GHOST Commissioning Science Results: Identifying a New Chemically Peculiar Star in Reticulum II
Abstract
The Gemini High-resolution Optical SpecTrograph (GHOST) is the newest high-resolution spectrograph to be developed for a large-aperture telescope, recently deployed and commissioned at the Gemini-South telescope. In this paper, we present the first science results from the GHOST spectrograph taking during its commissioning runs. We have observed the bright metal-poor benchmark star HD 122563, along with two stars in the ultrafaint dwarf galaxy Reticulum II (Ret II), one of which was previously identified as a candidate member, but did not have a previous detailed chemical abundance analysis. We find that this candidate (GDR3 0928) to be a bona fide member of Ret II, and from a spectral synthesis analysis it is also revealed to be a CEMP-r star, with significant enhancements in several light elements (C, N, O, Na, Mg, and Si), in addition to featuring an r-process enhancement like many other Ret II stars. The light-element enhancements in this star resemble the abundance patterns seen in the CEMP-no stars of other ultrafaint dwarf galaxies, and are thought to have been produced by an independent source from the r-process. These unusual abundance patterns are thought to be produced by faint supernovae, which may be produced by some of the earliest generations of stars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2023
- DOI:
- 10.3847/1538-4357/acebc0
- arXiv:
- arXiv:2306.04804
- Bibcode:
- 2023ApJ...955...17H
- Keywords:
-
- Dwarf galaxies;
- Chemically peculiar stars;
- Chemical abundances;
- High resolution spectroscopy;
- Observational astronomy;
- 416;
- 226;
- 224;
- 2096;
- 1145;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 23 pages, 9 figures, 7 tables, submitted to the AAS Journals