Chromospheric scaling laws, width-luminosity correlations, and the Wilson-Bappu effect

Journal Article · Thu Mar 01 04:00:00 EST 1979 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156873· OSTI ID:6286267

Ayres, T R

Simple scaling laws are developed to explain the thickness and mean electron density of late-type stellar chromospheres in an effort to understand why the emission cores of effectively thick resonance lines such as Ca II H and K broaden with increasing stellar luminosity (the Wilson-Bappu effect). It is shown that stellar chromospheres become thicker in mass column density as stellar gravity g decreases and that the mean chromospheric electric density n/sub e/ decreases if the chromospheric heating dF/dm is constant with height and if the total heating F/sup tot/ is independent of g. It is also shown that chromospheres becomes thicker and the mean electron density becomes larger than the total chromospheric heating increases. The predicted behavior of the K/sub 1/ minimum separation and full width at half-maximum of the Ca II emission core (W/sub 0/) based on the derived scaling laws agree quantitatively with the observed correlations of these widths with fundamental stellar parameters, particularly surface gravity. In addition, the predicted behavior of the K/sub 2/ peak separation and base emission width with increasing chromospheric heating is consistent with the behavior of the Ca II emission core shapes in solar plages. The analytical arguments suggest that the Wilson-Bappu effect is largely a consequence of hydrostatic equilibrium rather than chromospheric dynamics.

• Research Organization: Joint Institute for Laboratory Astrophysics, University of Colorado
• OSTI ID: 6286267
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 228:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
COOLING
ELECTRON DENSITY
EMISSION SPECTRA
FUNCTIONS
HYDROSTATICS
LINE BROADENING
LINE WIDTHS
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PLAGES
PLASMA
RECOMBINATION
SOLAR ACTIVITY
SPECTRA
SPECTRAL FUNCTIONS
STELLAR ATMOSPHERES