One Star to Tag Them All (OSTTA)

I. Radial velocities and chemical abundances for 20 poorly studied open clusters^★

¹ INAF - Osservatorio Astronomico di Padova, vicolo Osservatorio 5, 35122 Padova, Italy
e-mail: jimenez.carrera@inaf.it
² Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
³ INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via P Gobetti 93/3, 40129 Bologna, Italy
⁴ Institut de Ciències del Cosmos, Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, 08028 Barcelona, Spain
⁵ INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
⁶ Leibniz-Institute for Astrophysics Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany

Received: 18 January 2022
Accepted: 1 April 2022

Abstract

Context. Open clusters are ideal laboratories to investigate a variety of astrophysical topics, from the properties of the Galactic disc to stellar evolution models. For this purpose, we need to know their chemical composition in detail. Unfortunately, the number of systems with chemical abundances determined from high resolution spectroscopy remains small.

Aims. Our aim is to increase the number of open clusters with radial velocities and chemical abundances determined from high resolution spectroscopy by sampling a few stars in clusters which had not been previously studied.

Methods. We obtained high resolution spectra with the FIbre-fed Echelle Spectrograph at Nordic Optical Telescope for 41 stars belonging to 20 open clusters. These stars have high astrometric membership probabilities determined from the Gaia second data release.

Results. We derived radial velocites for all the observed stars which were used to confirm their membership to the corresponding clusters. For Gulliver 37, we cannot be sure the observed star is a real member. We derived atmospheric parameters for the 32 stars considered to be real cluster members. We discarded five stars because they have very low gravity or their atmospheric parameters were not properly constrained due to low signal-to-noise ratio spectra. Therefore, detailed chemical abundances were determined for 28 stars belonging to 17 clusters. For most of them, this is the first chemical analysis available in the literature. Finally, we compared the clusters in our sample to a large population of well-studied clusters. The studied systems follow the trends, both chemical and kinematical, described by the majority of open clusters. It is worth mentioning that the three most metal-poor studied clusters (NGC 1027, NGC 1750, and Trumpler 2) are enhanced in Si, but not in the other α-elements studied (Mg, Ca, and Ti).