J/MNRAS/451/3089 Young clumps embedded in IRDC (Traficante+, 2015)
The initial conditions of stellar protocluster formation.
II. A catalogue of starless and protostellar clumps embedded in IRDCs in the
Galactic longitude range 15<l<55.
Traficante A., Fuller G.A., Peretto N., Pineda J.E., Molinari S.
<Mon. Not. R. Astron. Soc. 451, 3089 (2015)>
=2015MNRAS.451.3089T 2015MNRAS.451.3089T
ADC_Keywords: Galaxies, photometry ; Infrared sources; Protostars ;
Stars, early-type
Keywords: catalogues - stars: formation - stars: massive - ISM: clouds -
Galaxy: stellar content - infrared: stars
Abstract:
We present a catalogue of starless and protostellar clumps associated
with infrared dark clouds (IRDCs) in a 40 degrees wide region of the
inner Galactic plane (|b|≤1). We have extracted the far-infrared
(FIR) counterparts of 3493 IRDCs with known distance in the Galactic
longitude range 15≤l≤55 and searched for the young clumps using
Herschel infrared Galactic plane survey, the survey of the Galactic
plane carried out with the Herschel satellite. Each clump is
identified as a compact source detected at 160, 250 and 350um. The
clumps have been classified as protostellar or starless, based on
their emission (or lack of emission) at 70um. We identify 1723
clumps, 1056 (61%) of which are protostellar and 667 (39%) starless.
These clumps are found within 764 different IRDCs, 375 (49%) of which
are only associated with protostellar clumps, 178 (23%) only with
starless clumps, and 211 (28%) with both categories of clumps. The
clumps have a median mass of ∼250M☉ and range up to >104M☉
in mass and up to 105L☉ in luminosity. The mass-radius
distribution shows that almost 30% of the starless clumps identified
in this survey could form high-mass stars; however these massive
clumps are confined in only 4% of the IRDCs. Assuming a minimum mass
surface density threshold for the formation of high-mass stars, the
comparison of the numbers of massive starless clumps and those already
containing embedded sources suggests an upper limit lifetime for the
starless phase of ∼105yr for clumps with a mass M>500M☉.
Description:
Photometric parameters for 667 starless clumps (sources identified at
160um with a counterpart at 250 and 350um) and 1056 protostellar
clumps (sources identified at 160um with a counterpart at 70, 250 and
350um).
Photometric parameters obtained with Hyper photometry code
(2015A&A...574A.119T 2015A&A...574A.119T). The photometry is corrected for aperture and
colour corrections. The parameter list is the standard Hyper output
(see description below).
SED fit parameters for 650 starless clumps and 1034 protostellar
clumps (all clumps with good SED fitting: Chi2<10, Temperature<40K.
See the paper for details)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
pre_ph.dat 119 2001 Starless clumps photometric parameters
pro_ph.dat 119 4224 Protostellar clumps photometric parameters
pre_sed.dat 77 649 Starless clumps SED fitting parameters
pro_sed.dat 77 1030 Protostellar clumps SED fitting parameters
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Byte-by-byte Description of file: pre_ph.dat pro_ph.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Parent IRDC name
14- 15 I2 --- Seq [1/32] Hyper id. number relative to each cloud
17- 19 I3 um Band [70/350] Herschel wavelength
21- 30 F10.3 MJy/sr Ssurf [-614/388350] Peak flux in MJy/sr
32- 37 F6.3 Jy Speak [-0.3/94] Peak flux in Jy in Band
39- 46 F8.3 Jy Sint [0.003/3727] Integrated flux in Band
48- 54 F7.3 Jy e_Sint [0.032/1607] Error on integrated flux (1)
56- 61 F6.3 Jy Sbg [0.002/10.7] Background (bg) emission
63- 67 F5.3 Jy Sres [0.002/10] Residual emission after background
subtraction (2)
69 I1 --- P [1/4] Polynomial order for bg estimation (3)
71- 75 F5.2 arcsec fw.min [18/37] Minor axis of the clump (4)
77- 81 F5.2 arcsec fw.max [18/37] Major axis of the clump (4)
83- 88 F6.2 deg PA [0/270] Position angle
90- 91 I2 --- Fit [-2/0] Fit convergence status, 0=ok (5)
93-100 F8.4 deg RAdeg Right ascension (J2000.0)
102-109 F8.4 deg DEdeg Declination (J2000.0)
111-115 F5.2 arcsec Dist [0/14] Distance from the reference centroid
(source position at 160µm)
117 I1 --- Nd [0/6] Number of deblended sources
119 I1 --- Nc [1/6] Number of clustered sources
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Note (1): Residual r.m.s. per pixel integrated across the same number
of pixels of the source.
Note (2): Residual r.m.s. around the clump after background subtraction.
Note (3): polynomial order from 1 to 4, automatically chosen by Hyper.
Note (4): equivalent to the minimum and maximum FWHM of the 2d-Gaussian fit.
Note (5): 2d-Gaussian fit convergence status as follows:
0 = regular convergence
-1 = the source fit was too elongated (axes ratio ≥2.5)
-2 = fitting routine did not converge
-------------------------------------------------------------------------------
Byte-by-byte Description of file: pre_sed.dat pro_sed.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Parent IRDC name
14- 15 I2 --- Seq [1/32] Hyper id. number relative to each cloud
17- 24 F8.2 Msun Mass [0.1/15558] Clump mass
26- 33 F8.2 Lsun Lum [0.08/58882] Clump luminosity
35- 38 F4.2 pc Rad [0.02/2.61] Clump radius (1)
40- 44 F5.2 K T [7.7/40] Clump temperature
46- 50 F5.2 K e_T [0.3/12.4] Temperature error (2)
52- 55 F4.2 --- chi2 [0/10] Reduced χ2 of the SED fit
57- 61 F5.2 kpc Dist [0.1/17] Distance of parent IRDC
63- 69 F7.3 deg RAdeg Right ascension (J2000.0) of the 160um centroid
71- 77 F7.3 deg DEdeg Declination (J2000.0) of the 160um centroid
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Note (1): Radius estimated as geometrical mean of 2d-Gaussian FWHMs.
Note (2): Automatically estimated from the MPFIFUN routine.
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Acknowledgements:
Alessio Traficante, alessio.traficante(at)gmail.com
References:
Peretto & Fuller, Paper I 2009A&A...505..405P 2009A&A...505..405P, Cat. J/A+A/505/405
Traficante et al., 2015A&A...574A.119T 2015A&A...574A.119T,
Hyper: Hybrid photometry and extraction routine
(End) Patricia Vannier [CDS] 25-Jun-2015