SIMBAD references

2007ApJ...671.1579M - Astrophys. J., 671, 1579-1590 (2007/December-3)

Formaldehyde as a tracer of extragalactic molecular gas. I. Para-H2 CO emission from M 82.


Abstract (from CDS):

Using the IRAM 30 m telescope and the 15 m JCMT, we explore the value of paraformaldehyde (p-H2CO) as a tracer of density and temperature of the molecular gas in external galaxies. The target of our observations are the lobes of the molecular ring around the center of the nearby prototypical starburst galaxy M82. It is shown that p-H2 CO provides one of the rare direct molecular thermometers. Reproducing the measured line intensities with a large velocity gradient (LVG) model, we find densities of nH2∼7x103/cm3 and kinetic temperatures of Tkin∼200 K. The derived kinetic temperature is significantly higher than the dust temperature or the temperature deduced from ammonia (NH3) lines, but our results agree well with the properties of the high-excitation component seen in CO. We also present the serendipitous discovery of the 42⟶31 line of methanol (CH3OH) in the northeastern lobe, which shows–unlike CO and H2CO–significantly different line intensities in the two lobes.

Abstract Copyright:

Journal keyword(s): Galaxies: Individual: Messier Number: M82 - Galaxies: ISM - Galaxies: Starburst - ISM: Molecules - Radio Lines: ISM - Submillimeter

CDS comments: Fig.2 : SNR 41.95+57.5 in M82 is [MPW94] 41.95+57.5

Simbad objects: 11

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