Possible patterns in the distribution of planetary formation regions |
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| Authors: | J L Ortiz F Moreno A Molina P Santos Sanz P J Gutiérrez |
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| Institution: | Instituto de Astrofísica de Andalucía, CSIC, Apt 3004, 18080 Granada, Spain;Departamento de Física Aplicada, Universidad de Granada, Granada, Spain |
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| Abstract: | Eris, an object larger than Pluto, is known to reside in the transneptunian region further away than Pluto. One can wonder whether its semimajor orbital axis fits in a generalized Titius–Bode law, in the same way as Pluto does. We performed a new least-squares fit to a generalized Titius–Bode law including Eris and found that not only does Eris fit in the trend, but also the correlation coefficient improves. In addition, there is a remarkable symmetry of the location of the planetary formation regions with respect to Jupiter when the natural logarithm of the heliocentric distance is used as the metric. The issue of whether the observed patterns have some physical meaning or are due to mere chance is addressed using a Monte Carlo approach identical to that of Lynch. Although the probability of chance occurrence is highly dependent on the way in which the random configurations of synthetic planetary systems are selected, we find that in all reasonable scenarios of random planetary systems the probability of chance occurrence of the observed patterns is small (below 1 per cent in most cases). If the trend were used as a prediction tool, one might expect another planet or dwarf planet or a swarm of bodies with semimajor orbital axis of 120 ± 20 au. Simple calculations show that the protoplanetary nebula most likely had enough mass to allow the accretion of at least a dwarf planet at that distance. We also found that if the surface density of the nebula decayed with heliocentric distance ( r ) as a power of ?2, the regular spacing in ln r in the Solar system could be a natural consequence of the existence of a threshold mass for planetary formation. |
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| Keywords: | Kuiper Belt Solar system: formation Solar system: general |
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