EDP Sciences
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Volume 412, Number 3, December IV 2003
Page(s) 721 - 725
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20031065

A&A 412, 721-725 (2003)
DOI: 10.1051/0004-6361:20031065

CCD photometric search for peculiar stars in open clusters

V. NGC 2099, NGC 3114, NGC 6204, NGC 6705 and NGC 6756
E. Paunzen1, 2, O. I. Pintado3 and H. M. Maitzen1

1  Institut für Astronomie der Universität Wien, Türkenschanzstr. 17, 1180 Wien, Austria
2  Zentraler Informatikdienst der Universität Wien, Universitätsstr. 7, 1010 Wien, Austria
3  Departamento de Física, Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Argentina - Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina

(Received 7 February 2003 / Accepted 16 June 2003 )

We have investigated 1008 objects in the area of five intermediate age open clusters (NGC 2099, NGC 3114, NGC 6204, NGC 6705 and NGC 6756) via the narrow band $\Delta a$-system. The detection limit for photometric peculiarity is very low (always less than 0.009 mag) due to the high number of individual frames used (193 in total). We have detected six peculiar objects in NGC 6705 and NGC 6756 from which one in the latter is almost certainly an unreddened late type foreground star. The remaining five stars are probably cluster members and bona fide chemically peculiar objects (two are $\lambda$ Bootis type candidates). Furthermore, we have investigated NGC 3114, a cluster for which already photoelectric $\Delta a$-measurements exist. A comparison of the CCD and photoelectric values shows very good agreement. Again, the high capability of our CCD  $\Delta a$-photometric system to sort out true peculiar objects together with additional measurements from broad or intermediate band photometry is demonstrated.

Key words: stars: chemically peculiar -- stars: early-type -- techniques: photometric -- open clusters and associations: general

Offprint request: E. Paunzen, Ernst.Paunzen@univie.ac.at

SIMBAD Objects

© ESO 2003