J/A+A/559/A79 IRDC APEX/SABOCA observations (Ragan+, 2013)
APEX/SABOCA observations of small-scale structure of infrared-dark clouds.
I. Early evolutionary stages of star-forming cores.
Ragan S.E., Henning T., Beuther H.
<Astron. Astrophys., 559, A79-79 (2013)>
=2013A&A...559A..79R 2013A&A...559A..79R
ADC_Keywords: Infrared sources; Molecular clouds; Millimetric/submm sources
Keywords: catalogs - stars: formation - ISM: structure - submillimeter: ISM
Abstract:
Infrared-dark clouds (IRDCs) harbor the early phases of cluster and
high-mass star formation and are comprised of cold (∼20K), dense
(n>104cm-3) gas. The spectral energy distribution (SED) of IRDCs
is dominated by the far-infrared and millimeter wavelength regime, and
our initial Herschel study examined IRDCs at the peak of the SED with
high angular resolution. Here we present a follow-up study using the
SABOCA instrument on APEX which delivers 7.8" angular resolution at
350µm, matching the resolution we achieved with Herschel/PACS, and
allowing us to characterize substructure on ∼0.1pc scales. Our sample
of 11 nearby IRDCs are a mix of filamentary and clumpy morphologies,
and the filamentary clouds show significant hierarchical structure,
while the clumpy IRDCs exhibit little hierarchical structure. All
IRDCs, regardless of morphology, have about 14% of their total mass in
small scale core-like structures which roughly follow a trend of
constant volume density over all size scales. Out of the 89
protostellar cores we identified in this sample with Herschel, we
recover 40 of the brightest and re-fit their SEDs and find their
properties agree fairly well with our previous estimates (∼19K). We
detect a new population of "cold cores" which have no 70µm
counterpart, but are 100 and 160µm-bright, with colder temperatures
(∼16K). This latter population, along with SABOCA-only detections,
are predominantly low-mass objects, but their evolutionary diagnostics
are consistent with the earliest starless or prestellar phase of cores
in IRDCs.
Description:
We surveyed our sample at the Atacama Pathfinder Experiment (APEX)
12-m telescope using the Submillimetre APEX Bolometer Camera. Our
pilot study to map IRDC 011.11-0.12 was completed in 2010 (project
M085-0029), and the remaining ten sources were observed in April and
August 2011 (project M087-0021).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 11 Target and observation summary
tableb1.dat 79 135 Leaves from dendrogram decomposition of SABOCA
350um image
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See also:
J/ApJ/706/727 : Distance and mass of Infrared Dark Clouds (Marshall+, 2009)
J/A+A/547/A49 : Herschel EPoS: high-mass overview (Ragan+, 2012)
J/A+A/561/A148 : Mass Distribution of Infrared Dark Clouds (Gomez+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- IRDC IRDC (Infra-Red Dark Cloud) name
16 A1 --- n_IRDC [*] *: filamentary IRDCs
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 27 F4.1 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 37 I2 arcsec DEs Declination (J2000)
39- 41 F3.1 kpc Dist [2.3/5] Distance
43- 45 F3.1 kpc E_Dist Error on Dist (upper value)
47- 49 F3.1 kpc e_Dist Error on Dist (lower value)
51- 55 I5 Msun Mass Mass above N∼1021cm-2 from ATLASGAL survey
(see Ragan et al., 2012, Cat. J/A+A/547/A49)
57 I1 arcsec Size1 Map size
58 A1 --- --- [x]
59- 60 I2 arcsec Size2 Map size
62- 71 A10 "date" ObsDate Observation date
73- 77 I5 s Tint [3780/21000] Integration time
79- 82 F4.2 Jy rms rms (in Jy/beam)
84- 91 E8.3 cm-2 NH2sens H2 column density sensitivity
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- IRDC IRDC name
17- 18 I2 --- Leaf [1/42] Leaf number within the IRDC
19 A1 --- n_Leaf [c] Leaf overlaps multiple cores (1)
21- 22 I2 h RAh Right ascension (J2000)
24- 25 I2 min RAm Right ascension (J2000)
27- 30 F4.1 s RAs Right ascension (J2000)
32 A1 --- DE- Declination sign (J2000)
33- 34 I2 deg DEd Declination (J2000)
36- 37 I2 arcmin DEm Declination (J2000)
39- 40 I2 arcsec DEs Declination (J2000)
42- 46 F5.1 Jy Stot Integrated flux contribution from dendrogram
leaf (with parent branch/trunk flux subtracted)
at 350um
48- 50 F3.1 Jy Spar Parent branch/trunk flux (in Jy/beam)
52- 59 E8.3 cm-2 NH2 Mean H2 column density (2)
61- 64 F4.2 pc Reff Effective radius
66- 69 I4 Msun M20K Mass calculated from 350um data with T(dust)=20K
71- 74 I4 Msun M Mass calculated from 350um data
76- 79 A4 --- Com Comments
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Note (1): Leaf overlaps with multiple Herschel cores (see Sect. 4.5 for
details).
Note (2): Assuming Tdust of the best fit (see Table 3) or (if no Herschel
counterpart) the upper limit temperature.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 07-Mar-2014