Enrichment by Extragalactic First Stars in the Large Magellanic Cloud

Abstract

The Large Magellanic Cloud (LMC) is the Milky Way's most massive satellite galaxy, which only recently (~2 billion years ago) fell into our Galaxy. Since stellar atmospheres preserve their natal cloud's composition, the LMC's recent infall makes its most ancient, metal-deficient ("low-metallicity") stars unique windows into early star formation and nucleosynthesis in a formerly distant region of the high-redshift universe. Previously, identifying such stars in the LMC was challenging. But new techniques have opened this window, now enabling tests of whether the earliest element enrichment and star formation in distant, extragalactic proto-galaxies deviated from what occurred in the proto-Milky Way. Here we present the elemental abundances of 10 stars in the LMC with iron-to-hydrogen ratios ranging from ~1/300th to ~1/12,000th of the Sun. Our most metal-deficient star is 50 times more metal-deficient than any in the LMC with available detailed chemical abundance patterns, and is likely enriched by a single extragalactic first star supernova. This star lacks significant carbon-enhancement, as does our overall sample, in contrast with the lowest metallicity Milky Way stars. This, and other abundance differences, affirm that the extragalactic early LMC experienced diverging enrichment processes compared to the early Milky Way. Early element production, driven by the earliest stars, thus appears to proceed in an environment-dependent manner.

The final version of this paper has been published in Nature Astronomy on March 20, 2024 at https://www.nature.com/articles/s41550-024-02223-w. Free read-only access at https://rdcu.be/dBRPn. The arxiv version is the submitted manuscript, but we note arXiv:2312.12793

References in corpus (26)

• Gaia Data Release 3: Summary of the content and survey properties
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The Dartmouth Stellar Evolution Database
• Are the Magellanic Clouds on their First Passage about the Milky Way?
• An extremely primitive halo star
• Carbon-Enhanced Metal-Poor Star Frequencies in the Galaxy: Corrections for the Effect of Evolutionary Status on Carbon Abundances
• CH in stellar atmospheres: an extensive linelist
• Observational Constraints on First-Star Nucleosynthesis. I. Evidence for Multiple Progenitors of CEMP-no Stars
• Complete element abundances of nine stars in the r-process galaxy Reticulum II
• Line lists for the A2PI-X2Sigma+ (red) and {B2Sigma+-X2Sigma} (violet) Systems of CN, 13C14N, and 12C15N, and Application to Astronomical Spectra
• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
• The $R$-Process Alliance: Fourth Data Release from the Search for $r$-Process-Enhanced Stars in the Galactic Halo
• $S^5$: Probing the Milky Way and Magellanic Clouds potentials with the 6-D map of the Orphan-Chenab stream
• Gaia Data Release 3: The Galaxy in your preferred colours. Synthetic photometry from Gaia low-resolution spectra
• The R-process Alliance: First Magellan/MIKE Release from the Southern Search for R-Process-enhanced Stars
• The Southern Stellar Stream Spectroscopic Survey (S5): Chemical Abundances of Seven Stellar Streams
• The first stars: CEMP--no stars and signatures of spinstars
• Predicting the locations of possible long-lived low-mass first stars: Importance of satellite dwarf galaxies
• Detailed Abundances in the Ultra-faint Magellanic Satellites Carina II and III
• The Atari Disk, a Metal-Poor Stellar Population in the Disk System of the Milky Way
• Stellar metallicities from SkyMapper photometry I: A study of the Tucana II ultra-faint dwarf galaxy
• Detailed chemical abundances of stars in the outskirts of the Tucana II ultra-faint dwarf galaxy
• The chemical abundance pattern of the extremely metal-poor thin disk star 2MASS J1808-5104 and its origins
• Tracing Pop III supernovae with extreme energies through the Sculptor dwarf spheroidal galaxy
• The SkyMapper search for extremely metal-poor stars in the Large Magellanic Cloud
• Formation and fate of low metallicity stars in IllustrisTNG50

Cited by in corpus (8)

• Discovery of an $[Fe/H]\sim -4.8$ Star in $Gaia$ XP Spectra
• The Pristine Inner Galaxy Survey (PIGS) X. Probing the early chemical evolution of the Sagittarius dwarf galaxy with carbon abundances
• Mapping the Distant and Metal-Poor Milky Way with SDSS-V
• A second-generation star in a relic dwarf galaxy
• Cosmological insights into the early accretion of r-process-enhanced stars II. Dynamical identification of lost members of Reticulum II
• The chemical DNA of the Magellanic Clouds V. R-process dominates neutron capture elements production in the oldest SMC stars
• HE0144-4657: A Carbon-Enhanced Ultra Metal-Poor Star ([Fe/H] ~ -4.1) from the Helmi Stream Disrupted Dwarf Galaxy
• The metal-poor tail of the APOGEE survey I. Uncovering [Fe/H] < -2.5 stars from the inner Galaxy to the Magellanic Clouds