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10.12.2019, Mainz, Germany

Specialty glass helps to discover exoplanets

Swiss Nobel Prize Winners in Physics 2019 use spectrometers to measure star movements/ optical glasses are from SCHOTT
Each year, the Nobel Prizes are awarded on December 10, the anniversary of the death of the benefactor Alfred Nobel. This year’s Nobel Prize in Physics has been split: It goes to James Peebles for his theoretical contributions to cosmology as well as to the Swiss astrophysicists Michel Mayor and Didier Queloz. The reason is that the researchers at the University of Geneva have succeeded in discovering the first exoplanet around a sun-like star using the so-called radial velocity method. This was achieved by using special high-resolution spectrometers, whose precise measurements are performed using highly refractive optical glasses from SCHOTT.

When a planet orbits around a star, its gravity causes small movements that leave traces in the star's light spectrum. For example, when it moves towards us, its light shifts to shorter wavelengths; when it moves away, the light takes on longer wavelengths. The two scientists Mayor and Queloz, discovered this pattern 1995 in the spectrum of 51 Pegasi, a star fifty light-years away from Earth. With their radial velocity method, they provided evidence of the first known planet, a Jupiter-sized exoplanet orbiting a sun-like star.

The discovery was made possible by high-resolution spectrometers. These were used to determine the velocity of the stars with an accuracy of 1 m/s from the Doppler shift of the spectral lines in star spectra. This corresponds to one three-hundred-millionth of the speed of light, and the wavelengths of the spectral lines must be measured with extreme accuracy. The discovery was made possible by high-resolution spectrometers, which can determine the wavelengths of the spectral lines with an accuracy of 1m/s. This corresponds to one three-hundred-millionth of the speed of light. With the measured movements, it is possible to determine, among other things, the mass and orbital elements of the planets orbiting them. Such measurements require stable environmental conditions in laboratories and cannot be performed in spectrometers directly integrated into telescopes. For several of the spectroscopic instruments used by Mayor and Queloz at the University of Geneva, the Swiss company FISBA AG has developed special optical components with which the light can be precisely coupled and uncoupled into the connecting fibers between the telescope and the spectrometer. Also, besides the ‘fiber links,’ the company also manufactured the ‘cross dispersers’ consisting of prisms.

In order to meet the required specifications, the optical designers needed a material with good transmission in the wavelength range of the spectrometer and quite high dispersion. “After comparing many glasses, we chose SCHOTT glass F2HT because it offered the best combination of properties for the application,” explains Eckhard Langenbach, Senior Optical Design Expert at FISBA AG.

According to the Nobel Prize Committee, the discoveries made by this year’s Nobel Prize winners in physics have changed our perception of the cosmos. While Mayor and Queloz have successfully searched Earth’s cosmic neighborhood for unknown planets with high-tech instruments and glass from SCHOTT, astrophysicists want to explore the atmosphere of exoplanets from 2025 onwards and even find life outside our solar system. Then the largest eye in the world, the Extremely Large Telescope (ELT) of the European Southern Observatory (ESO) will have ‘First Light.’ SCHOTT is also involved in this superlative astronomy project with its components. The technology group is supplying ZERODUR® glass-ceramic as a mirror substrate for four of the five mirrors of the ELT telescope, including all 798 substrates for the giant 39 m primary mirror.      

More information
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Optical glasses SCHOTT:

SCHOTT is a leading international technology group in the areas of specialty glass, glass-ceramics and related high-tech materials. With over 130 years of experience, the company is an innovative partner to many industries, including the home appliance, pharma, electronics, optics, life sciences, automotive and aviation industries. SCHOTT has a global presence with production sites and sales offices in 34 countries. In the 2017/2018 fiscal year, the group generated sales of EUR 2.08 billion with over 15,500 employees. SCHOTT AG has its headquarters in Mainz (Germany) and is solely owned by the Carl Zeiss Foundation. This is one of the oldest private and largest science-promoting foundations in Germany. As a foundation company, SCHOTT assumes special responsibility for its employees, society and the environment.
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