Editor's Summary
3 April 2008
Combing the sky for 'earths'
The current count of extrasolar planets (on planetquest.jpl.nasa.gov) stands at 277, none of them Earth-like. Most were detected as a Doppler shift in stellar spectral lines, a method that 'sees' planets down to about five times the mass of the Earth. If Earth-sized planets are to be revealed by this observational approach, better Doppler shift resolution via improved spectrograph wavelength calibration will be required. A newly developed instrument, the 'astro-comb', achieves just that by adapting the laser frequency comb, a device that has revolutionized laboratory spectroscopy, to the needs of astrophysics. This involves reducing the density of comb lines, without compromising spectral resolution. A performance test of the astro-comb is reported in this issue, and in May 2008, the new device joins the search for 'exoearths' in earnest.
Authors: Abstractions
doi:10.1038/7187xiiib
News and Views: Extrasolar planets: With a coarse-tooth comb
The search for Earth-like planets outside our Solar System is bedevilled by the lack of an adequate frequency standard for calibrating starlight. Tweaking existing laser 'frequency combs' could be a way forward.
Gordon Walker
doi:10.1038/452538a
Letter: A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s-1
Chih-Hao Li, Andrew J. Benedick, Peter Fendel, Alexander G. Glenday, Franz X. Kärtner, David F. Phillips, Dimitar Sasselov, Andrew Szentgyorgyi & Ronald L. Walsworth
doi:10.1038/nature06854
