NGC 2660: Gaia DR2, ASteCA and the end of controversies?

PERREN, G. I.; PERA, M.S.; GIORGI, E. E.; SOLIVELLA, G. R.; VÁZQUEZ R. A.; DE LAURENTI, M. A.; CRUZADO, A.

Rosario

Congreso; 62 Reunión Anual de la Asociación Argentina de Astronomía; 2020

Universidad Nacional de Rosario

NGC 2660, an old and very compact open cluster placed at about 3 kpc from the Sun in a region ofmoderate absorption, has been subject of several photometric and spectroscopic studies in the past. Controversies arise in terms of its distance, age and metal content. Previous comparisons with cluster synthetic models carried out did not resolve them. We decided to analyze this object combining high precision parallax, proper motions and magnitudes coming from the Gaia Second Data release (Gaia DR2), in order to improve the cluster fundamental parameters. So we collect Gaia DR2 data in region 1 deg on a side, centered in NGC 2660. For the membership estimation, we run the pyUPMASK code and completed the overall cluster analysis with the ASteCA code. The cluster main sequence shows a well-defined turn-off point although some stars are placed above it, resembling the typical position of blue straggler stars. There is an evident widening of the main sequence hard to be explained by just photometric errors becoming more probable that it is produced by a high percentage of binary stars.