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 Tools annual

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 monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

We have entered an era of large spectroscopic surveys in which we canmeasure, through automated pipelines, the atmospheric parameters and chemicalabundances for large numbers of stars. Calibrating these survey pipelines usinga set of "benchmark stars" in order to evaluate the accuracy and precision ofthe provided parameters and abundances is of utmost importance. The recentproposed set of Gaia FGK benchmark stars of Heiter et al. (2015) has norecommended stars within the critical metallicity range of $-2.0 <$ [Fe/H] $<-1.0$ dex. In this paper, we aim to add candidate Gaia benchmark stars insideof this metal-poor gap. We began with a sample of 21 metal-poor stars which wasreduced to 10 stars by requiring accurate photometry and parallaxes, andhigh-resolution archival spectra. The procedure used to determine the stellarparameters was similar to Heiter et al. (2015) and Jofre et al. (2014) forconsistency. The effective temperature (T$_{\mathrm{eff}}$) of all candidatestars was determined using the Infrared Flux Method utilizing multi-bandphotometry. The surface gravity (log g) was determined through fitting stellarevolutionary tracks. The [Fe/H] was determined using four differentspectroscopic methods fixing the T$_{\mathrm{eff}}$ and log g from the valuesdetermined independent of spectroscopy. We discuss, star-by-star, the qualityof each parameter including how it compares to literature, how it compares to aspectroscopic run where all parameters are free, and whether Fe Iionisation-excitation balance is achieved. From the 10 stars, we recommend asample of five new metal-poor benchmark candidate stars which have consistentT$_{\mathrm{eff}}$ , log g, and [Fe/H] determined through several means. Thesestars can be used for calibration and validation purpose of stellar parameterand abundance pipelines and should be of highest priority for futureinterferometric studies.

Gaia FGK Benchmark Stars: New Candidates At Low-Metallicities