HD 150382: A Lithium-rich Star at the Early-AGB Stage?

Abstract

We report the discovery of a lithium-rich giant, HD 150382, a post-red-giant-branch clump star. The atmospheric parameters, the chemical abundances for 17 elements, and the isotopic ratio ¹²C/¹³C were determined using the equivalent width and the spectral synthesis methods. The lithium abundance was determined via spectral synthesis of the Li I resonance doublet at λ 6708 yielding log ɛ(Li)_NLTE = 2.55. The excited-state line at λ 6104 also was analyzed. In addition, we have used theoretical evolutionary tracks to determine the mass and luminosity of HD 150382 and compare it with other well-known lithium-rich giants in the literature. Our results show that HD 150382 is a slowly rotating K-giant star having near-solar metallicity. We also show that HD 150382 is not s-process enriched, which is in agreement with its evolutionary status. Finally, based on the abundance results, we study the possible scenarios of the lithium enrichment.

Based on the observations made with the 2.2 m telescope at the European Southern Observatory (La Silla, Chile) under the agreement with Observatório Nacional and under agreement between Observatório Nacional and Max-Planck Institute für Astronomie.