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.
Unraveling the Mystery of the Faintest Galaxies: A Deep Dive into Sagittarius II and Aquarius II
Astronomers used the Gemini/GHOST spectrograph to study Sagittarius II (Sgr2) and Aquarius II (Aqu2), two faint Milky Way satellites. Their analysis suggests Aqu2 is a dark matter-dominated ultra-faint dwarf galaxy, while Sgr2 remains ambiguous, possibly a star cluster. Chemical signatures and star movements were key to these classifications. The study highlights the difficulty in distinguishing faint galaxies from clusters and the need for further observations and simulations.
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.
Decoding the Chemical Puzzle of the Sagittarius Dwarf Galaxy
Researchers analyzed 37 stars in the Sagittarius Dwarf Galaxy to study its chemical evolution. They found significant enrichment of heavy elements through the r-process, likely from neutron star mergers. Stars in the galaxy's core and tidal streams showed similar chemical patterns, indicating a shared history. The study highlights how dwarf galaxies contribute to the universe's chemical complexity.
Tracing the Galactic Past: Linking Stars to Reticulum II’s Tidal History
Researchers traced the origins of r-process-enhanced stars in the Milky Way halo to the ultra-faint dwarf galaxy Reticulum II (Ret-II). Using advanced simulations and star catalogs, they identified 93 stars likely ejected from Ret-II over 11.5 billion years as it orbited the galaxy. This study highlights Ret-II’s role in the Milky Way’s formation and provides insights into the origins of heavy elements through cosmic events like neutron star mergers.