Fifth giant ex-planet of the outer Solar System: characteristics and   remnants
  In recent years it has coming to light that the early outer Solar System likely might have somewhat more planets than today. However, to date there is unknown what a former giant planet might in fact have represented and where its orbit may certainly have located. Using the originally suggested relations, we have found the reasonable orbital and physical characteristics of the icy giant ex-planet, which in the past may have orbited the Sun about in the halfway between Saturn and Uranus. Validity of the results obtained here is supported by a feasibility of these relations to other objects of the outer Solar System. A possible linkage between the fifth giant ex-planet and the puzzling objects of the outer Solar System such as the rings of Saturn and the irregular moons Triton and Phoebe existing today is briefly discussed. 
Yury I. Rogozin
astro-ph.EP