Journal Article

On collisional capture rates of irregular satellites around the gas-giant planets and the minimum mass of the solar nebula

F. Elliott Koch and Bradley M.S. Hansen

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 416, issue 2, pages 1274-1283
Published in print September 2011 | ISSN: 0035-8711
Published online September 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.19130.x
On collisional capture rates of irregular satellites around the gas-giant planets and the minimum mass of the solar nebula

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We investigate the probability that an inelastic collision of planetesimals within the Hill sphere of the Jovian planets could explain the presence and orbits of observed irregular satellites. Capture of satellites via this mechanism is highly dependent on not only the mass of the protoplanetary disc, but also the shape of the planetesimal size distribution. We performed 2000 simulations for integrated time intervals ∼2 Myr and found that, given the currently accepted value for the minimum mass solar nebula and planetesimal number density based upon the Nesvorný et al. and Charnoz & Morbidelli size distribution dND−3.5dD, the collision rates for the different Jovian planets range between ∼0.6 and ≳170 Myr−1 for objects with radii 1 km ≤r≤ 10 km. Additionally, we found that the probability that these collisions remove enough orbital energy to yield a bound orbit was ≲10−5 and had very little dependence on the relative size of the planetesimals. Of these collisions, the collision energy between two objects was ≳103 times the gravitational binding energy for objects with radii ∼100 km. We find that capturing irregular satellites via collisions between unbound objects can only account for ∼0.1 per cent of the observed population, hence this cannot be the sole method of producing irregular satellites.

Keywords: methods: numerical; celestial mechanics; planets and satellites: dynamical evolution and stability; planets and satellites: formation; planets and satellites: general

Journal Article.  6752 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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