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

Thanks to the recent very high-precision photometry of red giants fromsatellites such as Kepler, precise mass and radius values as well as accurateinformation of evolutionary stages are already established by asteroseismicapproach for a large number of G-K giants. Based on the high-dispersion spectraof selected such 55 red giants in the Kepler field with precisely known seismicparameters (among which parallaxes are available for 9 stars), we checked theaccuracy of the determination method of stellar parameters previously appliedto many red giants by Takeda et al. (2008, PASJ, 60, 781), since it may bepossible to discriminate their complex evolutionary status by using the surfacegravity vs. mass diagram. We confirmed that our spectroscopic gravity and theseismic gravity satisfactorily agree with each other (to within ~0.1 dex)without any systematic difference. However, the mass values of He-burning redclump giants derived from stellar evolutionary tracks (~2-3 Msun) were found tobe markedly larger by ~50% compared to the seismic values (~1-2 Msun) thoughsuch discrepancy is not seen for normal giants in the H-burning phase, whichreflects the difficulty of mass determination from intricately overlappingtracks on the luminosity vs. effective temperature diagram. This consequenceimplies that the mass results of many red giants in the clump region determinedby Takeda et al. (2008) are likely to be significantly overestimated. We alsocompare our spectroscopically established parameters with recent literaturevalues, and further discuss the prospect of distinguishing the evolutionarystatus of red giants based on the conventional (i.e., non-seismic) approach.

Spectroscopic study of red giants in the Kepler field with asteroseismologically established evolutionary status and stellar parameters