A unique infrared spectropolarimetric unit for CRIRES+
Date Issued
2018
Author(s)
Piskunov, Nikolai
•
Stempels, Eric
•
Lavail, Alexis
•
Escuti, Michael
•
Snik, Frans
•
Dolgopolov, Andrey
•
Rozel, Milan
•
Durandet, Candice
•
Hatzes, Artie
•
Bristow, Paul
•
•
Cumani, Claudio
•
Dorn, Reinhold J.
•
Haimerl, Andreas
•
Heiter, Ulrike
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Hinterschuster, Renate
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Follert, Roman
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Ives, Derek
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Jung, Yves
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Kerber, Florian
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Klein, Barbara
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Lizon, Jean-Louis
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Marquart, Thomas
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Molina-Conde, Ignacio
•
Pasquini, Luca
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Paufique, Jérôme
•
•
Reiners, Ansgar
•
Seemann, Ulf
•
Stegmeier, Jörg
•
Tordo, Sebastien
•
Valenti, Elena
Abstract
High-resolution infrared spectropolarimetry has many science applications in astrophysics. One of them is measuring weak magnetic fields using the Zeeman effect. Infrared domain is particularly advantageous as Zeeman splitting of spectral lines is proportional to the square of the wavelength while the intrinsic width of the line cores increases only linearly. Important science cases include detection and monitoring of global magnetic fields on solar-type stars, study of the magnetic field evolution from stellar formation to the final stages of the stellar life with massive stellar winds, and the dynamo mechanism operation across the boundary between fully- and partially-convective stars. CRIRES+ (the CRIRES upgrade project) includes a novel spectropolarimetric unit (SPU) based on polar- ization gratings. The novel design allows to perform beam-splitting very early in the optical path, directly after the tertiary mirror of the telescope (the ESO Very Large Telescope, VLT), minimizing instrumental polariza- tion. The new SPU performs polarization beam-splitting in the near-infrared while keeping the telescope beam mostly unchanged in the optical domain, making it compatible with the adaptive optics system of the CRIRES+ instrument. The SPU consists of four beam-splitters optimized for measuring circular and linear polarization of spectral lines in YJ and HK bands. The SPU can perform beam switching allowing to correct for throughput in each beam and for variations in detector pixel sensitivity. Other new features of CRIRES+, such as substantially increased wavelength coverage, stability and advanced data reduction pipeline will further enhance the sensitivity of the polarimetric mode. The combination of the SPU, CRIRES+ and the VLT is a unique facility for making major progress in understanding stellar activity. In this article we present the design of the SPU, laboratory measurements of individual components and of the whole unit as well as the performance prediction for the operation at the VLT.
Coverage
Ground-based and Airborne Instrumentation for Astronomy VII
All editors
Evans, Christopher J.; Simard, Luc; Takami, Hideki
Series
Volume
10702
Start page
1070234
Conferenece
Ground-based and Airborne Instrumentation for Astronomy VII
Conferenece place
Austin, Texas, United States
Conferenece date
10-15 June, 2018
Issn Identifier
0277-786X
Ads BibCode
2018SPIE10702E..34P
Rights
open.access
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