Query : 2001A&A...365..571W

2001A&A...365..571W - Astronomy and Astrophysics, volume 365, 571-587 (2001/1-3)

The effect of violent star formation on the state of the molecular gas in M82.


Abstract (from CDS):

We present the results of a high angular resolution, multi-transition analysis of the molecular gas in M 82. The analysis is based on the two lowest transitions of 12CO and the ground transition of the rare isotopes 13CO and C18O measured with the PdBI, the BIMA array and the IRAM 30 m telescope. In order to address the question of how the intrinsic molecular cloud properties are influenced by massive star formation we have carried out radiative transfer calculations based on the observed CO line ratios. The calculations suggest that the kinetic temperature of the molecular gas is high in regions with strong star formation and drops towards the outer molecular lobes with less ongoing star formation. The location of the highest kinetic temperature is coincident with that of the mid infrared (MIR) peaks which trace emission from hot dust. The hot gas is associated with low H2 densities while the cold gas in the outer molecular lobes has high H2 densities. We find that CO intensities do not trace H2 column densities well. Most of the molecular gas is distributed in a double-lobed distribution which surrounds the starburst. A detailed analysis of the conversion factor from CO intensity to H2 column density shows that XCO depends on the excitation conditions. We find XCO∼Tkin–1n(H2)1/2, as expected for virialized clouds.

Abstract Copyright:

Journal keyword(s): ISM: evolution - ISM: molecules - ISM: structure - galaxies: individual: M 82 - galaxies: ISM - galaxies: starburst

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 NGC 253 SyG 00 47 33.134 -25 17 19.68   8.03   6.94 8.1 ~ 3344 2
2 CXOM82 J095550.9+694044 HXB 09 55 50.690 +69 40 43.76           ~ 96 0
3 M 82 AGN 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5869 6
4 3C 273 BLL 12 29 06.6998257176 +02 03 08.597629980   13.05 14.830 14.11   ~ 5811 1
5 EM* MWC 349 ** 20 32 45.499080 +40 39 36.74124   15.88 13.15 12.13   Bep 802 0

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