Chemical analysis of evolved stars with brown dwarfs from Gemini-GRACES spectra

CAMILA ZULOAGA; EMILIANO JOFRÉ; ROMINA PETRUCCI; EDER MARTIOLI

Córdoba

Congreso; XII Friends of Friends Meeting; 2023

Observatorio Astronómico - Universidad Nacional de Córdoba

Main sequence (MS) stars with short-period giant planets are more metal rich than those without planets (e.g., Fischer & Valenti 2005). This is known as the “planet-metallicity’’ correlation (PMC). This relation is not satisfied in giant stars with planets (e.g., Jofré et al. 2010, 2015a) and, recently, it has been suggested that MS stars with brown dwarfs (BD) do not follow this correlation either (e.g., Maldonado et al. 2017). However, the role of metallicity in the formation of BD around MS stars that are more massive than FGK stars, which are the progenitors of the red giants included in the radial velocity (VR) planet search surveys, is not well understood. Additionally, precise spectroscopic analysis of evolved stars has allowed the discovery of chemical anomalies (e.g., excess in lithium, alpha elements, and iron peak elements) that could be related to external contamination events (e.g., substellar companion accretion, type II supernovae; Jofré et al. 2015b). Moreover, high-precision spectroscopic stellar parameters are key to refine the properties of the substellar companions (see e.g., Sousa et al. 2015, Jofré et al. 2020, 2021). In this context, we present a spectroscopic detailed analysis of two K red giants, which harbor BD: HD 54719 and HD 180314.