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New technique to hunt for Earth-like planets


German researchers have developed a new technique that will help astronomers hunt for Earth-like planets around distant stars with ease.

The team has successfully demonstrated how a solar telescope can be combined with a piece of technology that has already taken the physics world by storm – the laser frequency comb (LFC).

The LFC is a tool for measuring the colour or frequency of light and has been responsible for generating some of the most precise measurements ever made.

An LFC is created by a laser that emits continuous pulses of light, containing millions of different colours, often spanning almost the entire visible spectrum.

In their study, the researchers from the Max Planck Institute of Quantum Optics, the Kiepenheuer Institute for Solar Physics and the University Observatory Munich performed an analysis on the Sun by combining sunlight with the light of an LFC.

Both sources of light were injected into a single optical fibre which then delivered the light to a spectrograph for analysis.

"An important aspect of our work is that we use a single-mode fibre which takes advantage of the wave nature of light to enable a very clean and stable beam at its output," explained lead author Rafael Probst from the Max Planck Institute of Quantum Optics.

The results show that if the LFC light and the sunlight are simultaneously fed through the same single-mode fibre, the obtained calibration precision improves by about a factor of 100 over a temporally separated fibre transmission.

"We then obtain a calibration precision that keeps up with the best calibration precision ever obtained on an astrophysical spectrograph, and we even see considerable potential for further improvement," Probst added.

The researchers envisage using the new technique to not only study the star at the centre of our solar system, but stars much further away from us, particularly to find Earth-like planets that may be orbiting around them.

"It is expected the technique will allow a spectral analysis of distant stars with unprecedented accuracy, as well as advance research in other areas of astrophysics," the authors concluded.

The paper was published in the New Journal of Physics.