A wide angle view of the Sagittarius dwarf spheroidal galaxy

II. A CEMP-r/s star in the Sagittarius dwarf spheroidal galaxy^⋆,⋆⋆

¹ ESO – European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
e-mail: lsbordon@eso.org
² Max Planck Institute for Astronomy, Heidelberg, Königstuhl 17, 69117 Heidelberg, Germany
³ Departamento de Ciencias Fisicas, Universidad Andres Bello, Fernandez Concha 700, Las Condes, Santiago, Chile
⁴ INAF – Osservatorio Astronomico d’Abruzzo, Via Maggini snc, Teramo, Italy
⁵ INFN – Sezione di Perugia, Via A. Pascoli, Perugia, Italy
⁶ GEPI, Observatoire de Paris, Université PSL, CNRS, Place Jules Janssen, 92195 Meudon, France
⁷ Departamento de Astronomía, Universidad de Concepción, Casilla 160-C, Concepción, Chile
⁸ Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Avenida Padre Hurtado 750, Viña del Mar 2520000, Chile

Received: 8 March 2020
Accepted: 5 May 2020

Abstract

We report on the discovery and chemical abundance analysis of the first CEMP-r/s star detected in the Sagittarius dwarf spheroidal galaxy (Sgr dSph) by means of UVES high-resolution spectra. The star, found in the outskirts of Sgr dSph, along the major axis of the main body, is a moderately metal-poor giant (T_eff = 4753 K, log g = 1.75, [Fe/H] = −1.55) with [C/Fe] = 1.13, placing it in the so-called “high-carbon band”, and strong s-process and r-process enrichment ([Ba/Fe] = 1.4, [Eu/Fe] = 1.01). Abundances of 29 elements from C to Dy were obtained. The chemical pattern appears to be best fitted by a scenario where an r-process pollution event pre-enriched the material out of which the star was born as secondary in a binary system whose primary evolved through the AGB phase, providing C- and s-process enrichment.