Discovery of TYC 170-1218-1: An Extremely Metal-Poor Star Rich in Heavy Elements and Thorium
Astronomers have identified TYC 170-1218-1, an extremely metal-poor (EMP) star with an iron abundance of [Fe/H] = -3.52 that is highly enriched in r-process elements including europium and thorium. The star, analyzed using high-resolution spectra from two major telescopes, belongs to the rare 'r-II' class and is kinematically linked to the ancient Sequoia accretion event in the Milky Way's history. Its exceptional chemical composition offers a rare window into the nucleosynthesis conditions of the early universe and the first generations of stars.
TYC 170-1218-1 was serendipitously discovered during a search for apparently young, metal-poor stars and subsequently identified as an extremely metal-poor r-II star. Using high-resolution spectra from the UVES instrument at the Very Large Telescope and the MIKE spectrograph at the Magellan Clay Telescope, researchers derived abundances for 33 chemical elements via the MyGIsFOS code and ATLAS 9 model atmospheres. The star exhibits [Fe/H] = -3.52, placing it among the most iron-poor stars known, while its [Eu/Fe] = +1.84 and [Th/Fe] = +1.85 confirm extreme enrichment in r-process heavy elements — those forged primarily in neutron star mergers or certain supernova types. Like most EMP stars, it shows enhancement in alpha elements and is notably carbon-poor relative to iron. Kinematic analysis places the star currently in the Galactic halo, but its orbital history suggests it was accreted into the Milky Way as part of the Sequoia merger event, an ancient galaxy collision. Uranium could not be detected due to insufficient spectral quality, limiting a potential cosmochronometric age estimate. The star's chemical pattern reflects enrichment from only one or a few first-generation supernovae, making it a valuable probe of early cosmic chemical evolution.
What's missing
The study could not detect uranium, which would have enabled a radioactive decay-based age estimate (nucleo-cosmochronometry) for the star. Additionally, the specific astrophysical site(s) responsible for the r-process enrichment — neutron star mergers versus rare core-collapse supernovae — cannot be definitively distinguished from the data presented.
What different sources said
- arXiv astro-phCenter
TYC 170-1218-1: A new r-process-enhanced extremely metal-poor star, rich in Th
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.