J/A+A/515/A42 Catalog of high extinction clouds (Rygl+, 2010)
Initial stages of massive star formation in high infrared extinction clouds.
I. Physiscal parameters.
Rygl K.L.J., Wyrowsky F., Schuller F., Menten K.M.
<Astron. Astrophys. 515, A42 (2010)>
=2010A&A...515A..42R 2010A&A...515A..42R
ADC_Keywords: Molecular clouds ; Interstellar medium ; Infrared sources ;
Millimetric/submm sources ; Radio lines ; Extinction
Keywords: dust, extinction - ISM: clouds - ISM: structure - stars: formation -
radio lines: ISM - submillimeter: ISM
Abstract:
The earliest phases of massive star formation are found in cold and
dense infrared dark clouds (IRDCs). Since the detection method of
IRDCs is very sensitive to the local properties of the background
emission, we present here an alternative method to search for high
column density in the Galactic plane by using infrared extinction
maps. We find clouds between 1 and 5kpc, of which many were missed by
previous surveys. By studying the physical conditions of a subsample
of these clouds, we aim at a better understanding of the initial
conditions of massive star formation. We made extinction maps of the
Galactic plane based on the 3.6-4.5 microns color excess between the
two shortest wavelength Spitzer IRAC bands, reaching to visual
extinctions of ∼100mag and column densities of 9x1022cm-2. From
this we compiled a new sample of cold and compact high extinction
clouds. We used the MAMBO array at the IRAM 30m telescope to study the
morphology, masses, and densities of the clouds and the dense clumps
within them. The latter were followed up by pointed ammonia
observations with the 100m Effelsberg telescope to determine
rotational temperatures and kinematic distances. Extinction maps of
the Galactic plane trace large scale structures such as the spiral
arms. The extinction method probes lower column densities,
N(H_2)∼4x1022cm-2, than the 1.2mm continuum, which reaches up to
N(H_2)∼3x1023cm-2 but is less sensitive to large scale structures.
The 1.2mm emission maps reveal that the high extinction clouds contain
extended cold dust emission, from filamentary structures to still
diffuse clouds. Most of the clouds are dark in 24 microns, but several
show already signs of star formation via maser emission or bright
infrared sources, suggesting that the high extinction clouds contain a
variety of evolutionary stages. The observations suggest an
evolutionary scheme from dark, cold and diffuse clouds, to clouds with
a stronger 1.2mm peak and to finally clouds with many strong 1.2mm
peaks, which are also warmer, more turbulent, and already have some
star formation signposts.
Description:
We made maps of the 3.6-4.5 microns color excess between the two
shortest wavelength Spitzer IRAC bands (Fazio et al.
2004ApJS..154...10F 2004ApJS..154...10F). These can be converted to infrared extinction
maps using the interstellar extinction law of Indebetouw et al.
(2005ApJ...619..931I 2005ApJ...619..931I): one magnitude of 3.6-4.5 microns color excess
corresponds to 81.8 magnitudes in visual extinction (see Eq. 2 in our
article). Our maps cover -60 degree to 60 degree in Galactic longitude
except for 1 degree around the Galactic center and have a resolution
of 108". The color excess maps are available as fits files belonging
to Fig. 1. All the unknown compact high extinction regions with a
color excess above 0.25mag, which were not known as HII regions or
high-mass protostellar objects, were catalogued in Table 1 as high
extinction clouds (HECs). For a sample of 25 high extinction clouds in
the first Galactic quadrant we observed the dust continuum emission at
1.2mm using the MAMBO-2 bolometer. These observations have a much
higher angular resolution of 11", allowing to probe the clouds at
