SCYON Abstract

Received on May 31 2007

uvby-Hβ CCD photometry and membership segregation of the open cluster NGC 2682 (M 67).

AuthorsLola Balaguer-Núñez (1,2,3), David Galadí-Enríquez (4), and Carme Jordi (1,5)
Affiliation(1) UB, Spain
(2) SHAO, China
(3) IoA, Cambridge, UK
(4) IAA (CSIC), Spain
(5) IEEC, Spain
Accepted byAstronomy & Astrophysics
Contactlola.balaguer@am.ub.es
URLhttp://es.arxiv.org/abs/0704.2887
Links M67

Abstract

Following deep astrometric and photometric study of the cluster NGC 2682 (M67), we are able to accurately determine its fundamental parameters. Being an old and rich cluster, M67 is a relevant object for the analysis of the Galactic disk evolution. M67 is well studied but the lack of a wide and deep Stromgren photometric study makes our results worthwhile. The brightest stars of the open cluster M67 were used as uvby-Hbeta standard stars in our studies of NGC 1817 and NGC 2548, and the extension of the field covered, as well as the amount of observations, allowed to obtain the best set of Stromgren data ever published for this cluster. We discuss the results of our CCD uvby-Hbeta intermediate-band photometry, covering an area of about 50'x50' down to V 19. Moreover, a complete membership segregation based on astrometric and photometric criteria is obtained. The photometric analysis of a selected sample of stars yields a reddening value of E(b-y) = 0.03±0.03, a distance modulus of V0-MV = 9.7±0.2 and [Fe/H] = 0.01±0.14. Through isochrone fitting we found an age of log t = 9.6±0.1 (4.2±0.2 Gyr). A clump of approximately 60 stars around V = 16, (b-y)= 0.4 could be interpreted as a population of pre-cataclysmic variable stars (if members), or as a stream of field G-type stars placed at twice the distance of the cluster (if non-members).