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14 February 2003 Spectropolarimetry with CRIRES: technical aspects and scientific potential
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ESO is presently building an adaptive-optics fed Cryogenic Infrared Echelle Spectrograph (CRIRES) for the VLT-observatory operating in the wavelength range from 1-5μm. Spectro-polarimetry with a focus on circular polarization in the infrared is particularly interesting as the ratio of Zeeman-splitting to intrinsic line widths improves linearly with wavelength. Also the contrast between absorption lines in starspots and the surrounding photosphere becomes more favourable when observing a longer wavelengths (i.e. closer to the Jeans-case). Moreover it is well known that even extremely red objects such as Brown Dwarf candidates show X-ray emission and hence must have magnetic activity. CRIRES shall be equipped with a reflective phase retarder and a Wollaston-prism allowing nearly un-compromised measurements of circular polarization at a spectral resolution of 100000. Linear polarization measurements are also possible, but most likely with compromised performance. We show preview spectra of Zeeman sensitive transitions in the infrared based on Fourier-transform spectra of sunspots from literature.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hans-Ulrich Kaeufl, Alan F. M. Moorwood, and Jean-Francois Pirard "Spectropolarimetry with CRIRES: technical aspects and scientific potential", Proc. SPIE 4843, Polarimetry in Astronomy, (14 February 2003);

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