WAS ‘OUMUAMUA A CHUNK OF AN EXO-PLUTO?

EMILY LAKDAWALLA

The interstellar object ‘Oumuamua (11/2017 U1) was an odd duck. Its strong brightness variations suggested a pancake-like aspect ratio of 6:6:1. It also slowed more than expected — 10 times more than it would if it were a typical comet — as it exited the Solar System. Yet it exhibited no visible coma, nor a tail of either dust or gas. At a recent science workshop, Steve Desch (Arizona State University) presented a plausible scenario that accounts for all of these aspects. Desch and team member Alan Jackson (also Arizona State) investigated the sublimation behaviour of various ices common in the outer Solar System. They found that nitrogen ice could provide the right reflectivity, size and mass to reproduce ‘Oumuamua's cometary trajectory without producing any of the hallmarks of comets. Pure nitrogen-ice would…

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Australian Sky & Telescope (Digital) - 1 Issue, March 2023

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