• DOI:10.3847/2041-8213/ab05df
• Corpus ID: 119008824

Could 1I/’Oumuamua be an Icy Fractal Aggregate?

@article{MoroMartin2019Could1B,
  title={Could 1I/’Oumuamua be an Icy Fractal Aggregate?},
  author={Amaya Moro-Mart'in},
  journal={The Astrophysical Journal},
  year={2019}
}

• A. Moro-Mart'in
• Published 11 February 2019
• Geology, Physics
• The Astrophysical Journal

1I/'Oumuamua was the first interstellar interloper that has been detected and it showed a non-gravitational acceleration (Micheli et al. 2018) that cannot be accounted for by outgassing, given the strict upper limits to outgassing resulting from Spitzer observations, unless the relative abundances of the common volatiles are very different from those in comets (Trilling et al. 2018). As an alternative, Bialy & Loeb (2018) have suggested that its peculiar acceleration is due to radiation pressure, requiring a planar sheet geometry of an unknown natural or artificially origin. Here we assess whether the internal structure of 1I/'Oumuamua, rather than its geometry, could support a radiation-pressure driven scenario. We adopt a mass fractal structure and find that the type of aggregate that could yield the required area-to-mass ratio would have to be extraordinarily porous with a density $\sim$ 10$^{-5}$ g cm$^{-3}$. Such porous aggregates can naturally arise from the collisional grow of icy dust particles beyond the snowline of a protoplanetary disk and here we propose that 1I/'Oumuamua might belong to this population. This is a hypothesis worth investigating because, if this were the case, 1I/'Oumuamua could have truly opened a new observation window to study the building blocks of planets around other stars and this could set unprecedented constraints on planet formation models.