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Extensions of the Wilson-Bappu Effect Among Very Luminous Stars

Published online by Cambridge University Press:  14 August 2015

Robert E. Stencel*
Affiliation:
NASA/Johnson Space Center, Houston Texas

Extract

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Twenty years ago, Wilson and Bappu (1957) published their observational correlation of MV and the logarithm of the full width at half maximum of the CaII K-line central emission for G, K and M stars. The technique was stated to have ± 0m.5 accuracy, while a tabulation of MV(K) by Wilson (1976) suggests the error may only be ± 0m.3. This accuracy makes the approach valuable for late-type supergiants since other methods suffer from comparable errors. However, for F through M supergiants (Ia, 0), circumstellar absorption obscures the chromospheric K-line core emission and excludes such objects from the Wilson-Bappu correlation. I report here on a new class of emission lines in late-type giant and supergiant spectra that exhibit MV correlated widths, yet are detectable among the brightest stars.

Type
Part I: Fundamentals of the HR Diagram
Copyright
Copyright © Reidel 1978 

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