J/MNRAS/422/1071 Cores in IR Dark Clouds for 300≤l≤330 (Wilcock+, 2012)
Cores in infrared dark clouds (IRDCs) seen in the Hi-GAL survey between
l=300° and 330°.
Wilcock L.A., Ward-Thompson D., Kirk J.M., Stamatellos D., Whitworth A.,
Elia D., Fuller G.A., Di Giorgio A., Griffin M.J., Molinari S., Martin P.,
Mottram J.C., Peretto N., Pestalozzi M., Schisano E., Plume R., Smith H.A.,
Thompson M.A.
<Mon. Not. R. Astron. Soc., 422, 1071-1082 (2012)>
=2012MNRAS.422.1071W 2012MNRAS.422.1071W
ADC_Keywords: Infrared sources ; Molecular clouds
Keywords: stars: formation
Abstract:
We have used data taken as part of the Herschel infrared Galactic
Plane survey (Hi-GAL) to study 3171 infrared dark cloud (IRDC)
candidates that were identified in the mid-IR (8um) by Spitzer (we
refer to these as 'Spitzer-dark' regions). They all lie in the range
l=300-330° and |b|≤1°. Of these, only 1205 were seen in
emission in the far-IR (250-500um) by Herschel (we call these
'Herschel-bright' clouds). It is predicted that a dense cloud will not
only be seen in absorption in the mid-IR, but will also be seen in
emission in the far-IR at the longest Herschel wavebands (250-500um).
If a region is dark at all wavelengths throughout the mid-IR and
far-IR, then it is most likely to be simply a region of lower
background IR emission (a 'hole in the sky'). Hence, it appears that
previous surveys, based on Spitzer and other mid-IR data alone, may
have overestimated the total IRDC population by a factor of ∼2. This
has implications for estimates of the star formation rate in IRDCs in
the Galaxy. We studied the 1205 Herschel-bright IRDCs at 250um and
found that 972 of them had at least one clearly defined 250-um peak,
indicating that they contained one or more dense cores. Of these, 653
(67 per cent) contained an 8-um point source somewhere within the
cloud, 149 (15 per cent) contained a 24-um point source but no 8-um
source and 170 (18 per cent) contained no 24- or 8-um point sources.
We use these statistics to make inferences about the lifetimes of the
various evolutionary stages of IRDCs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 54 1204 The 1204 IRDCs which were found to be
Herschel-bright
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See also:
J/A+A/505/405 : A catalogue of Spitzer dark clouds (Peretto+, 2009)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- IRDC IRDC name (LLL.lll-B.bbb) (1)
14 A1 --- m_IRDC [ABC] Multiplicity index on IRDC
16- 21 F6.2 deg RAdeg Right ascension (J2000)
23- 28 F6.2 deg DEdeg Declination (J2000)
30- 32 A3 --- 8um [Yes/No ] contains an 8µm source ?
34- 36 A3 --- 24um [Yes/No ] contains an 24µm source ?
38- 54 A17 --- Com Additional comments (2)
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Note (1): as in Perreto and Fuller, 2009, Cat. J/A+A/505/405,
in Simbad
Note (2): Additional information about the cloud, including whether it
contains a visible core and whether it is isolated at 160 and 500um.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 28-Dec-2012