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Centro de Astrofísica da Universidade do Porto

Radial Velocities with CRIRES
Pushing precision down to 5-10 m/s

P. Figueira, F. Pepe, C. Melo, N. C. Santos, C. Lovis, M. Mayor, D. Queloz, A. Smette, S. Udry

With the advent of high-resolution infrared spectrographs, Radial Velocity (RV) searches enter into a new domain. As of today, the most important technical question to address is which wavelength reference is the most suitable for high-precision RV measurements. In this work we explore the usage of atmospheric absorption features. We make use of CRIRES data on two programs and three different targets. We re-analyze the data of the TW Hya campaign, reaching a dispersion of about 6m/s on the RV standard in a time scale of roughly 1 week. We confirm the presence of a low-amplitude RV signal on TW Hya itself, roughly 3 times smaller than the one reported at visible wavelengths.We present RV measurements of Gl 86 as well, showing that our approach is capable of detecting the signal induced by a planet and correctly quantifying it. Our data show that CRIRES is capable of reaching a RV precision of less than 10m/s in a time-scale of one week. The limitations of this particular approach are discussed, and the limiting factors on RV precision in the IR in a general way. The implications of this work on the design of future dedicated IR spectrographs are addressed as well.

Planetary systems, Infrared: stars, Instrumentation: spectrographs, Methods: observational, Techniques: radial velocities

Based on observations taken at the VLT (Paranal), under programs 280.C-5064(A) and 60.A-9051(A), and with the CORALIE spectrograph at the Euler Swiss telescope (La Silla).
Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to ( or via

Astronomy and Astrophysics
Volume 511, Page A55_1
February 2010

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