subparsec scales and study the clumps with them.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 44 226 Catalog of high extinction clouds (HECs) with
the peak color excess, E<(3.6-4.5)>
table2.dat 71 31 Properties of the high extinction clouds
table3.dat 78 44 Positions (J2000) and fluxes of the clumps from
the 1.2mm continuum data
table4.dat 59 13 Positions (J2000) and determined properties
toward the positions without clumps
table5.dat 86 51 Observed ammonia parameters with uncertainties
from hyperfine and Gaussian fits with CLASS
table7.dat 69 44 Properties of the clumps derived from NH3 and
the 1.2mm continuum
fig1.dat 25 120 List of FITS files containing the 3.6-4.5um color
excess maps for the inner part of the Galaxy
fig5.dat 34 25 List of FITS files containing the 1.2mm dust
continuum maps
ce/* . 120 FITS files containing the 3.6-4.5um color excess maps
mambo/* . 25 FITS files containing the 1.2mm dust continuum maps
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See also:
V/112 : Catalog of Star-Forming Regions in the Galaxy (Avedisova, 2002)
J/ApJS/95/457 : IRAS images of nearby dark clouds (Wood+ 1994)
J/ApJ/639/227 : MSX IRDC candidate catalog (Simon+, 2006)
J/ApJ/641/389 : Millimetric observations of IRDC cores (Rathborne+, 2006)
J/ApJ/651/L125 : Water masers associated with IR dark cloud cores (Wang+, 2006
J/ApJ/653/1325 : Galactic distribution of infrared dark clouds (Simon+, 2006)
J/ApJS/166/567 : Radio Molecular lines in infrared dark clouds (Ragan+, 2006)
J/ApJ/706/727 : Distance and mass of Infrared Dark Clouds (Marshall+, 2009)
J/A+A/499/149 : 1.2mm maps of southern Infrared Dark Clouds (Vasyunina+, 2009)
J/A+A/505/405 : A catalogue of Spitzer dark clouds (Peretto+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [HEC]
5- 17 A13 --- HEC High extinction cloud name (GLLL.ll+BB.bb)
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 29 F4.1 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 39 I2 arcsec DEs Declination (J2000)
41- 44 F4.2 mag E(ir) 3.6-4.5µm color excess
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- HEC High extinction cloud name (GLLL.ll+BB.bb)
14 A1 --- m_HEC [A-D] Subgrouping of cloud based on the
kinematic distance
16- 18 I3 arcsec Rad ? Radius of the cloud in arcsec (1)
20- 23 F4.2 pc Rad2 ? Radius of the cloud in parsec (1)
25- 26 I2 mag <Av> ? Average visual extinction derived from the
extinction maps
28- 30 F3.1 10+22cm-2 NH2 ? Average hydrogen column density derived from
the extinction maps
32- 36 F5.2 Jy S1.2 ? Integrated 1.2mm flux
38- 41 I4 Msun Mext ? Cloud mass derived from the extinction maps
43- 50 F8.3 Msun M1.2 ? Cloud mass derived from the 1.2mm
52- 55 I4 mJy Clump ? Peak of the 1.2mm emission in the clump in
units of mJy/beam
57- 59 I3 mJy Cloud ? Mean 1.2mm emission of the cloud without the
clumps
61- 71 A11 --- Class Class of HEC: diffuse, peaked or multiply p.
-------------------------------------------------------------------------------
Note (1): Radius is the square root of the area divided by π. For the
conversion to parsecs we use the kinematic distance based on the
NH3(1,1) line.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- HEC High extinction cloud name (GLLL.ll+BB.bb)
14 A1 --- m_HEC [A-D] Subgrouping of cloud based on the
kinematic distance
16- 18 A3 --- mm Millimeter clump number
20- 21 I2 h RAh Hour of right ascension (J2000)
23- 24 I2 min RAm Minute of right ascension (J2000)
26- 29 F4.1 s RAs Second of right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Degree of declination (J2000)
35- 36 I2 arcmin DEm Arcminute of declination (J2000)
38- 39 I2 arcsec DEs Arcsecond of declination (J2000)
41- 43 I3 mJy F1.2 1.2mm peak flux in mJy/beam
45- 46 I2 mJy e_F1.2 F1.2 uncertainty in mJy/beam
48- 51 I4 mJy S1.2 Integrated 1.2mm flux
53- 60 F8.3 mJy S1.2d Integrated 1.2mm flux within 0.25pc diameter
62- 65 F4.1 arcsec a Clump major axis
