APOGEE chemical abundances of stars in the Milky Way satellites Fornax, Sextans, Draco, and Carina

¹ Department of Astronomy, School of Physics and Astronomy, Sun Yat-sen University, Zhuhai, Guangdong Province, China
² CSST Science Center for the Guangdong-Hong Kong-Macau Greater Bay Area, Zhuhai 519082, China
³ Universidad Católica del Norte, Núcleo UCN en Arqueología Galáctica - Inst. de Astronomía, Av. Angamos 0610, Antofagasta, Chile
⁴ Universidad Católica del Norte, Departamento de Ingeniería de Sistemas y Computación, Av. Angamos 0610, Antofagasta, Chile
⁵ School of Astronomy and Space Science, Nanjing University, Nanjing 210093, PR China
⁶ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
⁷ Departamento de Astronomía, Casilla 160-C, Universidad de Concepción, Concepción, Chile
⁸ Departamento de Astronomía, Facultad de Ciencias, Universidad de La Serena. Av. Raúl Bitrán 1305, La Serena, Chile

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 5 June 2025
Accepted: 12 March 2026

Abstract

During its evolution, the Milky Way (MW) incorporated numerous dwarf galaxies, particularly low-mass systems. The surviving dwarf galaxies orbiting the MW serve as exceptional laboratories for studying the unique properties of these systems. Their metalpoor environments and shallow gravitational potentials likely drive significant differences in star formation and star cluster properties compared to those in the MW. Using high-quality near-infrared spectra from the APOGEE survey, we determined abundances of Fe, C, N, O, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, and Ce for 74 stars in four MW satellite dwarf galaxies: Fornax, Sextans, Draco, and Carina. Our analysis reveals that the distribution of α elements (e.g., [Si/Fe]) strongly correlates with galaxy luminosity (and hence mass), underscoring the critical role of galaxy mass in shaping chemical evolution. These dwarf galaxies exhibit [Al/Fe]~ −0.5, which is comparable to those of the metal-poor stars in the MW. Additionally, we identified nitrogen-rich field stars in the Fornax dwarf galaxy, which display distinct metallicities compared to its known globular clusters (GCs). If these stars originated in GCs and subsequently escaped, their presence suggests we are observing relics of destroyed GCs, offering possible evidence of cluster disruption.