Astronomers wondered about the existence of satellites of satellites

Theoretical calculations showed that if the moon is sufficiently large and rotate quite far from their planet, then it can be own “subline”.

Астрономы задумались о существовании спутников у спутников

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The heavenly body that moves around the planet, holding its gravity, called the companion, and only in the Solar system known to them more than 180. And recently, astronomers have discovered the first accespoint distant exoplanets: apparently, it’s quite common in space objects. But could they be satellites from the satellites themselves? If we talk about the Solar system, anything like that are not yet discovered, but perhaps there is somewhere else whether their trajectories are stable in principle?

Astronomers Kollmeier juna (Juna Kollmeier) from the Carnegie Institute and Sean Raymond (Raymond Sean) from the University of Bordeaux called these bodies “sublunary” (submoons). In a paper presented at the online library of preprints arXiv.orgthey lead the preliminary calculations of the conditions under which this is possible. According to scientists, “subline” can remain stable if its dimensions are small (on the order of ten kilometers in radius), and her “mother” satellite, on the contrary, massive enough (at least 1000 miles) and rotates at a great distance from its planet.

Moreover, even if today the moons of the Solar system such “sublin” and no, they could exist at some period of the past. Theoretically need to satisfy the conditions of Titan and yapet Saturn, Callisto, Jupiter and even our own Moon. Even more promising from this point of view can be called ekzotik, recently discovered a planet Kepler-b 1625, the size of which is ten times higher than the size of the Earth.