Issue |
A&A
Volume 375, Number 3, September 2001
|
|
---|---|---|
Page(s) | 797 - 804 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20010860 | |
Published online | 15 September 2001 |
Molecular gas and dust in NGC 4550
A galaxy with two counterrotating stellar disks
1
Onsala Space Observatory, 43992 Onsala, Sweden
2
Max-Planck-Institute für Radioastronomie, Auf dem Hügel 59, 53121 Bonn, Germany
Corresponding author: T. Wiklind, tommy@oso.chalmers.se
Received:
10
April
2001
Accepted:
12
June
2001
We report the detection of
of molecular
gas in the central region of the S0/E7 galaxy NGC 4550, inferred
from observations of CO(1-0) emission. Dust is detected in HST WFPC2
images and found to be asymmetrically distributed around the nucleus,
only extending to a galactocentric distance of 7'' (600 pc). The
shape of the CO emission profile is consistent with a molecular gas
distribution following the dust. The distribution of the dust and
gas in the center could be the result of an
instability, which
is the fastest growing unstable mode in counterrotating stellar disks.
On a global scale the molecular gas in NGC 4550 is stable against
gravitational collapse but nevertheless star formation appears to be
ongoing with normal star formation efficiency and gas consumption
time scales. The stellar velocity dispersion in NGC 4550 resembles
that of elliptical galaxies. It is therefore likely that a hot
X-ray emitting plasma limits the lifetime of the molecular gas,
that must arise from a recent (≪1 Gyr) accretion event.
Key words: ISM: dust, extinction / ISM: molecules / galaxies: elliptical and lenticular, cD / galaxies: individual: NGC 4550 / galaxies: structure
© ESO, 2001
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