Dust bombardment can explain the extremely elongated shape of 1I/'Oumuamua and the lack of interstellar objects
Abstract
Asteroid 1I/'Oumuamua is the first observed interstellar object. Its light-curve amplitude indicates that the object is highly elongated with an axial ratio of at least 5:1. The absence of such elongated asteroids in the Solar system and the apparent lack of observed interstellar objects are intriguing problems. Here we show that 'Oumuamua may have originated as a slightly elongated asteroid about 500 × 300 m in size. Surface erosion, caused by interstellar dust bombardment, subsequently increased the axial ratio. Simply travelling through the interstellar medium for 0.03 to 2 Gyr would have sufficed to give 1I its present shape. Passing through a 10 pc dust cloud with a grain density of 10-23 g cm-3 at 50 km s-1 would have had a similar effect on 'Oumuamua's form. Smaller objects of around 100 m in diameter can travel the Galactic disc for merely 30 Myr before they are disrupted. This could explain the small number of interstellar objects observed to date.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2019
- DOI:
- 10.1093/mnrasl/sly244
- arXiv:
- arXiv:1812.11334
- Bibcode:
- 2019MNRAS.484L..75V
- Keywords:
-
- comets: general;
- minor planets;
- asteroids: general;
- asteroids: individual: 1I/2017 U1 ('Oumuamua);
- <italic>(ISM:)</italic> dust;
- extinction;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 4 pages, 4 figures