Lithopanspermia through gas-assisted capture of interstellar objects

[BjarneModerator Super Nova]

Planet seeding and lithopanspermia through gas-assisted capture of interstellar objects

Planet formation begins with collisional-growth of small planetesimals accumulating into larger-ones. Such growth occurs while planetesimals are embedded in a gaseous protoplanetary-disk. However, small-planetesimals experience collisions and gas-drag that lead to their destruction on short-timescales, not allowing, or requiring fine-tuned conditions for the efficient growth of ~meter-size planetesimals. Here we show that small (up-to 0.1-10 km-size) unbound interstellar-objects passing through a gaseous protoplanetary-disk can be efficiently captured to become embedded in the disk. ‘Seeding’ of such planetesimals then catalyze further planetary-growth into planetary embryos, and potentially alleviate the main-challenges with the meter-size growth-“barrier”. Moreover, planetesimal-capture provides a far-more efficient route for lithopanspermia than previously thought, and ∼10⁴ interstellar objects such as the recently detected 1I/2017-U1 (‘Oumuamua) could have been captured, and become part of the young Solar System.

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