2007A&A...471..561N


C.D.S. - SIMBAD4 rel 1.7 - 2020.04.05CEST21:57:27

2007A&A...471..561N - Astronomy and Astrophysics, volume 471, 561-571 (2007/8-4)

CO and CS in the Magellanic Clouds: a χ2-analysis of multitransitional data based on the MEP radiative transfer model.

NIKOLIC S., GARAY G., RUBIO M. and JOHANSSON L.E.B.

Abstract (from CDS):

Our goal is to determine the physical properties of molecular gas located in different environments of the SMC - from near the vicinity of hot HII regions to cold, quiescent clouds - via modelling and simulations, and compare with the properties of molecular gas found in similar environments in the LMC. We present observations of the 12CO(1-0), (2-1), (3-2), 13CO(1-0), (2-1), and CS(2-1), (3-2) line emission toward six molecular clouds in the SMC: N66, N88, Lirs36, Lirs49, Hodge15, and SMC-B1#1. These data, as well as published data on three clouds of the LMC: 30Dor-10, N159-W, and N159-S, are analysed to estimate gas kinetic temperatures, column densities, and surface filling factors using a Mean Escape Probability approximation of the radiative transfer equations. The solutions are restricted using the χ2 approach. Assuming that the [12CO/13CO] abundance ratio is similar in both galaxies, we find that the CO and CS column densities of SMC clouds are a magnitude smaller than those of LMC clouds, mirroring the metallicity differences. Our analysis suggests the existence of a lower limit for the 12CO/13CO isotope ratio of 50 in both galaxies. The surface filling factors of the CO emission in the SMC clouds are a factor of a few smaller than in the LMC and seem to decrease with increasing UV radiation fields, i.e., more vigorous star formation activity. A simple model, which assumes a spherical cloud with uniform physical parameters immersed in the CMB radiation field, provides a reasonably good fit to the observed properties of the (supposedly) quiescent clouds SMC-B1#1 and N159-S. For all other clouds considered, this model gives large values of χ2, strongly indicating the need for a more complex model. We present some results from 2-component modelling, e.g., for Lirs 36 a mixture of 20K gas with high optical depth and a less dense gas with temperatures of 100K reproduces well the main features of the CO data.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: molecules - galaxies: ISM - galaxies: Magellanic Clouds

Status at CDS:  

Simbad objects: 18

goto Full paper

goto View the reference in ADS

Number of rows : 18

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 [RLB93] SMC-B1 1 MoC 00 45 32.7 -73 18 46           ~ 33 0
2 NGC 261 HII 00 46 31.5 -73 06 16           ~ 61 1
3 [H74] 15 DNe 00 48 10.9 -73 13 49           ~ 7 0
4 LHA 115-N 12 HII 00 48 12 -73 16.2           ~ 31 0
5 LHA 115-N 27 Em* 00 48 24.0 -73 05 50           ~ 58 0
6 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9293 1
7 SNR B0057-72.2 SNR 00 59 27.40 -72 10 10.7   12.37 12.57     ~ 216 0
8 LHA 115-N 88A HII 01 24 07.823 -73 09 03.77   13.25 12.18     ~ 68 1
9 LHA 115-N 88 HII 01 24 08.1 -73 09 04           ~ 68 1
10 DEM S 161 HII 01 24 45.4 -73 09 34           ~ 16 0
11 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5546 1
12 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14625 1
13 NAME 30 Dor Nebula SFR 05 38 36.0 -69 05 11           ~ 1032 2
14 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1708 1
15 [MMM2008] 30 Dor 1 MoC 05 38 50.8 -69 04 15           ~ 22 0
16 [MMM2008] N159 1 MoC 05 39 35.1 -69 45 25           ~ 7 0
17 [MMM2008] N159 4 MoC 05 39 58.7 -69 50 29           ~ 6 0
18 NAME Local Group GrG ~ ~           ~ 6851 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2007A&A...471..561N and select 'bookmark this link' or equivalent in the popup menu


2020.04.05-21:57:27

© Université de Strasbourg/CNRS

    • Contact