The first detection of arsenic in any star, including the sun, was made with the high-resolution Echelle spectrometer aboard the Hubble Space Telescope ([Leckrone et al. 1991]). The 1937.6 Å line of As I was detected for the first time in the ultraviolet spectrum of the bright, ultra-sharp-lined B-peculiar star, chi Lupi. This line results from the transition 4p3(4S ) 4p2(3P)5s(4P3/2), which is discussed in Sect. 3 of the present work. Arsenic is known to be present in meteorites ([Anders & Grevesse 1989]). A knowledge of the oscillator strengths of As I is also important for an understanding of the mechanisms involved in arsenic lasers ([Fowles et al. 1974]).
The first detection of As II in the interstellar medium was
made by the Goddard High Resolution Spectrograph aboard the Hubble
Space Telescope ([Cardelli et al. 1993]). Oscillator strengths for various
ultraviolet transitions in As II are discussed in Sect. 4 of
this work. In Sect. 5 we present results for As III.
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