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 report on the elemental abundances of the carbon-enhanced metal-poor(CEMP) star J2217+2104 discovered by our metal-poor star survey with LAMOST andSubaru. This object is a red giant having extremely low Fe abundance([Fe/H]=-4.0) and very large enhancement of C, N, and O with excesses of Na,Mg, Al, and Si. This star is a new example of a small group of such CEMP starsidentified by previous studies. We find a very similar abundance pattern forO-Zn in this class of objects that shows enhancement of elements up to Si andnormal abundance of Ca and Fe-group elements. Whereas the C/N ratio isdifferent among these stars, the (C+N)/O ratio is similar. This suggests that Cwas also yielded with similar abundance ratios relative to O-Zn in progenitors,and was later affected by the CN-cycle. By contrast, the heavy neutron-captureelements Sr and Ba are deficient in J2217+2104, compared to the four objects inthis class previously studied. This indicates that the neutron-capture processin the early Galaxy, presumably the r-process, has no direct connection to thephenomenon that has formed such CEMP stars. Comparisons of the abundancepattern well determined for such CEMP stars with those of supernovanucleosynthesis models constrain the progenitor mass to be about 25Msun, whichis not particularly different from typical mass of progenitors expected forextremely metal-poor stars in general.

LAMOST J2217+2104: a new member of carbon-enhanced extremely metal-poor stars with excesses of Mg and Si