The primordial nature of the C-19 stellar stream
Abstract
Stellar streams, remnants of compact star systems stretched out by the tidal forces of the Milky Way, offer a unique way to study stellar populations that formed billions of years ago. A particularly unique stream is C-19, the most metal-poor stellar stream known at less than a thousandth of the Sun's metallicity. The nature of C-19 is not yet clear, with properties that resemble both star clusters and ultra faint dwarf galaxies, yet in either case its extremely low metallicity indicates very early star formation, <1 Gyr after the Big Bang. Here, we present the first detailed study on the nature of C-19 based on the chemical abundances of 14 member stars from high-resolution spectroscopy. These reveal that C-19 formed stars in an early, rapid, and prolific star formation event, with mild inhomogeneous mixing of elements produced in massive stars. There is otherwise no evidence for subsequent star formation, multiple stellar populations, nor chemical evolution. Although C-19 is currently disrupted in the Milky Way halo, it offers a rare and complementary window into the details of star formation and chemical evolution in the early universe, ideal for comparisons with current studies of primordial star formation in the high-redshift universe.
Cite
@article{arxiv.2603.02445,
title = {The primordial nature of the C-19 stellar stream},
author = {Kim A. Venn and Zhen Yuan and Nicolas F. Martin and Anya Dovgal and Daria Zaremba and Else Starkenburg and Felipe Gran and Christian R. Hayes and Vanessa Hill and Chiaki Kobayashi and Carmela Lardo and Alan W. McConnachie and Tadafumi Matsuno and Martin Montelius and Vinicius Placco and Federico Sestito and Anke Ardern-Arentsen and Guiseppina Battaglia and Piercarlo Bonifacio and Raymond Carlberg and Sebastien Fabbro and Morgan Fouesneau and Rodrigo Ibata and Pascale Jablonka and Jaclyn Jensen and Georges Kordopatis and Madelyn McKenzie and Julio F. Navarro and John S. Pazder and Ruben Sanchez-Janssen and Simon T. E. Smith and Akshara Viswanathan and Sara Vitali and Long Wang and Zhen Wang},
journal= {arXiv preprint arXiv:2603.02445},
year = {2026}
}
Comments
13 pages, 6 figures, under review - comments welcome