Journal Article

Photometric study and detection of variable stars in the open clusters – I. NGC 6866

Y. C. Joshi, S. Joshi, Brijesh Kumar, Soumen Mondal and L. A. Balona

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 419, issue 3, pages 2379-2390
Published in print January 2012 | ISSN: 0035-8711
Published online January 2012 | e-ISSN: 1365-2966 | DOI:
Photometric study and detection of variable stars in the open clusters – I. NGC 6866

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We present results of a variability search in the intermediate-age open cluster NGC 6866 from 29 nights over two observing seasons. We find 28 periodic variables, of which 19 are newly identified. The periods of these variables, which have V magnitudes from 11.5 to 19.3 mag, range from ∼48 min to 37 d. We detected several δ Scuti stars, some of which are of high amplitude, as well as γ Doradus and rotational variables, and eclipsing binaries. In order to study the physical properties of the cluster, we obtained UBVRI photometry of all the stars on a good photometric night. The radial distribution of the stellar surface density shows that the cluster has a radial extent of about 7 arcmin (∼3 pc) with a peak density of 5.7 ± 0.7 stars arcmin−2 at the cluster centre. The colour–colour diagram indicates a reddening of E(BV) = 0.10 mag towards NGC 6866. A distance of ∼1.47 kpc and an age of ∼630 Myr are estimated from the colour–magnitude diagram using the theoretical isochrones of solar metallicity.

Keywords: techniques: photometric; stars: variables: general; open clusters and associations: individual: NGC 6866

Journal Article.  7246 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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