Open AccessAn astrophysical oscillator strength for the S ii 94.7‐nm resonance line and S abundances in DLAs
Author(s) -
Bonifacio Piercarlo,
Caffau Elisabetta,
Centurión Miriam,
Molaro Paolo,
Vladilo Giovanni
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04495.x
Subject(s) - physics , spectrograph , astrophysics , observatory , line (geometry) , spectral line , telescope , oscillator strength , astronomy , geometry , mathematics
By using UV spectra for the O star HD 93521 taken with the ORFEUS II echelle spectrograph, we determine an ‘astrophysical’ f value for the S ii λ 94.7‐nm line: f=0.00498 −0.00138 +0.00172 , error at 1 σ level. This is almost a factor of 30 smaller than the guessed value found in the Kurucz data base ( f=0.1472) , which was until now the only one available for this transition. We use our ‘astrophysical’ f to investigate the S abundance in two damped Ly α absorption systems (DLAs) observed with the UV–Visual Echelle Spectrograph (UVES) at the European Southern Observatory's 8.2‐m Kueyen telescope. In the case of the absorber at z abs =3.02486 towards QSO 0347‐3819, we find a sulphur column density which is consistent, within errors, with that determined by Centurión et al. by means of the λ 125.9‐nm line, thus providing an external check on the accuracy of our f value. For the damped absorber at z abs =4.4680 towards BR J0307‐4945, we determine a high value of the S abundance, which, however, is probably the result of blending with Ly α forest lines.