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

High-resolution near-ultraviolet spectra of the yellow hypergiants HR 8752and rho Cassiopeiae indicate high effective temperatures placing both starsnear the T_eff border of the ``yellow evolutionary void''. At present, thetemperature of HR 8752 is higher than ever. For this star we foundTeff=7900+-200 K, whereas rho Cassiopeiae has Teff=7300+-200 K. Both, HR 8752and rho Cassiopeiae have developed strong stellar winds with Vinf ~ 120 km/sand Vinf ~ 100 km/s, respectively. For HR 8752 we estimate an upper limit forthe spherically symmetric mass-loss of 6.7X10^{-6}M_solar/yr. Over the pastdecades two yellow hypergiants appear to have approached an evolutionary phase,which has never been observed before. We present the first spectroscopicevidence of the blueward motion of a cool super/hypergiant on the HR diagram.Comment: 13 pages including 3 figures. Accepted for publication in ApJ Letter

The Yellow Hypergiants HR 8752 and ρ Cassiopeiae near the Evolutionary Border of Instability