https://www.academia.edu/70985020/Ceti_a_probable_Apstar_descendant_entering_the_Hertzsprung_gap
Feb 9, 2022 - Context. 14 Ceti is a subgiant star of F spectral class that displays variations in the S-index of its Ca iiH & K lines and an X-ray emission that is stronger...
hertzsprung gappdfcetiprobableapstar
https://www.aanda.org/articles/aa/abs/2004/02/aa0045/aa0045.html
Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
x rayhertzsprung gapgiant starspectroscopy