Astrophysical Parameters of 5056 Open Star Clusters from Bayesian Nested Sampling with PARSEC Isochrones
Abstract
We present a homogeneous catalogue of ages, metallicities, distances, and reddenings for 5056 open clusters in the Unified Cluster Catalogue (UCC), derived uniformly from Gaia Data Release 3 (DR3) colour-magnitude diagrams via Bayesian nested sampling with PARSEC isochrones. Unlike previous large-scale catalogues, metallicity is fitted as a free parameter for every cluster rather than fixed or adopted from the literature: where available, Gaia XP spectrophotometric metallicities inform the fit (1201 clusters), while the remaining clusters are constrained by broad priors from Gaia parallaxes and the Schlegel-Finkbeiner-Davis dust map. No cluster is anchored to an external open-cluster parameter catalogue, and no per-cluster manual intervention is applied. A fit-quality metric, ηfit, identifies 3807 clusters (75 per cent) with reliable colour-magnitude solutions, spanning ages of 0.004-5.9 Gyr and distances out to 17 kpc. We validate the resulting parameters against six literature catalogues and, more critically, against independent high-resolution spectroscopic metallicities from OCCAM DR19: for 132 clusters in common we find a median absolute deviation of only 0.054 dex (−0.021 ± 0.132 dex mean offset), comparable to the intrinsic systematic uncertainty of isochrone-based metallicities. As a direct consequence of this fidelity, the radial metallicity gradient recovered from our XP-informed clusters (−0.064 dex kpc−1) steepens towards the spectroscopically calibrated value (−0.079 dex kpc−1) for the highest-quality subset - demonstrating that a purely photometric pipeline, built without reference to spectroscopy, recovers a physically meaningful abundance scale. The full catalogue and posterior chains are publicly released.
Related
- Honoring Paris Pişmiş' Legacy: Uniform Astrophysical Properties of 14 Understudied Clusters from Gaia DR3
- LACHESIS: Robust stellar parameters through Bayesian model averaging of isochrone grids
- A Hierarchical Bayesian Differential Calibration of the Gaia DR3 Parallax Zero Point Using Galactic Globular Clusters
- Isochrones in primordial magnetic field evolution
- Fast and Flow-rious: Gravitational Wave Background Bayesian Model Comparison using Normalizing Flows and Nested Sampling
BibTeX
@misc{plevne2026astrophysical,
title = {{Astrophysical Parameters of 5056 Open Star Clusters from Bayesian Nested Sampling with PARSEC Isochrones}},
author = {Olcay Plevne and Furkan Akbaba},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2605.23802},
eprint = {2605.23802},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.23802},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Astrophysical Parameters of 5056 Open Star Clusters from Bayesian Nested Sampling with PARSEC Isochrones
AU - Olcay Plevne
AU - Furkan Akbaba
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2605.23802
UR - https://arxiv.org/abs/2605.23802
AB - We present a homogeneous catalogue of ages, metallicities, distances, and reddenings for 5056 open clusters in the Unified Cluster Catalogue (UCC), derived uniformly from Gaia Data Release 3 (DR3) colour-magnitude diagrams via Bayesian nested sampling with PARSEC isochrones. Unlike previous large-scale catalogues, metallicity is fitted as a free parameter for every cluster rather than fixed or adopted from the literature: where available, Gaia XP spectrophotometric metallicities inform the fit (1201 clusters), while the remaining clusters are constrained by broad priors from Gaia parallaxes and the Schlegel-Finkbeiner-Davis dust map. No cluster is anchored to an external open-cluster parameter catalogue, and no per-cluster manual intervention is applied. A fit-quality metric, η_fit, identifies 3807 clusters (75 per cent) with reliable colour-magnitude solutions, spanning ages of 0.004-5.9 Gyr and distances out to 17 kpc. We validate the resulting parameters against six literature catalogues and, more critically, against independent high-resolution spectroscopic metallicities from OCCAM DR19: for 132 clusters in common we find a median absolute deviation of only 0.054 dex (−0.021 ± 0.132 dex mean offset), comparable to the intrinsic systematic uncertainty of isochrone-based metallicities. As a direct consequence of this fidelity, the radial metallicity gradient recovered from our XP-informed clusters (−0.064 dex kpc^−1) steepens towards the spectroscopically calibrated value (−0.079 dex kpc^−1) for the highest-quality subset - demonstrating that a purely photometric pipeline, built without reference to spectroscopy, recovers a physically meaningful abundance scale. The full catalogue and posterior chains are publicly released.
ER -