Journal Article

Trumpler 20 – an old and rich open cluster*†‡

I. Platais, C. Melo, J. P. Fulbright, V. Kozhurina-Platais, P. Figueira, S. A. Barnes and R. A. Méndez

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 391, issue 3, pages 1482-1488
Published in print December 2008 | ISSN: 0035-8711
Published online November 2008 | e-ISSN: 1365-2966 | DOI:
Trumpler 20 – an old and rich open cluster*†‡

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We show that the open cluster Trumpler 20, contrary to the earlier findings, is actually an old Galactic open cluster. New CCD photometry and high-resolution spectroscopy are used to derive the main parameters of this cluster. At [Fe/H]=−0.11 for a single red giant star, the metallicity is slightly subsolar. The best fit to the colour–magnitude diagrams is achieved using a 1.3-Gyr isochrone with convective overshoot. The cluster appears to have a significant reddening at E(BV) = 0.46 (for B0 spectral type), although for red giants this high reddening yields the colour temperature exceeding the spectroscopic Teff by about 200 K. Trumpler 20 is a very rich open cluster, containing at least 700 members brighter than MV=+4. It may extend over the field of view available in our study at 20 × 20 arcmin2.

Keywords: stars: abundances; open clusters and associations: individual: Trumpler 20

Journal Article.  4581 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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