Extracting parameters from Colour-Magnitude Diagrams

Abstract

We present a simple approach for obtaining robust values of astrophysical parameters from the observed colour-magnitude diagrams (CMDs) of star clusters. The basic inputs are the Hess diagram built with the photometric measurements of a star cluster and a set of isochrones covering wide ranges of age and metallicity. In short, each isochrone is shifted in apparent distance modulus and colour excess until it crosses over the maximum possible Hess density. Repeating this step for all available isochrones leads to the construction of the solution map, in which the optimum values of age and metallicity - as well as foreground/background reddening and distance from the Sun - can be searched for. Controlled tests with simulated CMDs show that the approach is efficient in recovering the input values. We apply the approach to the open clusters M\,67, NGC\,6791, and NGC\,2635, which are characterised by different ages, metallicities and distances from the Sun.

arXiv commentAccepted by MNRAS

References in corpus (22)

• On the variation of the Initial Mass Function
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Embedded Clusters in Molecular Clouds
• Improving PARSEC models for very low mass stars
• Gas expulsion and the destruction of massive young clusters
• A white dwarf cooling age of 8 Gyr for NGC 6791 from physical separation processes
• Clusters in the solar neighbourhood: how are they destroyed?
• A maximum likelihood method for fitting colour-magnitude diagrams
• Ground-based CCD astrometry with wide field imagers. II. A star catalogue for M67: [email protected] MPG/ESO astrometry, FLAMES@VLT radial velocities
• Mass loss rates and the mass evolution of star clusters
• Isochrones for Old (> 5 Gyr) Stars and Stellar Populations. I. Models for $-2.4\le$ [Fe/H] $\le +0.6$, $0.25\le Y\le 0.33$, and $-0.4\le$ [$\alpha$\Fe] $\le +0.4$
• Inverting Color-Magnitude Diagrams to Access Precise Star Cluster Parameters: A Bayesian Approach
• Deep 2MASS Photometry of M67 and Calibration of the Main Sequence J-Ks Color Difference as an Age Indicator
• The effect of the dynamical state of clusters on gas expulsion and infant mortality
• Constraining the star formation rate in the Solar neighbourhood with star clusters
• A New Method for the Assessment of Age and Age-Spread of Pre-Main Sequence Stars in Young Stellar Associations of the Magellanic Clouds
• Analysis of colour-magnitude diagrams of rich LMC clusters: NGC 1831
• Statistical analysis of stellar evolution
• Towards a census of the Galactic anticentre star clusters - III: tracing the spiral structure in the Outer Disk
• Multichromatic colour-magnitude diagrams of the globular cluster NGC 6366
• NGC 2401: A template of the Norma-Cygnus Arm's young population in the Third Galactic Quadrant
• Unveiling hidden properties of young star clusters: differential reddening, star-formation spread and binary fraction

Cited by in corpus (6)

• Ultraviolet stellar population of the old open cluster M67 (NGC 2682)
• The $Gaia$-ESO Survey: the inner disk intermediate-age open cluster NGC 6802
• UOCS. III. UVIT catalogue of open clusters with machine learning based membership using \textit{Gaia} EDR3 astrometry
• Ensemble Properties of the White Dwarf Population of the Old, Solar Metallicity Open Star Cluster Messier 67
• The White Dwarfs of the Old, Solar Metallicity Open Star Cluster Messier 67: Properties and Progenitors
• The Initial-Final Mass Relation for Hydrogen-Deficient White Dwarfs