Trumpler 20 - an old and rich open cluster

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

Source: Monthly Notices of the Royal Astronomical Society, Volume 391, Number 3, December 2008 , pp. 1482-1488(7)

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Abstract:

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(B−V) = 0.46 (for B0 spectral type), although for red giants this high reddening yields the colour temperature exceeding the spectroscopic T_eff by about 200 K. Trumpler 20 is a very rich open cluster, containing at least 700 members brighter than M_V=+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: Trumpl

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.14011.x

Publication date: 2008-12-01