J/ApJ/779/79 Galactic CHaMP. II. Dense gas clumps. (Ma+, 2013)
The Galactic Census of High- and Medium-mass Protostars.
II. Luminosities and evolutionary states of a complete sample of dense gas
clumps.
Ma B., Tan J.C., Barnes P.J.
<Astrophys. J., 779, 79 (2013)>
=2013ApJ...779...79M 2013ApJ...779...79M
ADC_Keywords: Millimetric/submm sources ; Surveys ; Velocity dispersion
Keywords: dust, extinction; stars: formation; stars: pre-main sequence; surveys
Abstract:
The Census of High- and Medium-mass Protostars (CHaMP) is the first
large-scale (280°<l<300°, -4°<b<2°), unbiased,
subparsec resolution survey of Galactic molecular clumps and their
embedded stars. Barnes et al. (Paper I, 2011, J/ApJS/196/12) presented
the source catalog of ∼300 clumps based on HCO+(1-0) emission, used
to estimate masses M. Here we use archival midinfrared-to-millimeter
continuum data to construct spectral energy distributions. Fitting
two-temperature gray-body models, we derive bolometric luminosities,
L. We find that the clumps have 10≲L/L☉≲106.5 and
0.1≲L/M/[L☉/M☉]≲103, consistent with a clump
population spanning a range of instantaneous star-formation
efficiencies from 0 to ∼50%. We thus expect L/M to be a useful,
strongly varying indicator of clump evolution during the star cluster
formation process.
Description:
A total of 303 dense gas clumps have been detected using the
HCO+(1-0) line in the CHaMP survey (Paper I, Barnes et al. 2011,
J/ApJS/196/12). In this article we have derived the SED for these
clumps using Spitzer, MSX, and IRAS data.
The Midcourse Space Experiment (MSX) was launched in 1996 April. It
conducted a Galactic plane survey (0<l<360°, |b|<5°), which
covers all the CHaMP clumps. The four MSX band wavelengths are
centered at 8.28, 12.13, 14.65, and 21.3um. The best image resolution
is ∼18" in the 8.28um band, with positional accuracy of about 2".
Calibrated images of the Galactic plane were obtained from the online
MSX image server at the IPAC website.
The IRAS performed an all-sky survey at 12, 25, 60, and 100um. The
nominal resolution is about 4' at 60um. High Resolution Image
Restoration (HIRES) uses the maximum correlation method to produce
higher resolution images, better than 1' at 60um. Sources chosen for
processing with HIRES were processed at all four IRAS bands with 20
iterations.
The Spitzer InfraRed Array Camera (IRAC) is a four-channel camera that
provides simultaneous 5.2"x5.2" images at 3.6, 4.5, 5.8, and 8um with
an angular resolution of about 2" at 8um. We searched the Spitzer
archive at IPAC. Most of these data are from two large survey
programs: PID 189 (Churchwell, E., "The SIRTF Galactic Plane Survey")
and PID 40791 (Majewski, S., "Galactic Structure and Star Formation in
Vela-Carina").
Hill et al. (2005, J/MNRAS/363/405) carried out a 1.2mm continuum
emission survey toward 131 star-forming complexes using the Swedish
ESO Submillimetre Telescope (SEST) IMaging Bolometer Array (SIMBA).
