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 open cluster NGC 6791 is among the oldest, most massive and metal-richopen clusters in the Galaxy. High-resolution $H$-band spectra from the ApachePoint Observatory Galactic Evolution Experiment (APOGEE) of 11 red giants inNGC 6791 are analyzed for their chemical abundances of iron, oxygen, andsodium. The abundances of these three elements are found to be homogeneous(with abundance dispersions at the level of $\sim$ 0.05 - 0.07 dex) in thesecluster red giants, which span much of the red-giant branch (T$_{\rm eff}$$\sim$ 3500K - 4600K), and include two red-clump giants. From the infraredspectra, this cluster is confirmed to be among the most metal-rich clusters inthe Galaxy ($<$[Fe/H]$>$ = 0.34 $\pm$ 0.06), and is found to have a roughlysolar value of [O/Fe] and slightly enhanced [Na/Fe]. Non-LTE calculations forthe studied Na I lines in the APOGEE spectral region ($\lambda$16373.86\AA\ and$\lambda$16388.85\AA) indicate only small departures from LTE ($\leq$ 0.04 dex)for the parameter range and metallicity of the studied stars. The previouslyreported double population of cluster members with different Na abundances isnot found among the studied sample.

Sodium and Oxygen Abundances in the Open Cluster NGC 6791 from APOGEE H-Band Spectroscopy