Issue |
A&A
Volume 478, Number 2, February I 2008
|
|
---|---|---|
Page(s) | 403 - 407 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20078845 | |
Published online | 20 November 2007 |
Discovery of ultra-compact nuclear rings in three spiral galaxies
1
Instituto de Astrofísica de Canarias, 38200 La Laguna, Spain e-mail: sebastien@iac.es
2
Consejo Superior de Investigaciones Científicas, Spain
3
Department of Physics and Astronomy, University of Kentucky, Lexington, USA
Received:
12
October
2007
Accepted:
13
November
2007
Ring-shaped morphologies of nuclear star-forming regions within the
central pc of disk galaxies have been barely resolved so far
in three composite Sy 2 nuclei, the Sy 2 Circinus galaxy and in three
non-AGN galaxies. Such morphologies resemble those of the standard
~1 kpc-size nuclear rings that lie in the inner Lindblad
resonance regions of disk galaxies and, if they have a similar origin,
represent recent radial gas inflows tantalisingly close to the central
supermassive black holes. We aim to identify the population of such
ultra-compact nuclear rings (UCNRs) and study their properties in
relation to those of the host galaxies. From archival Hubble
Space Telescope UV and Hα images and from dust structure maps of
the circumnuclear regions in nearby galaxies, we analyse the morphology
of the star formation and dust, specifically searching for ring
structures on the smallest observable scales. In a sample of 38 galaxies studied, we have detected a total of four new UCNRs,
pc in radius, in three different galaxies. Including our
confirmation of a previous UCNR detection, this yields a UCNR fraction
of roughly 10%, although our sample is neither complete nor
unbiased. For the first time we resolve UCNRs in two LINERs. Overall
the UCNR phenomenon appears widespread and limited neither to late-type
galaxies nor exclusively to AGN hosts.
Key words: galaxies: spiral / galaxies: nuclei / galaxies: starburst
© ESO, 2008
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