Ionization fractions and mass-loss in O stars [chapter]

Raman K. Prinja, Ian D. Howarth
1987 Circumstellar Matter  
Introduction -The most sensitive indicators of mass-loss for stars in the upper left part of the HR diagram are the UV Ρ Cygni profiles observed in the resonance lines of common ions such as Ν V, Si IV, and C IV. We present here some results from a study of these lines in the high resolution IUE spectra of 197 Ο stars. Profile fits were carried out in the manner described by Prinja & Howarth (1986) for all unsaturated Ρ Cygni resonance doublets. The parameterisations adopted enable the product
more » ... enable the product of mass-loss rate (M) and ion fraction (*?,·) to be determined at a given velocity, such that A4 qi°CNi R^ Voo, where Ni is the column density of
doi:10.1007/978-94-009-3887-8_111 fatcat:yf2sxc2dzvdzhfnazmrlixku6u