Hill et al. list the 1.2mm flux for 404 sources, 15 of which are in
our sample.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 59 303 Primary physical properties of HCO+(1-0) clumps
table3.dat 74 303 Secondary physical properties of HCO+(1-0) clumps
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See also:
V/98 : MSX Infrared Astrometric Catalog (Egan+ 1996)
J/ApJS/196/12 : Paper I. First results from Mopra HCO+ maps (Barnes+, 2011)
J/ApJ/723/492 : GRS molecular clouds physical properties (Roman-Duval+, 2010)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/A+A/481/345 : SED evolution in massive YSOs (Molinari+, 2008)
J/MNRAS/363/405 : SIMBA observations of cold cores (Hill+, 2005)
J/A+A/426/97 : SIMBA survey. 1.2-mm/IRAS sources (Faundez+, 2004)
J/ApJ/566/945 : Massive star forming regions at 1.2mm (Beuther+, 2002)
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- BYF The BYF number from Paper I
(Barnes et al. 2011, J/ApJS/196/12)
4 A1 --- m_BYF Sub-clump letter from Paper I
6- 6 A1 --- f_BYF [*] Uncertain measurement of L (1)
8- 11 F4.2 [Msun] logM [1.1/3.9] Log of the mass; from Paper I
(Barnes et al. 2011, J/ApJS/196/12)
13- 16 F4.1 K Tc [14/47] Colder component temperature (2)
18- 23 F6.2 [mW/m2] logF [-12/-5] Log of colder component bolometric
flux; erg/s/cm2 (2)
25- 29 F5.2 [Lsun] logLIR [-0.1/6.3] Log of IR luminosity (2)
31- 35 F5.2 [Sun] logL/M [-2/3.5] Log of IR luminosity to mass ratio (2)
37- 40 F4.1 K Tcb [10/50] Colder component temperature (3)
42- 47 F6.2 [mW/m2] logFb [-12/-5] Log of colder component bolometric
flux; erg/s/cm2 (3)
49- 53 F5.2 [Lsun] logLIRb [-0.9/6.2] Log of IR luminosity (3)
55- 59 F5.2 [Sun] logL/Mb [-3/3.4] Log of IR luminosity to mass ratio (3)
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Note (1): the asterisk (*) indicates a clump with an uncertain measurement
of L due to IRAS 100 micron background subtraction (see Fig. 2b).
Note (2): Derived using the non-background subtracted method.
Note (3): Derived using the background subtracted method.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- BYF The BYF number
4 A1 --- m_BYF Sub-clump letter
6- 11 F6.2 [mW/m2] logFw [-11.5/-5.7] Log of warm component flux;
erg/s/cm2
13- 18 F6.2 [mW/m2] logFwb [-12.2/-5.7] Log of warm component flux;
(background-subtracted; in erg/s/cm2)
20- 25 F6.2 [mW/m2] logFIR [-14.1/-6.7]? Log of IRAC bands flux;
erg/s/cm2
27- 32 F6.2 [mW/m2] logFIRb [-13.1/-6.7]? Log of IRAC bands flux;
(background-subtracted; in erg/s/cm2)
34- 38 F5.2 [mW/m2/sr] logIIR [-7.5/-0.8]? Log of IRAC intensity;
erg/s/cm2/sr
40- 44 F5.2 [mW/m2/sr] logIIRb [-6.5/-0.6]? Log of IRAC intensity
(background-subtracted; in erg/s/cm2/sr)
46- 48 I3 K Tbol [70/259] Bolometric temperature
50- 52 I3 K Tbolb [55/499] Bolometric temperature
(background-subtracted)
54- 58 F5.3 g/cm2 Sigma [0.005/0.6] Mass surface density Σ
60- 63 F4.2 km/s sig.v [0.2/4.2] Velocity dispersion σV
65- 68 F4.1 --- alpha [1/54.4] Virial parameter αvir (4)
70- 74 F5.2 [K.km/s/pc2] logLHCO [-0.5/2.1] Log of HCO+(1-0) line
luminosity
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Note (4): The virial parameter, αvir=5σ2R/(GM) (Bertoldi &
McKee 1992ApJ...395..140B 1992ApJ...395..140B), is proportional to the ratio of a clump's
kinetic and gravitational energies; see section 5.2.
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Nomenclature note:
Clumps are <[BYF2011] NNNa> in Simbad.
History:
From electronic version of the journal
References:
Barnes et al. Paper I. 2011ApJS..196...12B 2011ApJS..196...12B Cat. J/ApJS/196/12
Barnes et al. Paper III. 2016ApJ...831...67B 2016ApJ...831...67B Cat. J/ApJ/831/67
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 29-Apr-2015