Variable stars in the field of the old open cluster Melotte 66

Abstract

We report the results of photometric monitoring of the Melotte 66 field in BVI filters. Ten variables were identified with nine being new discoveries. The sample includes eight eclipsing binaries of which four are W UMa type stars, one star is a candidate blue straggler. All four contact binaries are likely members of the cluster based on their estimated distances. Ten blue stars with U-B<-0.3 were detected inside a 14.8 x 22.8 arcmin^2 field centred on the cluster. Time series photometry for 7 of them showed no evidence for any variability. The brightest object in the sample of blue stars is a promising candidate for a hot subdwarf belonging to the cluster. We show that the anomalously wide main sequence of the cluster, reported in some earlier studies, results from a combination of two effects: variable reddening occuring across the cluster field and the presence of a rich population of binary stars in the cluster itself. The density profile of the cluster field is derived and the total number of member stars with 16<V<21 or 2.8<M_{V}<7.8 is estimated conservatively at about 1100.

arXiv comment8 pages, 12 figures, accepted to MNRAS - 29 June 2007

References in corpus (12)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• A method for optimal image subtraction
• Homogeneous Photometry for Star Clusters and Resolved Galaxies. II. Photometric Standard Stars
• The Carnegie Supernova Project: The Low-Redshift Survey
• Hot subdwarfs from the ESO Supernova Ia Progenitor Survey - I. Atmospheric parameters and cool companions of sdB stars
• Contact Binaries of the Galactic Disk: Comparison of the Baade's Window and Open Cluster Samples
• W UMa-type Binary Stars in Globular Clusters
• Spectroscopic Analyses of the Blue Hook Stars in NGC 2808: A More Stringent Test of the Late Hot Flasher Scenario
• Luminosity function of contact binaries based on the ASAS survey
• Planets in Stellar Clusters Extensive Search. IV. A detection of a possible transiting planet candidate in the open cluster NGC 2158
• Spectroscopic Analyses of the "Blue Hook" Stars in omega Centauri: A Test of the Late Hot Flasher Scenario
• Efficient analysis in planet transit surveys

Cited by in corpus (6)

• Contact Binaries as Viable Distance Indicators: New, Competitive (V)JHKs Period-Luminosity Relations
• Rotational and Radial Velocities of 1.3-2.2 M_Sun Red Giants in Open Clusters
• Characterization of hot populations of Melotte 66 open cluster using Swift/UVOT
• Updated properties of the old open cluster Melotte 66: Searching for multiple stellar populations
• Variable Stars in the Field of the Open Cluster NGC 2126
• Signatures of Extended Dark Energy Parametrisations in Structure Formation under Background Constraints