Constraints on the Density and Internal Strength of 1I/'Oumuamua

Andrew McNeill, David E. Trilling, Michael Mommert

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


1I/'Oumuamua was discovered by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS 1) on 2017 October 19. Unlike all previously discovered minor planets, this object was determined to have eccentricity e > 1.0, suggesting an interstellar origin. Since this discovery and within the limited window of opportunity, several photometric and spectroscopic studies of the object have been made. Using the measured light curve amplitudes and rotation periods we find that, under the assumption of a triaxial ellipsoid, a density range 1500 < ρ < 2800 kg m-3 matches the observations and no significant cohesive strength is required. We also determine that an aspect ratio of 6 ± 1:1 is most likely after accounting for phase-Angle effects and considering the potential effect of surface properties. This elongation is still remarkable, but less than some other estimates.

Original languageEnglish (US)
Article numberL1
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Apr 10 2018


  • asteroids: individual (1I/Ouamuamua) - techniques: photometric
  • methods: statistical - minor planets

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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