A machine-learning-based tool for open cluster membership determination in Gaia DR3

Astronomy and Astrophysics, vol. 675, pp. A68

Abstract

Context. Membership studies characterising open clusters (OCs) with Gaia data – most of them using Gaia Data Release 2 (DR2) – have so far been limited at the faint end to magnitude G = 18 due to astrometric uncertainties. Aims. Our goal is to extend current OC membership lists with faint members and to characterise the low-mass end. These low-mass members are important for many applications, in particular for ground-based spectroscopic surveys. Methods. We use a deep neural network architecture to learn the distribution of highly reliable OC member stars around known clusters. We then use the trained network to estimate new OC members based on their similarities in a high dimensional space, their five-dimensional astrometry, and information from the three photometric bands. Results. Due to the improved astrometric precision of Gaia Data Release 3 (DR3) with respect to DR2, we are able to homogeneously detect new faint member stars ( G > 18) for the known OC population. Conclusions. Our methodology can provide extended membership lists for OCs down to the limiting magnitude of Gaia , which will enable further studies to characterise the OC population; such as estimation of their masses and dynamics. These extended membership lists are also ideal target lists for forthcoming ground-based spectroscopic surveys.

Authors 5

1. M. G. J. van Groeningen corresponding Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , Niels Bohrweg 2 , 2333 CA Leiden , The Netherlands

   Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, the Netherlands

2. A. Castro-Ginard Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , Niels Bohrweg 2 , 2333 CA Leiden , The Netherlands

   Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, the Netherlands

3. A. G. A. Brown Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , Niels Bohrweg 2 , 2333 CA Leiden , The Netherlands

   Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, the Netherlands

4. L. Casamiquela

   Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Paris Cité · Galaxies, Etoiles, Physique et Instrumentation

   Affiliation as printed

   GEPI , Observatoire de Paris , PSL Research University , CNRS , Sorbonne Paris Cité , 5 place Jules Janssen , 92190 Meudon , France

   GEPI, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Paris Cité, 5 place Jules Janssen, 92190 Meudon, France

5. C. Jordi

   Institut d'Estudis Espacials de Catalunya · Institut de Ciències del Cosmos · Universitat de Barcelona

   Affiliation as printed

   Departament de Física Quàntica i Astrofísica (FQA), Universitat de Barcelona (UB), Martí i Franquès, 1, 08028 Barcelona, Spain

   Institut d'Estudis Espacials de Catalunya (IEEC), Gran Capità, 2-4, 08034 Barcelona, Spain

   Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (UB), Martí i Franquès, 1, 08028 Barcelona, Spain