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J/A+A/601/A4        IRC+10216 carbon chains mapped with ALMA    (Agundez+, 2017)

Growth of carbon chains in IRC+10216 mapped with ALMA. Agundez M., Cernicharo J., Quintana-Lacaci G., Castro-Carrizo A., Velilla Prieto L., Marcelino N., Guelin M., Joblin C., Martin-Gago J.A., Gottlieb C.A., Patel N.A., McCarthy M.C. <Astron. Astrophys. 601, A4 (2017)> =2017A&A...601A...4A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, carbon ; Radio lines Keywords: astrochemistry - molecular processes - techniques: interferometric - stars: AGB and post-AGB - circumstellar matter - radio lines: stars Abstract: Linear carbon chains are common in various types of astronomical molecular sources. Possible formation mechanisms involve both bottom-up and top-down routes. We have carried out a combined observational and modeling study of the formation of carbon chains in the C-star envelope IRC +10216, where the polymerization of acetylene and hydrogen cyanide induced by ultraviolet photons can drive the formation of linear carbon chains of increasing length. We have used ALMA to map the emission of 3 mm rotational lines of the hydrocarbon radicals C2H, C4H, and C6H, and the CN-containing species CN, C3N, HC3N, and HC5N with an angular resolution of 1". The spatial distribution of all these species is a hollow 5-10" wide spherical shell located at a radius of 10-20" from the star, with no appreciable emission close to the star. Our observations resolve the broad shell of carbon chains into thinner subshells that are 1-2" wide and not fully concentric, indicating that the mass-loss process has been discontinuous and not fully isotropic. The radial distributions of the species mapped reveal subtle differences: while the hydrocarbon radicals have very similar radial distributions, the CN-containing species show more diverse distributions, with HC3N appearing earlier in the expansion and the radical CN extending later than the rest of the species. The observed morphology can be rationalized by a chemical model in which the growth of polyynes is mainly produced by rapid gas-phase chemical reactions of C2H and C4H radicals with unsaturated hydrocarbons, while cyanopolyynes are mainly formed from polyynes in gas-phase reactions with CN and C3N radicals. Description: The FITS files contain the emission maps of carbon chains shown in Figures 1, A1, A2, A3, A4, and A5 of the article. Objects: --------------------------------------------------- RA (2000) DE Designation(s) --------------------------------------------------- 09 47 57.41 +13 16 43.6 IRC+10216 = V* CW Leo --------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 99 26 List of fits images fits/* 0 26 Individual fits images
See also: J/A+A/330/676 : IRC+10216 Silicon and sulfur chemistry (Willacy+ 1998) J/ApJ/688/L83 : Detection of C5N- in IRC +10216 (Cernicharo+, 2008) J/ApJS/177/275 : 1.3 and 2mm survey of IRC+10216 (He+, 2008) J/ApJS/190/348 : 1mm spectral survey of IRC+10216 + VY CMa (Tenenbaum+, 2010) J/ApJS/193/17 : Spectral-line survey of IRC+10216 at 293-355GHz (Patel+, 2011) J/A+A/545/A12 : Chemistry of IRC+10216 inner wind modelled (Cherchneff, 2012) J/ApJ/806/L3 : Disilicon carbide (SiCSi) in CW Leo (Cernicharo+, 2015) J/A+A/574/A56 : IRC +10216 17.8GHz-26.3GHz spectrum (Gong+, 2015) 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- 23 I4 --- Nx Number of pixels along X-axis 25- 28 I4 --- Ny Number of pixels along Y-axis 30- 37 F8.1 m/s RV Radial velocity 39- 43 I5 Kibyte size Size of FITS file 45- 60 A16 --- FileName Name of FITS file, in subdirectory fits 62- 99 A38 --- Title Title of the FITS file
Acknowledgements: Marcelino Agundez, marcelino.agundez(at)icmm.csic.es
(End) Marcelino Agundez [ICMM], Patricia Vannier [CDS] 24-Apr-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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