J/A+A/540/A113 Starless clumps in ATLASGAL (Tackenberg+, 2012)
Search for starless clumps in the ATLASGAL survey .
Tackenberg J., Beuther H., Henning T., Schuller F., Wienen M., Motte F.,
Wyrowski F., Bontemps S., Bronfman L., Menten K., Testi L., Lefloch B.
<Astron. Astrophys. 540, A113 (2012)>
=2012A&A...540A.113T 2012A&A...540A.113T
ADC_Keywords: Molecular clouds
Keywords: ISM: clouds - stars: formation - surveys - stars: massive -
stars: distances - Galaxy: fundamental parameters
Abstract:
Understanding massive star formation requires comprehensive knowledge
about the initial conditions of this process. The cradles of massive
stars are believed to be located in dense and massive molecular
clumps.
In this study, we present an unbiased sample of the earliest stages of
massive star formation across 20deg2 of the sky. Within the region
10°<l<20° and |b|<1°, we search the ATLASGAL survey at
870um for dense gas condensations. These clumps are carefully examined
for indications of ongoing star formation using YSOs from the GLIMPSE
source catalog as well as sources in the 24um MIPSGAL images, to
search for starless clumps. We calculate the column densities as well
as the kinematic distances and masses for sources where the vlsr is
known from spectroscopic observations.
Within the given region, we identify 210 starless clumps with peak
column densities >1023cm-2. In particular, we identify potential
starless clumps on the other side of the Galaxy. The sizes of the
clumps range between 0.1pc and 3pc with masses between a few tens of
M☉ up to several ten thousands of M☉.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 95 210 Properties of starless clumps
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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- 4 I4 --- ID Global identifier
6- 12 F7.4 deg GLON Galactic longitude
14- 20 F7.4 deg GLAT Galactic latitude
22- 29 F8.4 deg RAdeg Right ascension in decimal degrees (J2000)
31- 38 F8.4 deg DEdeg Declination in decimal degrees (J2000)
40- 43 F4.2 Jy Fpeak Peak flux at 870um
45- 46 I2 arcsec Rad CLUMPFIND effective radius
48- 52 F5.2 Jy Fint Integrated flux over clump at 870um (Jy/beam)
54- 57 F4.1 km/s VNH3 ?=- NH3 velocity (1)
59 I1 --- f_VNH3 [0/1] 1 = direct NH3 observation (1)
61- 65 F5.1 km/s VHCO+ ?=- HCO+ velocity (2)
67 I1 --- f_VHCO+ [0/1] 1 = HCO+ observation (2)
69- 72 F4.1 kpc Dnear ?=- Kinematic near distance (4)
74- 77 F4.1 kpc Dfar ?=- Kinematic far distance (4)
79- 82 F4.2 10+23cm-2 NHpeak Peak column density (5)
84- 87 I4 Msun Mnear ?=- Mass calculated using the near distance
89- 93 I5 Msun Mfar ?=- Mass calculated using the far distance
95 I1 --- f_Mfar [0/1] 1 = use of near distance
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Note (1): Origin of the NH3 velocity:
* When f_VNH3=1, velocities are taken from Wienen et al. (submitted);
* when f_VNH3=0, velocity has been adopted from neighboring clumps
Note (2): Origin of the HCO+ velocity:
* when f_VHCO+=1, velocities are taken from Schlingman et al.
2011ApJS..195...14S 2011ApJS..195...14S;
* when f_VHCO+=0, velocity has been adopted from neighboring clumps
Note (4): Kinematic distances have been calculated using a Galactic
rotation curve from Reid et al. (2009ApJ...700..137R 2009ApJ...700..137R). If present, NH3
velocities have been used. Negative near distance solutions indicate
that the observed velocities for given line of sights place the
objects in the outer Galaxy. Thus, only the far solution is physical.
Note (5): Column densities and masses have been calculated using parameters
as described in the paper.
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Acknowledgements:
Jochen Tackenberg, tackenberg(at)mpia.de
(End) J. Tackenberg [Max-Planck-Inst. for Astron.], P. Vannier [CDS] 27-Jan-2012