Query : 2003A&A...397..181M

2003A&A...397..181M - Astronomy and Astrophysics, volume 397, 181-189 (2003/1-1)

Multitransitional observations of the CS core of L673.


Abstract (from CDS):

A multitransitional study with the BIMA interferometric array was carried out toward the starless core found in the L673 region, in order to study the small-size structure of the cores detected with previous single-dish observations, which provides us with a test of the predictions of the chemical model of Taylor et al. (1996A&A...313..269T, 1998A&A...336..309). We detected emission in the CS (J=2->1), N2H+ (J=1->0), and HCO+ (J=1->0) lines. Several clumps of size ≲0.08pc were found for each line distributed all over the region where previous single-dish emission was found (Morata et al., 1997MNRAS.292..120M). Each molecular transition traces differently the clump distribution, although in some cases the detected clumps are coincident. The distribution of the N2H+ emission and the single-dish NH3 emission are coincident and compatible with an origin in the same gas. The large fraction of missing flux measured for the CS (2->1) transition can be explained if the cloud is formed by a clumpy and heterogeneous medium. Four positions were selected to derive the abundance ratios [N2H+/CS] and [HCO+/CS] from the molecular column density determinations, and to compare them with the values predicted by the chemical model. The model was able to explain the interferometric observations, and, in particular, the chemical differentiation of the detected clumps and the coincidence of the NH3 and N2H+ emissions. The lack of HCO+ towards the two selected positions that trace the more evolved clumps cannot be accounted for by the model, but it is possibly due to strong self-absorption. We propose a classification of the studied clumps according to the stage of chemical evolution indicated by the molecular abundances.

Abstract Copyright:

Journal keyword(s): molecular processes - ISM: abundances - ISM: clouds - ISM: molecules - ISM: individual objects: L673

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Mon OB1 G PoC 06 41 12 +09 55.6           ~ 107 0
2 4C 09.57 BLL 17 51 32.81857326 +09 39 00.7284066   17.46 16.78 15.57   ~ 916 1
3 ICRF J190255.9+315941 Sy1 19 02 55.93889653 +31 59 41.7016439     17.5     ~ 269 2
4 IRAS 19180+1116 IR 19 20 22.5 +11 22 07           ~ 17 0
5 LDN 673 DNe 19 20 54.4 +11 13 12           ~ 73 0
6 IC 5146 OpC 21 53 29.3 +47 14 46           ~ 455 2

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