Spectra of high-Zions of stellar interest. a theoretical study of (d+s)8mixed configurations in 5d- and 4d- elements

Some 5 d -elements are present in chemical peculiar stars of Hg-Mn type and the interpretation of their spectra II and III needs revisions and extensions. The existing data are used for predictions in the OsI isoelectronic sequence, within the framework of the Slater-Racah parametric method and with the support of "generalized least squares" fits for the energy parameters. Far configurations effects are described by effective parameters of electrostatic and magnetic types and the mixing of 5 d 8 , 5 d 7 6 s and 5 d 6 6 s 2 is calculated explicitly. The results on the sequence Ir II-Bi VIII are compared with those obtained on the similar sequence of the 4 d -elements from Rh II to Sb VIII.