TY - JOUR

T1 - VUV oscillator strengths for iron lines of astrophysical importance

AU - Hartman, H.

AU - Nilsson, H.

AU - Huldt, S.

AU - Johansson, S.

AU - Sörensen, S.

AU - Johnson, M. S.

AU - Von Hessberg, P.

PY - 2008

Y1 - 2008

N2 - FeII lines are of great importance in analyses of stars and nebulae, not only for abundance studies, but also for diagnostics of the plasma conditions and derivation of physical properties such as temperature, electron density and radiation field. We present a project where the ultimate goal is to derive transition rates for specific Fe II 4s - 5p transitions at VUV wavelengths. These are important for many astrophysical applications, e.g. in objects where line fluorescence is prominent as well as stars observed in the ultraviolet FUSE and HST/STIS region. In this wavelength region many other iron-group element ions have important transitions, which also will be measured. This work is performed as absorption measurements using a FeII hollow-cathode discharge, illuminated by synchrotron radiation at the MAX-lab facility (Lund, Sweden). The intensity ratio between absorption lines from a specific lower level can be determined, and transformed to an absolute scale using previously known f-values for a few lines. We present results from low spectral resolution test runs on MAX-I, and outline the next step with its requirements for a high-resolution setup at MAX-III.

AB - FeII lines are of great importance in analyses of stars and nebulae, not only for abundance studies, but also for diagnostics of the plasma conditions and derivation of physical properties such as temperature, electron density and radiation field. We present a project where the ultimate goal is to derive transition rates for specific Fe II 4s - 5p transitions at VUV wavelengths. These are important for many astrophysical applications, e.g. in objects where line fluorescence is prominent as well as stars observed in the ultraviolet FUSE and HST/STIS region. In this wavelength region many other iron-group element ions have important transitions, which also will be measured. This work is performed as absorption measurements using a FeII hollow-cathode discharge, illuminated by synchrotron radiation at the MAX-lab facility (Lund, Sweden). The intensity ratio between absorption lines from a specific lower level can be determined, and transformed to an absolute scale using previously known f-values for a few lines. We present results from low spectral resolution test runs on MAX-I, and outline the next step with its requirements for a high-resolution setup at MAX-III.

U2 - 10.1088/1742-6596/130/1/012010

DO - 10.1088/1742-6596/130/1/012010

M3 - Journal article

AN - SCOPUS:65649131192

VL - 130

JO - Journal of Physics: Conference Series

JF - Journal of Physics: Conference Series

SN - 1742-6588

M1 - 012010

ER -