The OPD Photometric Survey of Open Clusters II. robust determination of the fundamental parameters of 24 open clusters

TL;DR

This study uses a robust optimization method to analyze photometric data of 24 open clusters, determining their fundamental parameters with improved accuracy and identifying some as likely asterisms.

Contribution

It introduces a new global optimization approach for fitting isochrones to photometric data and applies it to 24 neglected open clusters, including high-quality new observations.

Findings

14 clusters analyzed with new high-quality data

Two objects identified as likely asterisms

Discrepancies found with previous literature results

Abstract

In the second paper of the series we continue the investigation of open cluster fundamental parameters using a robust global optimization method to fit model isochrones to photometric data. We present optical UBVRI CCD photometry (Johnsons-Cousins system) observations for 24 neglected open clusters, of which 14 have high quality data in the visible obtained for the first time, as a part of our ongoing survey being carried out in the 0.6m telescope of the Pico dos Dias Observatory in Brazil. All objects were then analyzed with a global optimization tool developed by our group which estimates the membership likelihood of the observed stars and fits an isochrone from which a distance, age, reddening, total to selective extinction ratio $R_{V}$ (included in this work as a new free parameter) and metallicity are estimated. Based on those estimates and their associated errors we analyzed the status of each object as real clusters or not, finding that two are likely to be asterisms. We also identify important discrepancies between our results and previous ones obtained in the literature which were determined using 2MASS photometry.