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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We examine the spatial distribution of the oldest and most metal poor stellarpopulations of Milky Way-sized galaxies using the APOSTLE cosmologicalhydrodynamical simulations of the Local Group. In agreement with earlier work,we find strong radial gradients in the fraction of the oldest (tform < 0.8 Gyr)and most metal poor ([Fe/H]< -2.5) stars, both of which increase outwards. Themost metal poor stars form over an extended period of time; half of them formafter z = 5.3, and the last 10% after z = 2.8. The age of the metal poorstellar population also shows significant variation with environment; a highfraction of them are old in the galaxy's central regions and an even higherfraction in some individual dwarf galaxies, with substantial scatter from dwarfto dwarf. Overall, over half of the stars that belong to both the oldest andmost metal-poor population are found outside the solar circle. Somewhatcounter-intuitively, we find that dwarf galaxies with a large fraction of metalpoor stars that are very old are systems where metal poor stars are relativelyrare, but where a substantial old population is present. Our results provideguidance for interpreting the results of surveys designed to hunt for theearliest and most pristine stellar component of our Milky Way.

The oldest and most metal poor stars in the APOSTLE Local Group simulations