What pushed 'Oumuamua away from the Sun?
Eight answers, none aheadNone is ahead yet. See what would settle it.
Where it stands
Eight answers have been proposed. None is ahead on the evidence yet. Eight are still possible.
Why it matters
The non-gravitational acceleration is the measurement every reading has to reproduce, and it was detected at 30 sigma with no visible gas or dust to account for it[1][2]. The answer fixes the composition, and it is the one property that made an artificial reading arguable at all[3]. An independent re-fit confirms the signal and its radial direction, so the question is the mechanism, not the measurement[4].
Answers 8
History
- Micheli et al. puts forward: outgassing of water or another undetected ordinary volatile from an icy body, below the limits of every…
- Bialy & Loeb puts forward: solar radiation pressure on an artificial lightsail.
- Micheli et al. puts forward: the acceleration is an artefact of the astrometry or the orbit fit, not a real force.
- Trilling et al.: spitzer limits CO and CO2 to about ten thousand times below what the outgassing model needed; water was not…Against: Outgassing of water or another undetected ordinary volatile from an icy body, below the limits of every…
- Micheli et al.: outgassing was the only mechanism the discovery team found physically viable, if the body had comet-like…For: Outgassing of water or another undetected ordinary volatile from an icy body, below the limits of every…
- Enriquez et al.: no narrowband radio emission was found from 72 MHz to 11.6 GHz, to 0.08 W at Green Bank.Against: Solar radiation pressure on an artificial lightsail.
- Taylor et al.: the light curve shows no secular change in spin, which is in tension with how outgassing comets spin up.Against: Outgassing of water or another undetected ordinary volatile from an icy body, below the limits of every…
- Hoang & Loeb: cooling by the escaping hydrogen would cut the volume of warm ice and the gas budget by a factor of five to…Against: Release of molecular hydrogen made by cosmic rays inside an ordinary water-ice body, freed as the ice warmed…
- Bergner & Seligman: laboratory work shows hydrogen is produced in irradiated water ice and released over a range of temperatures;…For: Release of molecular hydrogen made by cosmic rays inside an ordinary water-ice body, freed as the ice warmed…
- Bergner & Seligman: the model code and data are public, so the cooling objection can be tested directly.For: Release of molecular hydrogen made by cosmic rays inside an ordinary water-ice body, freed as the ice warmed…
- Spada: an independent re-fit confirms the acceleration and finds it radial.Against: The acceleration is an artefact of the astrometry or the orbit fit, not a real force.
- Seligman et al.: small near-Earth asteroids with no visible activity show non-gravitational accelerations too large for the…For: Outgassing of water or another undetected ordinary volatile from an icy body, below the limits of every…
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