Spectrum variability of the silicon AP star HD 192913

Abstract

The metal lines in the spectrum of the silicon Ap star HD 192913 are found to change with the photometric period. Many commonly found atomic species have lines which vary together in phase. The spectrum contains lines of most of the doubly ionized rare earth elements.

Ab initio calculations of oscillator strengths and Landé factors for NdIII

“…Nd iii has been observed in the spectrum of several CP stars having strong lines of Nd ii, for example HR 465, HD 51418, and HD 200311 (Cowley 1976;Aikman et al 1979); Nd ii and Nd iii have also been found in the Si star HD 192913 (Cowley & Crosswhite 1978;Ryabchikova et al 1990). We have previously reported on Nd iii in HR 6870 and γ Equ , and recent studies by our group have also revealed the strong presence of both Nd ii and Nd iii in the spectrum of HD 101065 (Cowley et al 2000), a rapidly oscillating Ap (roAp) star and arguably one of the most chemically bizarre objects in the Galaxy.…”

uvby FCAPT photometry of the mCP stars HR 2258, MW Vul, and HR 9017 and the HgMn star 46 ρ Aqr

“…It has a definite λ5200 broad, continuum feature (Adelman 1982;Adelman & Pyper 1993). Ryabchikova et al (1990) studied its spectrum variability. Babcock (1958) reported a magnetic field of 483 ± 221 G. Adelman & Knox (1994) determined a period of 16.840 days from their set of 87 FCAPT Strömgren photometry combined with the V values of Winzer.…”

Measurement of lifetimes by laser-induced fluorescence and determination of transition probabilities of astrophysical interest in Nd III

“…As pointed out in the introduction, Nd III has been identified or mentioned as possibly present in a number of stars : HR 465, HD 51418, HD 200311 (Cowley 1976;Aikman et al 1979;Bidelman et al 1995), HD 192913 (Cowley & Crosswhite 1978Ryabchikova et al 1990), HD 101065 ) but the identification can be complicated by problems of different types. The identification of lanthanides in stars showing strong Si II lines is made difficult by the fact that only a few stars are known which show very sharp lines.…”

“…Doubly ionized neodymium (Nd III), which is expected to be the dominant species in hotter stars, has been identified in the spectra of some CP stars like HR 465, HD 51418 and HD 200311 (Cowley 1976;Aikman et al 1979;Bidelman et al 1995) and in the spectrum of HD 192913 and HD 43819, Bp stars of the Si subgroup (Cowley & Crosswhite 1978;Ryabchikova et al 1990). …”