1989/02/01 by R. O. Gray, R. F. Garrison · 5 citations
Physics and Astronomy · Engineering · #Stellar, planetary, and galactic studies #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #Physics #Photometry (optics) #Stars #Astrophysics #Hertzsprung–Russell diagram #Stellar classification #Metallicity #Stellar rotation #Astronomy #Stellar evolution
paper · doi:10.1086/191315
openalex publication_date 1989/02/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/14
The classification for early F-type stars in the MK spectral classification system presented by Gray and Garrison (1987) is refined. The effect of rotation on spectral classification and ubvy-beta photometry of early F-type stars is examined. It is found that the classical luminosity criterion, the 4417 A/4481 A ratio gives inconsistent results. It is shown that most of the stars in the Delta Delphini class of metallic-line stars are either normal or are indistinguishable from proto-Am stars. It is suggested that the designation Delta Delphini should be dropped. The classifications are compared with Stromgren photometry. The effects of rotation on the delta-c<SUB>1</SUB> index in the early-F field dwarfs is demonstrated.