission
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Note (1): Position of peak emission in the dense core.
Note (2): Peak flux, total flux, and effective radius of the dense cores, as
measured at 850µm. The effective beamsize at 850µm is
14.6arcsec.
Note (3): Peak flux and total flux at 450µm within the dense core boundaries
defined on the 850µm image. The total flux may be negative in
regions without a detected 450µm signal. The effective beamsize at
450µm is 9.8arcsec.
Note (4): Is the dense core associated with a protostar in Spitzer,
Megeath et al. (2012, J/AJ/144/192) or Herschel,
Stutz et al. (2013, J/ApJ/767/36).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Apr-2016