Empirical Isochronous Curves for Open Clusters in the Mv vs (V-I)o Plane

PIATTI, ANDRÉS E.; CLARIA OLMEDO, JUAN JOSÉ; BICA, EDUARDO

San Juan

Congreso; Reunión Anual de la Asoc. Argentina de Astronomía; 1997

New CCD VI photometric data for 10 template open clusters with accurately determined fundamental parameters are presented. From the observed V vs V-I diagrams of the clusters, fiducial sequences have been defined and transformed into the Mv vs (V-I)o diagram by averaging sequences of template open clusters with similar ages. The resulting composite Mv vs (V-I)o diagram presents a homogeneous set of empirical isochronous curves in the age range between 5 Myr and 4 Gyr. These empirical isochrones show an overall very good agreement with those computed from stellar evolutionary models. Theoretical isochrones with moderate overshooting fit the observed main sequences better than the canonical ones for clusters older than 600 Myr.