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SOPHIE+: First results of an octagonal-section fiber for high-precision radial velocity measurements

F. Bouchy, R. F. DÝaz, G. HÚbrard, L. Arnold, I. Boisse, X. Delfosse, S. Perruchot, A. Santerne

Abstract
High-precision spectrographs play a key role in exoplanet searches and Doppler asteroseismology using the radial velocity technique. The 1 ms-1 level of precision requires very high stability and uniformity of the illumination of the spectrograph. In fiber-fed spectrographs such as SOPHIE, the fiber-link scrambling properties are one of the main conditions for high precision. To significantly improve the radial velocity precision of the SOPHIE spectrograph, which was limited to 5–6 ms-1, we implemented a piece of octagonal-section fiber in the fiber link. We present here the scientific validation of the upgrade of this instrument, demonstrating a real improvement. The upgraded instrument, renamed SOPHIE+, reaches radial velocity precision in the range of 1–2 ms-1. It is now fully efficient for the detection of low-mass exoplanets down to 5–10 M and for the identification of acoustic modes down to a few tens of cm s-1.

Keywords
instrumentation: spectrographs – techniques: radial velocities – planetary systems – stars: oscillations

Astronomy and Astrophysics
Volume 549, Number of pages A49_1
2013 January

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Instituto de Astrof├şsica e Ci├¬ncias do Espa├žo Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Funda├ž├úo para a Ci├¬ncia e a Tecnologia
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