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J/A+A/597/A45       W51 line of sight deuterium fractionation    (Vastel+, 2017)

Deuterium fractionation of a distant cold dark cloud along the line of sight of W51. Vastel C., Mookerjea B., Pety J., Gerin M. <Astron. Astrophys. 597, A45 (2017)> =2017A&A...597A..45V (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Spectroscopy Keywords: astrochemistry - line: identification - molecular data - radiative transfer Abstract: Herschel/HIFI observations toward the compact HII region W51 has revealed the presence of a cold dense core along its line of sight in a high-velocity stream located just in front of W51. This detection has been made possible through absorption measurements of low-energy transitions of HDO, NH3, and C3 against the bright background emitted by the star-forming region. We present a follow-up study of this core using the high sensitivity and high spectral resolution provided by the IRAM 30m telescope. We report new detections of this core in absorption for DCO+ (2-1, 3-2), H13CO+ (1-0), DNC (3-2), HN13C (1-0), p-H2CO (20,2-10,1, 30,3-20,2), and in emission for o-NH2D. We also report interferometric observation of this last species using the IRAM/NOEMA telescope, revealing the fragmented nature of the source through the detection of two cores, separated by 0.19-0.24pc, with average sizes of less than 0.16-0.19pc. From a non-LTE analysis, we are able to estimate the density (∼2.5x104cm-3) and temperature (∼10K) of this component, typical of what is found in dark clouds. This component (called W51-core) has the same DCO+/HCO+ ratio (0.02) as TMC-1 and a high DNC/HNC ratio (0.14). Detection of these deuterated species indicates that W51-core is similar to an early-phase low-mass star-forming region, formed from the interaction between the W51 giant molecular cloud and the high-velocity stream in front of it. The W51 complex being at about 5kpc, these findings lead to what is the first detection of the earliest phase of low-mass star-forming region at such a large distance. Description: The fits file have been generated under the GILDAS CLASS command, between 40 and 90km/s. Objects: ---------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------- 19 23 50 +14 06.0 W51 = SNR G049.2-00.5 ---------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 118 9 List of fits spectra fits/* 0 9 Individual fits spectra
See also: J/ApJS/191/232 : CO survey of W51 molecular cloud (Bieging+, 2010) J/MNRAS/424/1658 : Molecular clumps in W51 giant mol. cloud (Parsons+, 2012) J/A+A/582/A64 : W51/e2 and G34.3+0.2 IRAM spectra (Lykke+, 2015) J/A+A/589/A44 : W51 Main NH3 and CH3OH data cubes (Goddi+, 2016) J/A+A/595/A27 : JVLA images of W51A (Ginsburg+, 2016) Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000) 10- 18 F9.5 deg DEdeg Declination of center (J2000) 20- 22 I3 --- Nx Number of pixels along X-axis 24- 46 A23 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.sss) 48- 55 F8.4 GHz bFreq Lower value of frequency interval 57- 63 F7.4 GHz BFreq Upper value of frequency interval 65- 71 F7.1 Hz dFreq Frequency resolution 73- 74 I2 Kibyte size Size of FITS file 76- 88 A13 --- FileName Name of FITS file, in subdirectory fits 90-118 A29 --- Title Title of the FITS file
Acknowledgements: Charlotte Vastel, cvastel(at)
(End) Patricia Vannier [CDS] 15-Nov-2016
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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