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

–  We review current observational and theoretical constraints on the galactic chemical evolution (GCE) of oxygen isotopes to explore whether GCE plays a role in explaining the lower  17 O/ 18 O ratio of the Sun, relative to the present‐day interstellar medium, or the existence of distinct  16 O‐rich and  16 O‐poor reservoirs in the solar system. Although the production of both  17 O and  18 O are related to the metallicity of progenitor stars,  17 O is most likely produced in stars that evolve on longer timescales than those that produce  18 O. Therefore, the  17 O/ 18 O ratio need not have remained constant over time, contrary to preconceptions and the simplest models of GCE. An apparent linear, slope‐one correlation between δ 17 O and δ 18 O in the ISM need not necessarily reflect an O isotopic gradient, and any slope‐one galactocentric gradient need not correspond to  evolution in time . Instead, increasing  17 O/ 18 O is consistent both with observational data from molecular clouds and with modeling of the compositions of presolar grains. Models in which the rate of star formation has decelerated over the past few Gyr or in which an enhanced period of star formation occurred shortly before solar birth (“starburst”) can explain the solar‐ISM O‐isotopic difference without requiring a local input of supernova ejecta into the protosolar cloud. “Cosmic chemical memory” models in which interstellar dust is on average older than interstellar gas predict that primordial solar system solids should be  16 O‐rich, relative to the Sun, in conflict with observations. However, scenarios can be constructed in which the  16 O‐rich contribution of very massive stars could lead to  16 O‐poor solids and a  16 O‐rich bulk Sun, if the solar system formed shortly after a starburst, independent of the popular scenario of photochemical self‐shielding of CO.

Galactic chemical evolution and the oxygen isotopic composition of the solar system