Even on habitable exoplanets, the relevance was much less likely to allow the emergence of obvious life as previously accepted. To this result, a research group around giovanni covone came from the university of naples in the analysis of the conditions for oxygen-based photosynthesis. On no one of the almost 5000 exoplanets we are currently considered to be potentially habitable – could therefore only theoretically create a comprehensive biosphere, which is based on the earth on oxygener photosynthesis. Thus, they could only find one single, which may at least approach the determined conditions – kepler-442B.
Flow water is not enough
Since the beginning of the 1990s, the first exoplanets have been found outside of our solar system, the question of a potential second earth was in the foreground. The concept of the habitable zone was then introduced, that is, the area around a star in which liquid water could occur on a rock plan – the most important prerequisite for the emergence of life on earth. How roughly the tension width is also in this zone, the fact illustrates that in the solar system not only the earth, but also the lifelong mars and depending on the definition even the venus lie in this zone. With the inclusion of the question of whether there could be a rich biosphere there, the team around covone now expands the definition – and at the same time limits the zone significantly.
The research team has dedicated itself to the question of how much energy known exoplanets from their star gets and whether organisms, as we can produce them from the earth, could produce efficient nutrients and molecular oxygen. Both are elementary building blocks for life, as we know it, justify your approach now. If a star is only half as heib, as our sun, can not arrive enough radiation in the right wavelength on a possible exoplanet, they have determined them. Oxygene photosynthesis goods there possible, but for a rich biosphere it was not enough. On exoplanets around the particularly numerous but still cooler red dwarf stars, on the other hand, was not even enough radiation to initiate photosynthesis at all.
Stars that are heard as our sun, meanwhile, even significantly more radiation on possible exoplanets, but usually they were not old enough to give life the time to create and develop. Overall, their work suggests that earth-tooth conditions could be even rarer on other planets than hoped so far, covone said. Your study draw significant limits for important parameters and laying "unfortunately" close that these are pretty tight. The complete research work has been published in the trade magazine monthly notices of the royal astronomical society.