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A: Fachverband Atomphysik

A 31: Poster Session III

A 31.23: Poster

Donnerstag, 9. März 2017, 17:00–19:00, P OG1

Optical spectroscopy of highly ionized ruthenium of astrophysical interest — •Hendrik Bekker¹, Paul Marie¹, Chintan Shah¹, Klaus Werner², and José R. Crespo López-Urrutia¹ — ¹Max-Planck-Institut für Kernphysik, Heidelberg — ²Eberhard Karls Universität, Tübingen

Observations of trans-iron elements in certain stars are a window into the slow neutron capture process (s-process) [1]. To interpret the spectra of these objects, atomic data of highly charged trans-iron ions are required. In this work several charge states of ruthenium (Z = 44) were investigated. The Heidelberg electron beam ion trap (HD-EBIT) was employed to charge-state selectively ionize and excite ruthenium ions through electron impact. The spectra of subsequent fluorescence light were recorded using a grating spectrometer. In total, 47 optical lines of the charge states Ru⁹⁺ to Ru¹⁸⁺ were measured. These were compared to predictions from atomic theory, resulting in tentative identifications of transitions and determination of ionization energies. Ruthenium ions are of interest here as their electronic structures are similar to those of technetium ions (Z = 43), the lightest unstable element. Due to the limited lifetime of Tc, its observation in stars gives insight into the stellar evolution and dredge-up processes [2].

[1] K. Werner et al., ApJL, 753, L7 (2012)

[2] P.W. Merrill, The Astrophysical Journal 116 21 (1952)