2000ApJ...542..870D -
Astrophys. J., 542, 870-889 (2000/October-3)
A study of the physics and chemistry of L134N.
DICKENS J.E., IRVINE W.M., SNELL R.L., BERGIN E.A., SCHLOERB F.P., PRATAP P. and MIRALLES M.P.
Abstract (from CDS):
We have carried out a comprehensive and self-consistent study of the physical and chemical state of the core of the dark cloud L134N (L183), whose molecular abundances provide a standard against which chemical models may be compared. We used observations of the NH3(1, 1) and (2, 2) rotation-inversion transitions to estimate the kinetic temperature, which was found to be consistent with 10 K and not varying with position. Densities were determined from multitransition statistical equilibrium calculations for HC3N, N2H+, and CS. The average density toward all lines of sight was 2x104 cm–3. As found by previous studies, the emission from various molecular species peaks in different positions: SO and SO2 peak west of the central position, which is the location of the strongest emission from (e.g.) N2H+ and CH3OH, with a second peak occurring for NH3 and HC3N to the north of the center. The most striking abundance variations occur in a north-south cut through the core center for HC3N, C2H, CS, SO, and SO2. A north to south decrease in the abundance of HC3N and CS and a dramatic change in the CS/SO ratio, which has been shown to be a sensitive tracer of chemical evolutionary state, suggests that the north is at a younger evolutionary state than the south. Despite the ``youth'' of the N position, the CS/SO ratio suggests that it is still as ``old'' as or older than the most evolved region in TMC-1 (the northwest end of the ridge).
Abstract Copyright:
∼
Journal keyword(s):
ISM: Abundances - ISM: Individual: Alphanumeric: L134N - ISM: Molecules
Simbad objects:
6
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2000ApJ...542..870D and select 'bookmark this link' or equivalent in the popup menu