| Issue |
A&A
Volume 543, July 2012
|
|
|---|---|---|
| Article Number | L7 | |
| Number of page(s) | 4 | |
| Section | Letters | |
| DOI | https://doi.org/10.1051/0004-6361/201219075 | |
| Published online | 11 July 2012 | |
The globular cluster system of NGC 1316
II. The extraordinary object SH2⋆
1 Departamento de Astronomía, Casilla 160-CUniversidad de Concepción, Concepción, Chile
e-mail: tom@astro-udec.cl
2 Aryabhatta Research Institute of Observational Sciences, Manora Peak, 263129 Nainital, India
3 Facultad de Ciencias Astronómicas y Geofísicas de la Universidad Nacional de La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, and Instituto de Astrofísica de La Plata (CCT La Plata-CONICET-UNLP), Buenos Aires, Argentina
4 Friedrich-Ebert-Gymnasium, 53113 Bonn, Germany
5 UCO/Lick Observatory, University of California, Santa Cruz, CA 95064, USA
Received: 20 February 2012
Accepted: 28 February 2012
Context. SH2 has been described as an isolated HII-region, located about 6.5′ south of the nucleus of NGC 1316 (Fornax A), a merger remnant in the the outskirts of the Fornax cluster of galaxies.
Aims. We give a first, preliminary description of the stellar content and environment of this remarkable object.
Methods. We used photometric data in the Washington system and HST photometry from the Hubble Legacy Archive for a morphological description and preliminary aperture photometry. Low-resolution spectroscopy provides radial velocities of the brightest star cluster in SH2 and a nearby intermediate-age cluster.
Results. SH2 is not a normal HII-region, ionized by very young stars. It contains a multitude of star clusters with ages of approximately 108 yr. A ring-like morphology is striking. SH2 seems to be connected to an intermediate-age massive globular cluster with a similar radial velocity, which itself is the main object of a group of fainter clusters. Metallicity estimates from emission lines remain ambiguous.
Conclusions. The present data do not yet allow firm conclusions about the nature or origin of SH2. It might be a dwarf galaxy that has experienced a burst of extremely clustered star formation. We may witness how globular clusters are donated to a parent galaxy.
Key words: galaxies: star clusters: general / galaxies: clusters: individual: NGC 1316 / galaxies: peculiar / galaxies: ISM
Based on observations taken at the European Southern Observatory, Cerro Paranal, Chile, under the programmes 082.B-0680, on observations taken at the Interamerican Observatory, Cerro Tololo, Chile. Furthermore based on observations made with the NASA/ESA Hubble Space Telescope (HST, PI: A. Sandage, Prop.ID: 7504), and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA).
© ESO, 2012
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