Ultraviolet Spectral Synthesis of Iota Herculis

Abstract

The atmospheric abundances of elements provide essential insights into the formation and evolution history of stars. The visible wavelength window has been used almost exclusively in the past to determine the abundances of chemical elements in B-type stars. However, some elements do not have useful spectral lines in the visible. A high resolution spectrum of $\iota$~Herculis is available from 999 to 1400\,Å.\ In this project, we investigate the abundance determination in the UV. We identify the elements whose abundances can be tested, and search for elements whose abundances can be determined in the UV to add to those in the current literature. We also investigate the completeness of the VALD line list in this region, and the adequacy of LTE modeling in the UV for this star. We have used the LTE spectrum synthesis code {\sc zeeman} to model the UV spectrum of $\iota$~Herculis for elements with 5 $\le$ Z $\le$ 80. Abundances or upper limits are derived for 24 elements. We find that most of our results are in reasonable agreement with previous results. We estimate a value or an upper limit for the abundance of nine elements in this star that were not detected in the visible. LTE UV spectral synthesis is found to be a useful tool for abundance determination, even though limitations such as incomplete and uncertain atomic data, uncertain continuum normalization and scattered light, and severe blending can introduce difficulties. The high abundance of two heavy elements may be a sign of radiative levitation.

arXiv comment!2 pages plus 2 appendices

References in corpus (9)

• The chemical composition of the Sun
• The elemental composition of the Sun II. The iron group elements Sc to Ni
• The elemental composition of the Sun I. The intermediate mass elements Na to Ca
• The elemental composition of the Sun III. The heavy elements Cu to Th
• Testing common classical LTE and NLTE model atmosphere and line-formation codes for quantitative spectroscopy of early-type stars
• Atmospheric velocity fields in tepid main sequence stars
• Lithium-Beryllium-Boron : Origin and Evolution
• No detection of large-scale magnetic fields at the surfaces of Am and HgMn stars
• A search for weak or complex magnetic fields in the the B3V star iota Herculis

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• Non-LTE line formation for Si I-II-III in A-B stars and the origin of Si II emission lines in iota Her
• Chemical diversity among A-B stars with low rotational velocities: non-LTE abundance analysis
• HR 8844: a new transition object between the Am stars and the HgMn stars ?