Issue |
A&A
Volume 409, Number 3, October III 2003
|
|
---|---|---|
Page(s) | 879 - 886 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20031163 | |
Published online | 17 November 2003 |
Kinematics of the dwarf irregular galaxy GR8
National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune 411 007, India
Corresponding authors: A. Begum, ayesha@ncra.tifr.res.in chengalur@ncra.tifr.res.in
Received:
15
May
2003
Accepted:
22
July
2003
We present deep, high velocity resolution (~1.6 km s-1)
Giant Meterwave Radio Telescope HI 21 cm synthesis images for the faint
() dwarf irregular galaxy GR8. We find that the velocity
field of the galaxy shows a clear systematic large scale pattern, with
a maximum amplitude ~10 km s-1. Neither pure rotation, nor pure
radial motion alone can fit the observed velocity field; however a
combination of radial and circular motions can provide a reasonable
fit. The most natural interpretation is that the neutral ISM, in addition
to rotating about the center, is also expanding outwards, as a result of
energy input from the ongoing star formation in the galaxy. Support
for this interpretation comes from the fact that the pressure in the
HII regions in the galaxy is known to be substantially
(~55 times)
higher than the average pressure in the gas disk. It is, however, also
possible that the velocity field is the result of the gas swirling
inwards, in which case GR8 could be in the process of formation via
the merger of subgalactic clumps.
Key words: galaxies: evolution / galaxies: dwarf / galaxies: kinematics and dynamics / galaxies: individual: GR8 radio lines: galaxies
© ESO, 2003
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