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

F. BOUCHY; R. F. DÍAZ; G. HÉBRARD; L. ARNOLD; I. BOISSE; X. DELFOSSE; S. PERRUCHOT

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2013 vol. 549 p. 1 - 11

0004-6361

High-precision spectrographs play a key role in exoplanet searches and Doppler asteroseismology using the radial velocity technique. The 1  m s-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  m s-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  m s-1. It is now fully efficient for the detection of low-mass exoplanets down to 5?10 Mearth and for the identification of acoustic modes down to a few tens of  cm s-1.