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arXiv:1810.11490astro-ph.EP

Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration?

Shmuel Bialy, Abraham Loeb

Abstract

`Oumuamua (1I/2017 U1) is the first object of interstellar origin observed in the Solar System. Recently, \citet{Micheli2018} reported that `Oumuamua showed deviations from a Keplerian orbit at a high statistical significance. The observed trajectory is best explained by an excess radial acceleration $Δa \propto r^{-2}$, where $r$ is the distance of `Oumuamua from the Sun. Such an acceleration is naturally expected for comets, driven by the evaporating material. However, recent observational and theoretical studies imply that `Oumuamua is not an active comet. We explore the possibility that the excess acceleration results from Solar radiation pressure. The required mass-to-area ratio is $(m/A)\approx 0.1$ g cm$^{-2}$. For a thin sheet this requires a thickness of $\approx 0.3-0.9$ mm. We find that although extremely thin, such an object would survive an interstellar travel over Galactic distances of $\sim 5$ kpc, withstanding collisions with gas and dust-grains as well as stresses from rotation and tidal forces. We discuss the possible origins of such an object. Our general results apply to any light probes designed for interstellar travel.

arXiv comments
To be published in "The Astrophysical Journal Letters" on November 12, 2018
Journal reference
DOI
doi:10.3847/2041-8213/aaeda8
Subjects
astro-ph.EPEarth and Planetary Astrophysics astro-ph.GAAstrophysics of Galaxies

On Hacker News

Linked by 6 identifiable commenters in 6 comments across 6 threads, from Nov 2018 to Jan 2021. Found in 1 HN submission from Nov 2018 to Nov 2018. Open submission discussions.

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Discussed in comments6 threads

  1. Why do we assume extraterrestrials might want to visit us? 1 comment

    • This author has also proposed that the solar system has already been visited: "‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization."[0] The rest of the paper covers the possibility that the ‘Oumuamua object was sent…

      stereoabuseView on HNParent context

  2. Harvard Professor Says Alien Technology Visited Earth in 2017 1 comment

    • Comets show similar "weird" accelerations. Its not aliens, its probably just outgassing! Here's the first public paper I could find off hand on the topic. The acceleration due to outgassing of 67P/Churyumov–Gerasimenko (of Rosetta spacecraft fame)…

      techdragonView on HNParent context

  3. Harvard’s top astronomer says an alien ship may be among us 1 comment

    • Here's the paper Loeb co-authored ... Could Solar Radiation Pressure Explain 'Oumuamua's Peculiar Acceleration? https://arxiv.org/abs/1810.11490v4

      _rpdView on HNParent context

  4. A Harvard Astronomer on the Interstellar Object ‘Oumuamua 1 comment

    • The following October, Avi Loeb, the chair of Harvard’s astronomy department, co-wrote a paper (with a Harvard postdoctoral fellow, Shmuel Bialy) that examined ‘Oumuamua’s “peculiar acceleration” and suggested that the object “may be a fully operational probe sent intentionally…

      nkurzView on HNParent context

  5. Aliens Might Have Sent Cigar-Shaped Probe to Monitor Earth, Study Finds 1 comment
  6. Interstellar object may have been an alien probe, Harvard paper claims 1 comment

    • Well, the paper[0] spends ~98% of the time not claiming that. I think I thought those pictures of it were what it looked like! but "The large variations on the light curves indicate that ʻOumuamua is a highly elongated object... However, the size and shape have not been directly…

      yesenadamView on HNParent context

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