English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The ultra-faint dwarf galaxy Reticulum II was enriched by a rare and prolificr-process event, such as a neutron star merger. To investigate the nature ofthis event, we present high-resolution Magellan/MIKE spectroscopy of thebrightest star in this galaxy. The high signal-to-noise allows us to determinethe abundances of 41 elements, including the radioactive actinide element Thand first ever detections of third r-process peak elements (Os and Ir) in astar outside the Milky Way. The observed neutron-capture element abundancesclosely match the solar r-process component, except for the first r-processpeak which is significantly lower than solar but matches other r-processenhanced stars. The ratio of first peak to heavier r-process elements impliesthe r-process site produces roughly equal masses of high and low electronfraction ejecta, within a factor of 2. We compare the detailed abundancepattern to predictions from nucleosynthesis calculations of neutron starmergers and magneto-rotationally driven jet supernovae, finding that nuclearphysics uncertainties dominate over astrophysical uncertainties. We measure$\log\mbox{Th/Eu} = -0.84 \pm 0.06\,\text{(stat)} \pm 0.22\,\text{(sys)}$,somewhat lower than all previous Th/Eu observations. The youngest age we derivefrom this ratio is $21.7 \pm 2.8\,\text{(stat)} \pm 10.3\,\text{(sys)}$ Gyr,indicating that current initial production ratios do not well describe ther-process event in Reticulum II. The abundance of light elements up to Zn areconsistent with extremely metal-poor Milky Way halo stars. They may eventuallyprovide a way to distinguish between neutron star mergers andmagneto-rotationally driven jet supernovae, but this would require moredetailed knowledge of the chemical evolution of Reticulum II.

From actinides to zinc: Using the full abundance pattern of the brightest star in Reticulum II to distinguish between different r-process sites