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Session 81 - Variable Cool and Late Type Stars.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[81.05] The Physical Basis of MK Luminosity Classification in the A and F-type Stars

R. O. Gray, P. W. Graham, S. R. Hoyt (Appalachian State U.)

As part of a continuing project investigating the physical basis of luminosity classification in the late A, F and G-type stars, we report on the determination of the basic parameters (effective temperature, gravity, microturbulent velocity and metallicity), using classification-resolution spectra and spectral synthesis, of a number of A and F-type stars, ranging in luminosity class from dwarf (V) to supergiant (Ib). We confirm the suggestion made in earlier papers that microturbulence plays as large a role in the behavior of the MK luminosity criteria (based on lines of ionized species) as gravity, and discuss the existence of a correlation between gravity and the microturbulent velocity. The relevance of this study to the interpretation of MK spectral types is discussed as well.


The author(s) of this abstract have provided an email address for comments about the abstract: grayro@appstate.edu

Program listing for Wednesday