Issue |
A&A
Volume 392, Number 2, September III 2002
|
|
---|---|---|
Page(s) | 473 - 487 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20020953 | |
Published online | 30 August 2002 |
HI distribution and kinematics of NGC 1569
1
Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
2
Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, Canada
Corresponding author: J. M. Stil, stil@ras.ucalgary.ca
Received:
26
March
2002
Accepted:
20
June
2002
We present WSRT observations of high sensitivity and
resolution of the neutral hydrogen in the starburst dwarf galaxy
NGC 1569. Assuming a distance of 2.2 Mpc, we find a total HI mass of
to be distributed in the form of a
dense, clumpy ridge surrounded by more extended diffuse HI containing
a few additional discrete features, such as a Western HI Arm and an HI
bridge reaching out to a small counterrotating companion cloud. About
10% by mass of all HI in NGC 1569 is at unusually high
velocities. Some of this HI may be associated with the mass outflow
evident from Hα measurements, but some may also be associated
with NGC 1569's HI companion and intervening HI bridge, in which case,
infall rather than outflow might be the cause of the discrepant
velocities. No indication of a large bubble structure was found
in position-velocity maps of the high-velocity HI. The galaxy as a
whole is in modest overall rotation, but the HI gas lacks any sign of
rotation within
(0.6 kpc) from the center, i.e. over most of
the optical galaxy. Here, turbulent motions resulting from the starburst
appear to dominate over rotation. In the outer disk, the
rotational velocities reach a maximum of
,
but turbulent motion remains significant. Thus, starburst effects are
still noticeable in the outer HI disk, although they are no longer
dominant beyond 0.6 kpc. Even excluding the most extreme high-velocity
HI clouds, NGC 1569 still has an unusually high mean HI velocity
dispersion of
, more than double that of
other dwarf galaxies.
Key words: ISM: atoms / galaxies: individual: NGC 1569 / irregular / kinematics and dynamics / starburst
© ESO, 2002
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