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J/ApJ/790/84       Ammonia in high-mass star formation regions       (Lu+, 2014)

Very Large Array observations of ammonia in high-mass star formation regions. Lu X., Zhang Q., Liu H.B., Wang J., Gu Q. <Astrophys. J., 790, 84 (2014)> =2014ApJ...790...84L (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interstellar medium ; YSOs Keywords: ISM: molecules - stars: formation Abstract: We report systematic mapping observations of the NH3(1, 1) and (2, 2) inversion lines toward 62 high-mass star-forming regions using the Very Large Array (VLA) in its D and DnC array configurations. The VLA images cover a spatial dynamic range from 40'' to 3'', allowing us to trace gas kinematics from ∼1 pc scales to ≲ 0.1 pc scales. Based on the NH3 morphology and the infrared nebulosity on 1 pc scales, we categorize three subclasses in the sample: filaments, hot cores, and NH3-dispersed sources. The ubiquitous gas filaments found on 1 pc scales have a typical width of ∼0.1 pc and often contain regularly spaced fragments along the major axis. The spacing of the fragments and the column densities is consistent with the turbulent supported fragmentation of cylinders. Several sources show multiple filaments that converge toward a center where the velocity field in the filaments is consistent with gas flows. We derive rotational temperature maps for the entire sample. For the three hot core sources, we find a projected radial temperature distribution that is best fit by power-law indices from -0.18 to -0.35. We identify 174 velocity-coherent ∼0.1 pc scale dense cores from the entire sample. The mean physical properties for these cores are 1.1 km/s in intrinsic linewidth, 18 K in NH3 rotational temperature, 2.3x1015/cm2 in NH3gas column density, and 67 Min molecular mass. The dense cores identified from the filamentary sources are closer to being virialized. Dense cores in the other two categories of sources appear to be dynamically unstable. Description: We observed 54 high-mass star-forming regions during 2004 June (project code: AC0733), using the NRAO5 VLA in D/DnC array configurations, which constitute a good sample of high-mass protostars given the large luminosity and association with molecular outflows and dense NH3 gas (Molinari et al. 1996, J/A+A/308/573; Sridharan et al. 2002ApJ...566..931S; Beuther et al. 2002A&A...390..289B; Wu et al. 2006A&A...450..607W). The uv distances of the observations range from 2 kλ to ≥ 81 kλ, which yield ≲ 3 arcsec angular resolution and ∼40 arcsec maximal detectable angular scales. The correlator setup provided two independently tunable spectral windows with a 48.8 kHz spectral channel spacing and a 3.125 MHz bandwidth, corresponding to 0.618 km/s channel width and 39 km/s velocity coverage for the NH3 (1, 1) transition. These two spectra windows simultaneously covered the main and two inner satellite transitions of the NH3 (1, 1) line, as well as the main and one inner satellite transitions of the NH3 (2, 2) line. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 58 7 Summary of the VLA Observations table2.dat 94 62 Observational Properties of the Sources table6.dat 83 324 Dense core properties
See also: J/A+A/308/573 : Ammonia on YSOs IRAS sources (Molinari+ 1996) J/A+AS/124/385 : Dense molecular cores. V. (Zinchenko+ 1997) J/ApJS/125/161 : A database of dense cores mapped in ammonia (Jijina+, 1999) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1 I1 --- Index [1/6] Project index 3- 8 A6 --- Project Project name 10- 23 A14 "date" Date Project date 25- 27 A3 --- Config [C,D,DnC ] VLA array configuration 29- 33 A5 --- Dist The uv-distance interval of the observation (in klambda units) 35- 36 I2 --- Num [1/42] Number of samples 38- 54 A17 --- PhaseC Phase calibrator(s) used 56- 58 F3.1 mJy/beam rms rms level (per channel)
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Source Source name 17 I1 --- Index [1/6] Project index defined in table 1 19- 20 I2 h RAh Hour of Right Ascension (J2000) (1) 22- 23 I2 min RAm Minute of Right Ascension (J2000) (1) 25- 29 F5.2 s RAs Second of Right Ascension (J2000) (1) 31 A1 --- DE- Sign of the Declination (J2000) (1) 32- 33 I2 deg DEd Degree of Declination (J2000) (1) 35- 36 I2 arcmin DEm Arcminute of Declination (J2000) (1) 38- 42 F5.2 arcsec DEs Arcsecond of Declination (J2000) (1) 44- 50 F7.3 deg GLON Galactic longitude (1) 52- 57 F6.3 deg GLAT Galactic latitude (1) 58- 69 A12 --- NH3 NH3 line(s) detection 71- 75 F5.1 km/s VLSR ? Local Standard of Rest velocity 77- 80 F4.1 kpc Dist ? Distance 82- 85 A4 --- n_Dist Note on Dist (2) 87- 91 E5.2 Lsun LIR ? IRAS point source luminosity 93- 94 I2 --- Ncore [0/15]? Number of core for this source in table6
Note (1): Coordinates are phase centers of the VLA observations. Note (2): Note as follows: 1 = Sridharan et al. (2002ApJ...566..931S); 2 = Niinuma et al. (2011PASJ...63....9N); 3 = At the tangential point or in the second or third quadrant of the Milky Way; 4 = Wilking et al. (1989ApJ...345..257W); 5 = Fish et al. (2003ApJ...587..701F); 6 = Sato et al. (2010PASJ...62..287S); 7 = IRDC candidates; 8 = Anderson & Bania (2009, J/ApJ/690/706); 9 = Fazal et al. (2008ApJ...688L..41F); 10 = Kurayama et al. (2011PASJ...63..513K); 11 = The far distance is applied because the derived near distance is too small (≤1 kpc).
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 19 A19 --- ID Core identifier 21- 22 I2 h RAh Hour of Right Ascension (J2000) 24- 25 I2 min RAm Minute of Right Ascension (J2000) 27- 31 F5.2 s RAs Second of Right Ascension (J2000) 33 A1 --- DE- Sign of the Declination (J2000) 34- 35 I2 deg DEd Degree of Declination (J2000) 37- 38 I2 arcmin DEm Arcminute of Declination (J2000) 40- 44 F5.2 arcsec DEs Arcsecond of Declination (J2000) 46- 49 F4.2 pc R Intrinsic core radius 51- 54 F4.2 km/s DelV Intrinsic line width 56- 59 F4.1 K TR ? Rotational temperature 61- 66 E6.1 cm-2 NNH3 NH3 column density 68- 73 F6.2 Msun Mcore Core mass 75- 79 F5.1 --- Ratio ? Ratio of virial to core masses 81- 83 A3 --- Multi [yes ] Multi-Velocity flag
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 21-Mar-2017
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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