Volume 409, Number 3, October III 2003
|Page(s)||879 - 886|
|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
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
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.