Paper
30 June 2006 A study of the UVES instrumental polarization
S. Hubrig, N. Nesvacil, G. Mathys, C. Ledoux
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Abstract
Previous studies of strongly magnetic stars with spectral lines resolved into their magnetically split components showed for some stars systematic differences in the mean field modulus values determined from high resolution spectra obtained with different spectrographs at different observatories. It is suspected that they result from modification of the linear polarisation of the spectral lines of the star by the optical train. Since this polarisation varies from star to star, the resulting effect also differs from one star to the next. As high resolution spectra obtained with the Ultraviolet and Visible Echelle Spectrograph (UVES) at the ESO VLT are nowadays used for the measurement of stellar surface magnetic fields, we recently conducted a study of the UVES instrumental polarisation. For this purpose, we carried out a large number of measurements of magnetically split Zeeman components in the spectra of magnetic stars taken with various instrumental settings using different dichroics, the highest resolution image slicer and the depolarizer. Our measurements show no evidence for the presence of a UVES instrumental polarisation.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. Hubrig, N. Nesvacil, G. Mathys, and C. Ledoux "A study of the UVES instrumental polarization", Proc. SPIE 6269, Ground-based and Airborne Instrumentation for Astronomy, 62692R (30 June 2006); https://doi.org/10.1117/12.670711
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KEYWORDS
Stars

Magnetism

Iron

Polarization

Chromium

Spectrographs

Spectral resolution

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