Not-so-heavy metal(s): Chemical Abundances in the Ultra-faint Dwarf Galaxies Eridanus IV and Centaurus I

Mairéad E Heiger; Alexander P Ji; Ting S Li; Joshua D Simon; Guilherme Limberg; Julio A Carballo-Bello; William Cerny; Astha Chaturvedi; Anirudh Chiti; Yumi Choi; Denija Crnojević; Clara E Martínez-Vázquez; Gustavo E Medina; Burçin Mutlu-Pakdil; Mahdieh Navabi; Noelia E D Noël; Andrew B Pace; Vinicius M Placco; Alexander H Riley; Joanna D Sakowska; Guy S Stringfellow

arXiv · 2508.11012

Not-so-heavy metal(s): Chemical Abundances in the Ultra-faint Dwarf Galaxies Eridanus IV and Centaurus I

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Abstract

We present detailed chemical abundances of the brightest star in each of the ultra-faint dwarf galaxies Eridanus IV and Centaurus I using high-resolution Magellan/MIKE spectroscopy. The brightest star in Centaurus I, CenI-5136, is a very metal-poor star with metallicity [Fe/H] = $-2.52\pm0.17$ and chemical abundances typical of a star in an ultra-faint dwarf galaxy. We confirm that the star in Eridanus IV, EriIV-9808, is extremely metal-poor ([Fe/H] = $-3.25\pm0.19$) and find that it is carbon-enhanced, with [C/Fe] = $1.07\pm0.34$, as is common for many stars at this metallicity. Both stars are also neutron-capture deficient, which is typical of stars in ultra-faint dwarf galaxies, but less common in other environments. We consider possible enrichment scenarios for EriIV-9808 and tentatively conclude that it is unlikely to be the descendant of a single Pop III progenitor, despite its carbon-enhancement and low metallicity.

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Mairéad E Heiger, Alexander P Ji, Ting S Li, Joshua D Simon, Guilherme Limberg, Julio A Carballo-Bello, William Cerny, Astha Chaturvedi, Anirudh Chiti, Yumi Choi, Denija Crnojević, Clara E Martínez-Vázquez, Gustavo E Medina, Burçin Mutlu-Pakdil, Mahdieh Navabi, Noelia E D Noël, Andrew B Pace, Vinicius M Placco, Alexander H Riley, Joanna D Sakowska, Guy S Stringfellow. 2025-08-14. Not-so-heavy metal(s): Chemical Abundances in the Ultra-faint Dwarf Galaxies Eridanus IV and Centaurus I. https://arxiv.org/abs/2508.11012

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