A spectrograph for exoplanet observations calibrated at the centimetre-per-second level

Wilken, Tobias; Curto, Gaspare Lo; Probst, Rafael A.; Steinmetz, Tilo; Manescau, Antonio; Pasquini, Luca; González-Hernández, J. I.; Rebolo, R.; Hänsch, Theodor W.; Udem, Thomas; Holzwarth, Ronald
Bibliographical reference

Nature, Volume 485, Issue 7400, pp. 611-614 (2012).

Advertised on:
5
2012
Journal
Number of authors
11
IAC number of authors
2
Citations
172
Refereed citations
139
Description
The best spectrographs are limited in stability by their calibration light source. Laser frequency combs are the ideal calibrators for astronomical spectrographs. They emit a spectrum of lines that are equally spaced in frequency and that are as accurate and stable as the atomic clock relative to which the comb is stabilized. Absolute calibration provides the radial velocity of an astronomical object relative to the observer (on Earth). For the detection of Earth-mass exoplanets in Earth-like orbits around solar-type stars, or of cosmic acceleration, the observable is a tiny velocity change of less than 10cms-1, where the repeatability of the calibration--the variation in stability across observations--is important. Hitherto, only laboratory systems or spectrograph calibrations of limited performance have been demonstrated. Here we report the calibration of an astronomical spectrograph with a short-term Doppler shift repeatability of 2.5cms-1, and use it to monitor the star HD75289 and recompute the orbit of its planet. This repeatability should make it possible to detect Earth-like planets in the habitable zone of star or even to measure the cosmic acceleration directly.
Related projects
Discovery of a system of super-Earths orbiting the star HD 176986 with about 5.7 and 9.2 Earth masses.
Very Low Mass Stars, Brown Dwarfs and Planets
Our goal is to study the processes that lead to the formation of low mass stars, brown dwarfs and planets and to characterize the physical properties of these objects in various evolutionary stages. Low mass stars and brown dwarfs are likely the most numerous type of objects in our Galaxy but due to their low intrinsic luminosity they are not so
Rafael
Rebolo López