INVESTIGADORES
DIAZ Rodrigo Fernando
congresos y reuniones científicas
Título:
Higher-precision radial velocity measurements with the SOPHIE spectrograph using octagonal-section fibers
Autor/es:
S. PERRUCHOT; F. BOUCHY; B. CHAZELAS; R. F. DÍAZ; G. HÉBRARD; K. ARNAUD; L. ARNOLD; G. AVILA; X. DELFOSSE; I. BOISSE; G. MOREAUX; F. PEPE; Y. RICHAUD; A. SANTERNE; R. SOTTILE; D. TEZIER
Lugar:
San Diego
Reunión:
Congreso; Techniques and Instrumentation for Detection of Exoplanets V; 2011
Resumen:
High-precision spectrographs play a key role in exoplanet searches using
the radial velocity technique. But at the accuracy level of 1 m.s-1,
required for super-Earth characterization, stability of fiber-fed
spectrograph performance is crucial considering variable observing
conditions such as seeing, guiding and centering errors and, telescope
vignetting. In fiber-fed spectrographs such as HARPS or SOPHIE, the
fiber link scrambling properties are one of the main issues. Both the
stability of the fiber near-field uniformity at the spectrograph
entrance and of the far-field illumination on the echelle grating
(pupil) are critical for high-precision radial velocity measurements due
to the spectrograph geometrical field and aperture aberrations. We
conducted tests on the SOPHIE spectrograph at the 1.93-m OHP telescope
to measure the instrument sensitivity to the fiber link light feeding
conditions: star decentering, telescope vignetting by the dome,and
defocussing. To significantly improve on current precision, we designed
a fiber link modification considering the spectrograph operational
constraints. We have developed a new link which includes a piece of
octagonal-section fiber, having good scrambling properties, lying inside
the former circular-section fiber, and we tested the concept on a bench
to characterize near-field and far-field scrambling properties. This
modification has been implemented in spring 2011 on the SOPHIE
spectrograph fibers and tested for the first time directly on the sky to
demonstrate the gain compared to the previous fiber link. Scientific
validation for exoplanet search and characterization has been conducted
by observing standard stars.