Heavy Elements in a Swirling Storm: How Neutron Stars Inside Common Envelopes Forge the Universe’s Rarest Atoms
Anninos et al. model how a neutron star inside a common envelope can forge heavy elements as infalling gas heats, cools, and cycles through turbulent convection. Their simulations show that both r-process and rare p-nuclei can form, even in slightly proton-rich conditions, because high entropy and rapid expansion prevent neutrons from being fully locked into alpha particles. Some material escapes the star’s gravity, suggesting CE systems may contribute to the Universe’s heaviest elements.
Tracing Cosmic Origins: Europium in the Small Magellanic Cloud
Anoardo et al. present the first large survey of europium in 209 stars of the Small Magellanic Cloud, tracing how heavy elements formed there. They find the SMC has high [Eu/Mg] ratios, signifying strong r-process enrichment, compared to the Milky Way. This suggests dwarf galaxies produce europium more efficiently due to slower star formation, offering key insight into how such systems contributed heavy elements to our Galaxy.
Tracing the Origins of the Universe’s Heaviest Elements: The R-Process Alliance Examines Ten Ancient Stars
Racca et al. (2025) studied ten ancient, r-process-enriched stars to uncover how the universe creates its heaviest elements. Using high-resolution spectroscopy, they found nearly identical abundance patterns across stars from distinct origins, with minimal variation (<0.1 dex). This surprising uniformity suggests that r-process nucleosynthesis, likely from neutron-star mergers or similar extreme events, follows a consistent, universal mechanism throughout cosmic history.
Mapping the Motion of the Milky Way’s r-Process Stars
Pallavi Saraf and collaborators studied how r-process-enhanced stars, those rich in heavy elements formed by rapid neutron capture, move through the Milky Way. Using Gaia data and orbital simulations, they found these stars are almost evenly split between the disk and halo. Most have uncertain origins, though halo stars are more likely accreted. Similar chemical patterns across regions suggest r-process enrichment occurred under comparable conditions throughout the Galaxy.
Seeing the Hidden Differences: Neutron-Capture Elements in Stellar Doppelgängers
Catherine Manea and collaborators studied “chemical doppelgängers,” stars that look identical in APOGEE survey data. Using high-resolution optical spectra, they found that while these stars match in lighter elements, they often differ in heavier neutron-capture elements like Ba and Eu by up to 140%. This shows APOGEE alone can miss hidden chemical differences, highlighting the need for optical data to fully trace the Milky Way’s history.
A Tenuous Signal: Searching for Heavy Element Dispersion in the Stars of M5
Nalamwar and collaborators studied 28 stars in the globular cluster M5 using Keck spectra to test for r-process variations. They found a small spread in neodymium among first-generation stars but no clear dispersion in europium or second-generation stars. This suggests early, uneven enrichment of heavy elements in M5, possibly from a rare stellar explosion or merging gas clouds, though the evidence remains tentative.
Forging the Light Elements: How Low-Metallicity Novae Could Shape the Early Universe
This study explores how low-metallicity novae—stellar explosions in early, metal-poor environments—can trigger a weak rp-process, producing elements heavier than calcium. Using simulations and Monte Carlo analysis, the authors identify key nuclear reactions and highlight their astrophysical impact. These novae may leave detectable chemical signatures, offering clues to the early Universe’s element formation.
Digging for Cosmic Gold: Unveiling the Secrets of a Rare r-Process Star in the Ultraviolet
Hansen et al. analyze the metal-poor star J0538, revealing detailed abundances of 43 elements, including rare r-process products like gold and cadmium. Using UV observations from Hubble, they find unexpected star-to-star variation, suggesting non-LTE effects. Their findings support ongoing efforts to trace the cosmic origins of heavy elements and hint at the star’s possible origin in a disrupted dwarf galaxy.
Unearthing Ancient Stars: The Discovery of Two Metal-Poor R-Process Enriched Stars
Astronomers discovered two ancient metal-poor stars enriched in r-process elements, shedding light on the origins of heavy elements. BPS CS 29529-0089, an r-II star, likely formed in the Milky Way’s proto-disk, while TYC 9219-2422-1, an r-I star, originated in the Gaia-Sausage-Enceladus merger. Their chemical signatures suggest enrichment by neutron star mergers and possibly a single Population III supernova, challenging existing theories on galactic evolution.
Exploring the Chemical Fingerprints of Metal-Poor Stars: Insights from the MINCE III Project
The MINCE III project analyzes 99 intermediate-metallicity stars to understand neutron-capture elements, key to the Milky Way’s chemical history. Using high-resolution spectra, the study reveals chemical abundances, including unique findings like a lithium-rich star. Results align with models of Galactic evolution, highlighting the origins of heavy elements through processes like supernovae and neutron-star mergers, advancing our understanding of the Galaxy's formation.
The Riddle of Cosmic Heavyweights: How Stars Forge Elements in the Early Universe
The CERES project investigates how early stars formed heavy elements through neutron-capture processes. Focusing on 52 ancient metal-poor stars, the study found that the rapid r-process dominated at low metallicities, while the slower s-process emerged later. Variations in element abundances suggest diverse nucleosynthesis events, with findings aligning well with galactic chemical evolution models, shedding light on the universe's early chemical enrichment.