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Astron. Astrophys. 358, 144-153 (2000)


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Studies of binary star cluster candidates in the bar of the LMC

I. SL 353 and SL 349 *

A. Dieball 1, E.K. Grebel **  2 and C. Theis 3

1 Sternwarte der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
2 University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195-1580, USA
3 Institut für Theoretische Physik und Astrophysik der Universität Kiel, 24098 Kiel, Germany

Received 22 December 1999 / Accepted 27 March 2000

Abstract

We present a detailed study of the cluster pair SL 353 & SL 349. This candidate binary cluster is located at the northwestern rim of the LMC bar. Based on photometric data we find that both clusters are coeval with an age of 550[FORMULA]100 Myr. We use the Ca II triplet in the spectra of individual red giants to derive radial velocities. Both components of the binary cluster candidate show very similar mean velocities ([FORMULA] km [FORMULA] for SL 349 and [FORMULA] km [FORMULA] for SL 353) while the field stars show lower velocities ([FORMULA] km [FORMULA]). These findings suggest a common origin of the two clusters from the same GMC. In this sense the cluster pair may constitute a true binary cluster. We furthermore investigate the stellar densities in and around the star clusters and compare them with isopleths created from artificial, interacting as well as non-interacting star clusters. Gravitational interaction leads to a distortion which can also be found in the observed pair.

Key words: stars: Hertzsprung – Russel (HR) and C-M diagrams – stars: kinematics – galaxies: clusters: individual: SL 353, individual: SL 349 – galaxies: Magellanic Clouds

* Based on observations taken at the European Southern Observatory, La Silla, Chile.
** Hubble fellow

Send offprint requests to: A. Dieball (adieball@astro.uni-bonn.de)

© European Southern Observatory (ESO) 2000

Online publication: June 26, 2000

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