Issue |
A&A
Volume 422, Number 3, August II 2004
|
|
---|---|---|
Page(s) | 865 - 881 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20040230 | |
Published online | 16 July 2004 |
Molecular gas in the galaxy M 83*
II. Kinematics of the molecular gas
1
Stockholm Observatory, AlbaNova, 10691 Stockholm, Sweden e-mail: andreas@astro.su.se
2
European Southern Observatory, Casilla 19001, Santiago 19, Chile
3
ESA Space Telescpe Division, STScI, 3700 San Martin Drive Baltimore, MD 21218, USA
4
Onsala Space Observatory, 43992 Onsala, Sweden
Received:
9
February
2004
Accepted:
5
April
2004
We present the kinematics of the molecular gas in the barred spiral
galaxy M 83 (NGC 5236). The study is based on 12CO( 1–0 and
2–1) observations with the Swedish-ESO Submillimetre Telescope (SEST).
Iso-velocity maps of the entire optical disk,
10′
10′ or 13
13 kpc, are
produced. They show the pattern of an inclined, rotating disk, but also
the effects of streaming motions along the spiral arms. A dynamical
mass of about 6
10
is estimated by fitting the rotation curve of an exponential disk
model to these data. The
gas constitutes about 13% of the disk mass.
The pattern speed is determined from the residual velocity pattern.
The locations of various resonances are discussed. The molecular gas
velocity dispersion is determined, and a trend of decreasing dispersion
with increasing galactocentric radius is found. A total gas
(H2 +
+ He) mass surface density map is presented, and compared to
the critical density for star formation of an isothermal gaseous disk.
The critical density is exceeded in the spiral arms, but not in the
interarm regions. The locations of Giant Molecular Associations (GMAs) and
regions are consistent with this scenario of dynamically induced star formation.
Key words: galaxies: individual: M 83 (NGC 5236) / galaxies: spiral / galaxies: kinematics and dynamics / galaxies: structure / galaxies: ISM / radio lines: galaxies
© ESO, 2004
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