Journal Article

The old metal-poor open cluster ESO 92-SC05: accreted from a dwarf galaxy?

S. Ortolani, E. Bica and B. Barbuy

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 388, issue 2, pages 723-728
Published in print August 2008 | ISSN: 0035-8711
Published online July 2008 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.13427.x
The old metal-poor open cluster ESO 92-SC05: accreted from a dwarf galaxy?

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The study of old open clusters outside the solar circle can bring constraints on formation scenarios of the outer disc. In particular, accretion of dwarf galaxies has been proposed as a likely mechanism in the area. We use BVI photometry for determining fundamental parameters of the faint open cluster ESO 92-SC05. Colour–magnitude diagrams are compared with Padova isochrones, in order to derive age, reddening and distance. We derive a reddening E(BV) = 0.17, and an old age of ∼6.0 Gyr. It is one of the rare open clusters known to be older than 5 Gyr. A metallicity of Z∼ 0.004 or [M/H]∼−0.7 is found. The rather low metallicity suggests that this cluster might be the result of an accretion episode of a dwarf galaxy.

Keywords: Hertzsprung-Russell (HR) diagram; open clusters and associations: individual: ESO 92-SC05

Journal Article.  2732 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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