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

A history is given of the discovery between 1914 and 1935 of stars ofintermediate luminosity between giants and dwarfs with spectral types betweenG0 to K3. The Mt Wilson spectroscopists identified about 90 such stars in their1935 summary paper of spectroscopic absolute magnitudes for 4179 stars. Called"subgiants" by Str\"omberg, these 90 stars defined the group at the time. Theposition of the Mt Wilson subgiants in the HR diagram caused difficulties incomparisons of high weight trigonometric parallaxes being measured and withRussell's prevailing evolution proposal, and critics questioned the reality ofthe Mt Wilson subgiants. We compare, star-by-star, the Mt Wilson spectroscopicabsolute magnitudes of the 90 stars defining their sample against thoseabsolute magnitudes derived from Hipparcos (HIP) trigonometric parallaxes. Weaddress concerns over biases in the Mt Wilson calibration sample and biasescreated by the adopted methodology for calibration. Historically, theseconcerns were sufficient to discredit the discovery of subgiants in the MtWilson sample. However, as shown here, the majority of the Mount Wilson starsidentified as subgiants that also have reliable HIP trigonometric parallaxes dolie among the subgiant sequence in the HIP HR diagram. Moreover, no significantoffset is seen between the M(V) brightnesses derived from the Mt Wilsonspectroscopic parallaxes and the M(V) values derived from Hipparcostrigonometric parallaxes with a fractional error of 10%, which confirms in animpressive manner the efficacy of the original Mt Wilson assessments. Theexistence of subgiants proved that Russell's contraction proposal for stellarevolution from giants to the main sequence was incorrect. Instead, Gamow's 1944unpublished conjecture that subgiants are post main-sequence stars just havingleft the main sequence was very nearly correct but was a decade before itstime.

Comparison of Hipparcos Trigonometric and Mount Wilson Spectroscopic Parallaxes for 90 Subgiants that Defined the Class in 1935