A baseline on the relation between chemical patterns and the birth stellar cluster

¹ Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
e-mail: theosamuele.signor@mail.udp.cl
² Inria Chile Research Center, Av. Apoquindo 2827, Piso 12, Las Condes, Santiago, Chile
³ Millenium Nucleus ERIS, Chile

Received: 11 March 2024
Accepted: 22 May 2024

Abstract

Context. The chemical composition of a star’s atmosphere reflects the chemical composition of its birth environment. Therefore, it should be feasible to recognize stars born together that have scattered throughout the galaxy, solely based on their chemistry. This concept, known as “strong chemical tagging”, is a major objective of spectroscopic studies, but it has yet to yield the anticipated results.

Aims. We assess the existence and the robustness of the relation between chemical abundances and the birthplace using known member stars of open clusters.

Methods. We followed a supervised machine learning approach, using chemical abundances obtained from APOGEE DR17, observed open clusters as labels, and different data preprocessing techniques.

Results. We find that open clusters can be recovered with any classifier and on data whose features are not carefully selected. In the sample with no field stars, we obtain an average accuracy of 75.2% and we find that the prediction accuracy mostly depends on the uncertainties of the chemical abundances. When field stars outnumber the cluster members, the performance degrades.

Conclusions. Our results show the difficulty of recovering birth clusters using chemistry alone, even in a supervised scenario. This clearly challenges the feasibility of strong chemical tagging. Nevertheless, including information about ages could potentially enhance the possibility of recovering birth clusters.