EGAS41 - Swansea University

41 st EGAS CP 124 Gdańsk 2009
Lifetime measurements in singly ionized ruthenium.
Oscillator strength and Landé factor calculations in singly
and doubly ionized ruthenium.
P. Palmeri 1 , P. Quinet 1,2 , V. Fivet 6 , É. Biécont1,2 , C. H. Cowley 3 , L. Engström 4 ,
H. Lundberg 6 , S. Hartman 5 , H. Nilsson 5
1 Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium
2 ZPNAS, Université de Liège, B15 Sart Tilman, B-4060 Liège, Belgium
5 Department of Astronomy, University of Michigan, Snn Arbor, MI 48189-1090, USA
4 Department of Physics, Lund University, PO Box 118, SE-221 00 Lund, Sweden
5 Lund Observatory, Lund University, EO Box 46, SE-221 00 Lund, Sweden
∗ Corresponding author: P.Palmeri@umh.ac.be,
Determination of the Ru abundance in the atmospheres of stars of different spectral
classes is important for understanding nucleosynthesis processes in the late stages of stellar
evolution. Robust identifications of this element however are rare in upper main sequence
CP stars. Cowley et al. (2008) suggested that Ru II was present in the unusual star
HD 65969, based on wavelength coincidence statistics. In Przybylski’s star (HD 101065),
some Ru II identifications were also made by Cowley and Bidelman. For more details,
see [1]. Also in the star HR 465, a number of identifications have been attributed to Ru
I and Ru II transitions (see [2]).
A new set of theoretical f-values is reported for 138 Ru II transitions of astrophysical
interest involving energy levels below 58022 cm −1 . The theoretical model, i.e. the
relativistic Hartree-Fock (HFR) approximation including core-polarization effects [3,7],
has been tested by comparing theoretical lifetimes with new measurements performed
by time-resolved laser-induced fluorescence spectroscopy (TR-LIF) [5,6] for 23 4d 6 ( 5 D)5p
odd levels of Ru II and also by comparing theoretical and experimental Landé g-factors.
As an extension of these results, the first set of transition probabilities is proposed for
25 strong lines depopulating the 4d 5 5p 6,7 P ◦ terms of Ru III.
The present results are expected to help the astrophysicists for more quantitative
investigation of the chemical composition of these CP stars based on robust line identifications.
The analysis of some stellar spectra on the basis of the new f-values obtained in
the present work is indeed in progress but the details will be reported elsewhere.
The present results will be published in A & A.
References
[1] http://www.astro.lsa.umich.edu/∼ cowley/uvall.
[2] http://www.astro.lsa.umich.edu/∼ cowley/hr465.html.
[3] R.D. Cowan The Theory of Atomic Structure and Spectra, Berkeley, CA, University of
California Press (1981)
[4] P. Quinet, P. Palmeri, É. Biémont, M.M. McCurdy, G. Rieger, E.H. Pinnington, M.E.
Wickliffe, J.E. Lawler MNRAS 308, 934 (1999)
[5] P. Quinet, P. Palmeri, V. Fivet, É. Biémont, H. Nilsson, L. Engström, H. Lundberg,
Phys. Rev. A 77, 022501 (1-9) (2007)
[6] H. Nilsson, L. Engström, H. Lundberg, P. Palmeri, V. Fivet, P. Quinet, É. Biémont,
Eur. Phys. J. D 549, 13 (2008)
[7] P. Palmeri, P. Quinet, V. Fivet, É. Biémont, H. Nilsson, L. Engström, H. Lundberg,
Phys. Scr. 78, 015304 (1-5) (2008)
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