The Complex Structure of the Ca II H and K Lines in the Spectrum of the A0ep Star with Infrared Excess HD 190073

Abstract

Radial velocities and profiles of the components of the H and K lines in the spectrum of HD 190073 are analyzed in a 24-spectrum sample covering the period 1943–74. A 2-to-1 ratio in the radial velocities of some components is shown not to be significant on a spectrum-to-spectrum basis, contrary to suggestions by Merrill (1951) and Scargle (1973). The details of the H and K complex structure are correlated with the profiles of the Balmer lines. Radiative forces acting selectively via a resonance scattering mechanism of Ca⁺ atoms are capable of producing the main features of the complex profiles of H and K in HD 190073 and in other stars exhibiting similarities to HD 190073 (such as P Cygni Balmer lines and infrared excess).