_version_ 1866910038903226368
author Venn, Kim A.
Yuan, Zhen
Martin, Nicolas F.
Dovgal, Anya
Zaremba, Daria
Starkenburg, Else
Gran, Felipe
Hayes, Christian R.
Hill, Vanessa
Kobayashi, Chiaki
Lardo, Carmela
McConnachie, Alan W.
Matsuno, Tadafumi
Montelius, Martin
Placco, Vinicius
Sestito, Federico
Ardern-Arentsen, Anke
Battaglia, Guiseppina
Bonifacio, Piercarlo
Carlberg, Raymond
Fabbro, Sebastien
Fouesneau, Morgan
Ibata, Rodrigo
Jablonka, Pascale
Jensen, Jaclyn
Kordopatis, Georges
McKenzie, Madelyn
Navarro, Julio F.
Pazder, John S.
Sanchez-Janssen, Ruben
Smith, Simon T. E.
Viswanathan, Akshara
Vitali, Sara
Wang, Long
Wang, Zhen
author_facet Venn, Kim A.
Yuan, Zhen
Martin, Nicolas F.
Dovgal, Anya
Zaremba, Daria
Starkenburg, Else
Gran, Felipe
Hayes, Christian R.
Hill, Vanessa
Kobayashi, Chiaki
Lardo, Carmela
McConnachie, Alan W.
Matsuno, Tadafumi
Montelius, Martin
Placco, Vinicius
Sestito, Federico
Ardern-Arentsen, Anke
Battaglia, Guiseppina
Bonifacio, Piercarlo
Carlberg, Raymond
Fabbro, Sebastien
Fouesneau, Morgan
Ibata, Rodrigo
Jablonka, Pascale
Jensen, Jaclyn
Kordopatis, Georges
McKenzie, Madelyn
Navarro, Julio F.
Pazder, John S.
Sanchez-Janssen, Ruben
Smith, Simon T. E.
Viswanathan, Akshara
Vitali, Sara
Wang, Long
Wang, Zhen
contents 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.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02445
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The primordial nature of the C-19 stellar stream
Venn, Kim A.
Yuan, Zhen
Martin, Nicolas F.
Dovgal, Anya
Zaremba, Daria
Starkenburg, Else
Gran, Felipe
Hayes, Christian R.
Hill, Vanessa
Kobayashi, Chiaki
Lardo, Carmela
McConnachie, Alan W.
Matsuno, Tadafumi
Montelius, Martin
Placco, Vinicius
Sestito, Federico
Ardern-Arentsen, Anke
Battaglia, Guiseppina
Bonifacio, Piercarlo
Carlberg, Raymond
Fabbro, Sebastien
Fouesneau, Morgan
Ibata, Rodrigo
Jablonka, Pascale
Jensen, Jaclyn
Kordopatis, Georges
McKenzie, Madelyn
Navarro, Julio F.
Pazder, John S.
Sanchez-Janssen, Ruben
Smith, Simon T. E.
Viswanathan, Akshara
Vitali, Sara
Wang, Long
Wang, Zhen
Astrophysics of Galaxies
Solar and Stellar Astrophysics
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.
title The primordial nature of the C-19 stellar stream
topic Astrophysics of Galaxies
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2603.02445