67- 70 F4.1 arcsec b Clump minor axis
72- 76 F5.1 deg PA [-90/+90] Position angle
78 A1 --- H2O [-/+] Water maser detection (+: detection,
-: non-detection and empty: not observed)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- HEC High extinction cloud name (GLLL.ll+BB.bb)
14 A1 --- m_HEC [A-D] Subgrouping of cloud based on the
kinematic distance
16- 18 A3 --- mm Millimeter clump number
20- 21 I2 h RAh Hour of right ascension (J2000)
23- 24 I2 min RAm Minute of right ascension (J2000)
26- 29 F4.1 s RAs Second of right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Degree of declination (J2000)
35- 36 I2 arcmin DEm Arcminute of declination (J2000)
38- 39 I2 arcsec DEs Arcsecond of declination (J2000)
41- 43 F3.1 kpc dkin ? Kinematic distance
45- 47 I3 mJy S1.2d ? Integrated 1.2mm flux within 0.25pc diameter
49- 50 I2 Msun Mass ? Mass within 0.25pc diameter
52- 55 F4.1 K Trot ? NH3 rotational temperature
57- 59 F3.1 K e_Trot ? Trot uncertainty
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- HEC High extinction cloud name (GLLL.ll+BB.bb)
14 A1 --- m_HEC [A-D] Subgrouping of cloud based on the
kinematic distance
16- 18 A3 --- mm Millimeter clump number
20- 25 F6.2 km/s Vlsr NH3(1,1) velocity in the local standard of
rest (LSR)
27- 30 F4.2 km/s e_Vlsr Vlsr uncertainty
32- 34 F3.1 K Tmb NH3(1,1) main beam temperature
36- 38 F3.1 K e_Tmb Tmb uncertainty
40- 42 F3.1 km/s dV NH3(1,1) line width
44- 46 F3.1 km/s e_dV dV uncertainty
48- 50 F3.1 --- tau NH3(1,1) main group optical depth
52- 54 F3.1 --- e_tau tau uncertainty
56- 58 F3.1 K Tmb2 ? NH3(2,2) main beam temperature
60- 62 F3.1 K e_Tmb2 ? Tmb2 uncertainty
64- 66 F3.1 km/s dV2 ? NH3(2,2) line width
68- 70 F3.1 km/s e_dV2 ? dv2 uncertainty
72- 74 F3.1 K Tmb3 ? NH3(3,3) main beam temperature
76- 78 F3.1 K e_Tmb3 ? Tmb3 uncertainty
80- 82 F3.1 km/s dV3 ? NH3(3,3) line width
84- 86 F3.1 km/s e_dV3 ? dV3 uncertainty
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- HEC High extinction cloud name (GLLL.ll+BB.bb)
14 A1 --- m_HEC [A-D] Subgrouping of cloud based on the
kinematic distance
16- 18 A3 --- mm Millimeter clump number
20- 22 F3.1 kpc dkin Kinematic distance
24- 26 I3 mag Av Visual extinction based on NH2 from the
1.2mm emission
28- 31 F4.2 pc FWHM Size at FWHM
33- 36 F4.1 10+22cm-2 NH2 Hydrogen column density
38- 40 F3.1 10+5cm-3 nH2 Hydrogen volume density
42- 44 I3 Msun M1.2 Cloud mass derived from the 1.2mm
46- 48 I3 Msun M1.2d Mass within 0.25pc diameter
50- 52 I3 Msun Mvir ? Virial mass
54- 57 F4.1 K Trot ? NH3 rotational temperature
59- 61 F3.1 K e_Trot ? Trot uncertainty
63- 65 F3.1 10+15cm-2 nNH3 ? NH3 column density
67- 69 F3.1 10+15cm-2 e_nNH3 ? NNH3 uncertainty
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Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- FileName Name of the FITS file in subdirectory "ce"
13- 19 F7.3 deg GLON Galactic longitude, image center
21- 25 F5.3 deg GLAT [0] Galactic latitude, image center
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Byte-by-byte Description of file: fig5.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- FileName Name of FITS file (GLLll), in the
"mambo" subdirectory, with 1.2mm map
12- 13 I2 h RAh Right ascension (J2000), image center
15- 16 I2 min RAm Right ascension (J2000), image center
18- 22 F5.2 s RAs Right ascension (J2000), image center
24 A1 --- DE- Declination sign (J2000), image center
25- 26 I2 deg DEd Declination (J2000), image center
28- 29 I2 arcmin DEm Declination (J2000), image center
31- 34 F4.1 arcsec DEs Declination (J2000), image center
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Acknowledgements:
Kazi Rygl, kazi(at)mpifr-bonn.mpg.de
History:
* 01-Aug-2010: Insert into VizieR
* 06-May-2011: Tables 2-5 and 7 added (from electronic version).
(End) Patricia Vannier [CDS] 22-Apr-2010