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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
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). These can be converted to infrared extinction maps using the interstellar extinction law of Indebetouw et al. (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:
FileName Lrecl Records Explanations
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/* 0 120 FITS files containing the 3.6-4.5um color excess maps mambo/* 0 25 FITS files containing the 1.2mm dust continuum maps
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
Bytes Format Units Label Explanations
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
Byte-by-byte Description of file: table2.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 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.
Byte-by-byte Description of file: table3.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- 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)
Byte-by-byte Description of file: table4.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- 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
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
Byte-by-byte Description of file: table7.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- 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
Byte-by-byte Description of file: fig1.dat
Bytes Format Units Label Explanations
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
Byte-by-byte Description of file: fig5.dat
Bytes Format Units Label Explanations
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
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
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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