Long Term Variability of the Coronal and Post-Coronal Regions of the Oe Star HD 149757 (zeta Oph)

摘要

In the spectra of Oe and Be stars, many spectral lines present peculiar and complex profiles due to the fact that the observed absorption features are composed of two or more absorption components (Discrete or Satellite Absorption Components—DACs/SACs). Here we detected the presence the SACs phenomenon in the C IV, N IV and N V spectral lines in 11 spectra of the Oe star HD 149757 (zeta Oph), taken with IUE during a period of 13 years.