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uni'wissen 01-2014_ENG

Prof. Dr. Svetlana Berdyugina Berdyugina is deputy director of the Kiepenheuer Institute for Solar Physics and professor of physics at the University of Freiburg. Her research focuses mainly on cosmic effects that polarize light – such as magnetic fields on stars or gas clouds in planetary systems. Berdyugina studied physics in St. Petersburg, Russia, and served as professor of astrophysics in Oulu, Finland, and at ETH Zurich, Switzerland, before coming to Freiburg in 2008. She is involved in a project to build the world’s largest optical telescope: “Colossus” will have a mirror measuring 74 meters in diameter and be capable of detecting civili- zations on faraway planets. In September 2014 she will present her research at the TEDx Conference in Maui, Hawaii, USA. Photo: private Further Reading Berdyugina, S. V. (2011): Polarimetry of cool atmospheres: From the sun to exoplanets. In: Kuhn, J. R. / Harrington, D. M. / Lin, H. / Berdyugina, S. V. / Trujillo-Bueno, J. / Keil, S. L. / Rimmele, T. (Eds.): Solar polarization workshop 6. Orem, pp. 219–235. (= Astronomical Society of the Pacific Conference Series 437). Berdyugina, S. V. / Berdyugin, A. V. / Fluri, D. M./Piirola, V. (2011): Polarized reflected light from the exoplanet HD 189733 b: First multicolor observations and confirmation of detection. In: The Astrophysical Journal Letters 728 / 1, L6. confirming the blue color with another method and with help from the Hubble Space Telescope. To See Where No One Has Seen Before Besides its color, however, the blue planet does not have much in common with Earth. It is larger than Jupiter, probably consists entirely of gas, and orbits its sun so closely that it doesn’t even take three days to complete the journey. The radiation and temperatures on HD 189733 b are therefore extreme – no environment for life as we know it on Earth. “Our main goal is to study the composition of the atmospheres of exoplanets,” says Beryugina, “but the next step will be to look for biological signatures – on Earth-like planets in the habitable zones of foreign solar systems.” The habitable zone consists of the narrow belt around a star in which planets can support water in liquid form. It cannot be too hot or too cold. An atmosphere containing water polarizes light differently than one that is completely dry. In theory, however, any conceivable molecule could be detected by means of polarimetry. Svetlana Berdyugina will thus not settle for merely finding water. She wants to search for indisputable signs of extraterrestrial life. “We must first learn to identify life that functions differently than on Earth – life based on substances other than water and carbon,” says Berdyugina. “Initially, we are therefore on the lookout for organic molecules of the simplest forms of life we know.” With the help of a prototype of the “Innovative Polarimeter” (InnoPol), she and her team measured the polarimetric profiles of pigments typically used by bacteria for photosynthesis. Examples of such pigments are chlorophyll, which makes plants green, or carotenoids, to which carrots owe their orange color, or anthocyanin, which gives blackberries their dark bluish-violet hue. Biologists at the University of Aarhus in Den- mark are collecting these bacteria with special airplanes and growing them in the lab. Together with astrobiologists from the University of Hawaii, USA – the location of one of the telescopes Berdyugina is using – the team from Freiburg measured these colorful colonies of bacteria with the InnoPol. The result: “The polarimetric signatures of these photosynthetic molecules are unmistakable.” There is no mistaking red bacteria for red dust, for instance, even though they are both the same color when seen in visible light. InnoPol might just be sensitive enough to measure polarization that is typical of particular molecules in the atmosphere of exoplanets. That would mean evidence of life outside of our solar system – though probably not on HD 189733 b, the other blue planet. “We must first learn to identify life that functions differently than on Earth.” 7