Scientists discover new Super Earth in six-planet system
By: Team Ifairer | Posted: 20-04-2020
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The researchers noted that hundreds of multi-planetary systems are known, but only a dozen contain six planets or more. The presence of six planets orbiting HD 158259 thus already makes this system remarkable, but it not its most interesting feature: what makes it exceptional is its regularity, they said.
The period ratio of any two subsequent planets is close to 3:2. This means that as the first planet - the one closest to the star - completes three orbits, the second one completes about two. As this second planet completes three orbits, the third completes about two, and so on. This situation is better understood in the general framework of "resonances", which plays a key role in the architecture of planetary systems.
Several planets are said to be in resonance when they find themselves in the same configuration periodically, after completing a potentially different number of orbits, the researchers explained. "This is comparable to several musicians beating distinct rythms, yet who beat at the same time at the beginning of each bar," said Nathan C Hara, a researcher at UNIGE, and first author of the study. Planets can also be close to the resonance, but not exactly within. This is the case of the planets of HD 158259, the researchers said.