Fitting Isochrones to Open Cluster photometric data: A new global optimization tool

Abstract

We present a new technique to fit color-magnitude diagrams of open clusters based on the Cross-Entropy global optimization algorithm. The method uses theoretical isochrones available in the literature and maximizes a weighted likelihood function based on distances measured in the color-magnitude space. The weights are obtained through a non parametric technique that takes into account the star distance to the observed center of the cluster, observed magnitude uncertainties, the stellar density profile of the cluster among others. The parameters determined simultaneously are distance, reddening, age and metallicity. The method takes binary fraction into account and uses a Monte-Carlo approach to obtain uncertainties on the determined parameters for the cluster by running the fitting algorithm many times with a re-sampled data set through a bootstrapping procedure. We present results for 9 well studied open clusters, based on 15 distinct data sets, and show that the results are consistent with previous studies. The method is shown to be reliable and free of the subjectivity of most previous visual isochrone fitting techniques.

19 pages, 25 figures, accepted for publication in Astronomy&Astrophysics

References in corpus (3)

• A maximum likelihood method for fitting colour-magnitude diagrams
• On the current status of open-cluster parameters
• A robust statistical estimation of the basic parameters of single stellar populations. I. Method

Cited by in corpus (31)

• Painting a portrait of the Galactic disc with its stellar clusters
• UPMASK: unsupervised photometric membership assignment in stellar clusters
• ASteCA - Automated Stellar Cluster Analysis
• Evolution of Mass Functions of Coeval Stars through Wind Mass Loss and Binary Interactions
• Parsec-scale jet precession in BL Lacertae (2200+420)
• A Deep View of a Fossil Relic in the Galactic Bulge: The Globular Cluster HP1
• Accurate age determinations of several nearby open clusters containing magnetic Ap stars
• Models for the 3-D axisymmetric gravitational potential of the Milky Way Galaxy - A detailed modelling of the Galactic disk
• Self-consistent physical parameters for five intermediate-age SMC stellar clusters from CMD modelling
• Reanalysis of nearby open clusters using Gaia DR1/TGAS and HSOY
• Self-consistent analysis of stellar clusters: An application to HST data of the halo globular cluster NGC 6752
• Star clusters or asterisms? 2MASS CMD and structural analyses of 15 challenging targets
• Young and embedded clusters in Cygnus-X: evidence for building up the IMF?
• Radial velocities and metallicities from infrared Ca II triplet spectroscopy of open clusters: Berkeley 26, Berkeley 70, NGC 1798, and NGC 2266
• MiMO: Mixture Model for Open Clusters in Color-Magnitude Diagrams
• Open clusters and associations in the Gaia era
• Exploring the differences of integrated and spatially resolved analysis using integral field unit data: The case of Abell 14
• Probing the anomalous extinction of four young star clusters: the use of colour-excess, main sequence fitting and fractal analysis
• A revisited study of Cepheids in open clusters in the Gaia era
• Fitting isochrones to open cluster photometric data III. Estimating metallicities from UBV photometry
• ALiCCE: Atomic Lines Calibration using the Cross-Entropy Algorithm
• The OPD Photometric Survey of Open Clusters II. robust determination of the fundamental parameters of 24 open clusters
• Bayesian isochrone fitting and stellar ages
• The possibility of determining open-cluster parameters from BVRI photometry
• Vilnius Photometry and Gaia Astrometry of Melotte 105
• Modeling very long baseline interferometric images with the cross-entropy global optimization technique
• Asteroseismic age constraints on the open cluster NGC 2477 using oscillating stars identified with TESS FFI
• Kinematic study of the parsec-scale jet of the quasar PKS 1741--03
• Open Clusters as Probes of the Galactic Magnetic Field: I. Cluster Properties
• New age-metallicity diagnostic diagram for the Washington photometric system
• Exploration about the origin of galactic and extragalactic star clusters through simulated H-R diagrams