2002A&A...391..275H


C.D.S. - SIMBAD4 rel 1.7 - 2020.04.02CEST12:41:22

2002A&A...391..275H - Astronomy and Astrophysics, volume 391, 275-285 (2002/8-3)

C18O abundance in the nearby globule Barnard 68.

HOTZEL S., HARJU J., JUVELA M., MATTILA K. and HAIKALA L.K.

Abstract (from CDS):

We have studied the radial variation of the CO abundance in the nearby isolated globule Barnard 68 (B68). For this purpose, B68 was mapped in the three rotational lines 13CO(J=1-0), C18O(J=1-0) and C18O(J=2-1). Using the recent discovery of Alves et al. (2001Natur.409..159A) that the density structure of B68 agrees with the prediction for a pressure bound distribution of isothermal gas in hydrostatic equilibrium (Bonnor-Ebert sphere), we show that the flat CO column density distribution can be explained by molecular depletion. By combining the physical model with the observed CO column density profile, it was found that the density dependence of the CO depletion factor fd can be well fitted with the law fd=1+const.n(H2), which is consistent with an equilibrium between the accretion and the desorption processes. In the cloud centre, between 0.5% and 5% of all CO molecules are in the gas phase. Our observations suggest a kinetic temperature of ≃8K. In combination with the assumption that B68 is a Bonnor-Ebert sphere, this leads to a distance of 80pc. The cloud mass consistent with these values is 0.7M, considerably less than previously estimated. We find in B68 no clear deviance of the near-infrared reddening efficiency of dust grains per unit H2 column density with respect to values derived in diffuse clouds.

Abstract Copyright:

Journal keyword(s): ISM: individual objects: Barnard 68 - ISM: abundances - ISM: molecules - ISM: dust, extinction

Status at CDS:  

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 [BCB89] IRS 2 * 05 41 45.81 -01 54 29.8           B 91 0
2 HD 73882 EB* 08 39 09.53412 -40 25 09.2608 7.07 7.59 7.19 6.67 6.30 O8.5IV 217 2
3 HD 110432 Be* 12 42 50.2655719413 -63 03 31.048323668 4.79 5.58 5.31     B0.5IVpe 266 0
4 * rho Oph A * 16 25 35.142 -23 26 49.90 4.3 5.22 5.05     B2/3V 382 0
5 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 2980 0
6 LDN 57 DNe 17 22 38.2 -23 49 34           ~ 278 1
7 NAME CrA Dark Cloud MoC 19 01 51 -36 58.9           ~ 389 0

    Equat.    Gal    SGal    Ecl

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2020.04.02-12:41:22

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