Science: combing the universe for planets

David A Aguilar (CfA), hypothetical world with 2 moons, UniverseToday

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That's right, literally combing with an astro-comb to find planets outside our solar system. Currently scientists are just looking for Venus to test the technology and make sure it works (Gizmag: Astronomers use astro-comb to seek Earth-like exoplanets).

The Walsworth Group reports:

We have developed a new technique using laser frequency combs to improve the accuracy and stability of wavelength calibration of astrophysical spectrographs by up to two orders of magnitude. This "astro-comb" will provide a key advance in the resolution of changes in astrophysical Doppler shifts and redshifts, and thus may allow the discovery of Earth-like planets and new measurements of astrophysical dynamics relevant to cosmology.

Both of the leading techniques to find exoplanets rely on the planet's very small effect on its star. The radial velocity technique measures the star's "wobble" (and hence Doppler shift) due to the planet's gravitational pull as it circles; while the transit technique measures the dimming of a star's light as a planet passes in front of it. With current technology, both of these techniques can identify relatively large planets that have a noticeable effect on their star. Detection of the very small Doppler shifts (<10 cm/s) induced by smaller, rocky planets, like Earth and Mars, will require improved wavelength calibration that can only be provided by astro-combs.

For Physics.org's report on the topic, take a look at this article.

Another group, Telescopio Nazionale Galileo (TNG), has published images of their setup and reports on the TNG+Harps-N system.

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astro-comb laser setup, TNG

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-- Marge