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[en] Although it is by no means clear that the Titius--Bode law of planetary distances is indeed a ''law'' (even though there are enticing indications), it is proposed that if one assumes that the law is a ''law'' and that the planets obey it, then this argues against recent large-scale evolution in the solar system. Put another way: one can believe in the Titius--Bode law or in recent large-scale evolution or in neither of them. But it appears difficult to believe in both of them
[en] The cold classical population of the Kuiper Belt exhibits a wide variety of unique physical characteristics, which collectively suggest that its dynamical coherence has been maintained throughout the solar system's lifetime. Simultaneously, the retention of the cold population's relatively unexcited orbital state has remained a mystery, especially in the context of a solar system formation model, that is driven by a transient period of instability, where Neptune is temporarily eccentric. Here, we show that the cold belt can survive the instability, and its dynamical structure can be reproduced. We develop a simple analytical model for secular excitation of cold Kuiper Belt objects and show that comparatively fast apsidal precession and nodal recession of Neptune, during the eccentric phase, are essential for preservation of an unexcited state in the cold classical region. Subsequently, we confirm our results with self-consistent N-body simulations. We further show that contamination of the hot classical and scattered populations by objects of similar nature to that of cold classicals has been instrumental in shaping the vast physical diversity inherent to the Kuiper Belt.
[en] The purpose of this paper is to outline the principles of some of the fascinating techniques which are employed currently to determine events and their chronologies over the past 4.5 b.y. The rocks assist in this task in several ways. A variety of discernible changes which occur in the chemical composition and solid state structure of rocks are indicative of specific evolutionary events during their life time, as objects exposed in free space or as buried to different depths in the planetary regoliths. Some of these records are indicative of processes occurring in the very early history of the solar system. Rocks record the low and high energy environmental radiation, often with sensitivity and resolution comparable to the modern sophisticated electronic detectors. Some of these varied records involve rare constants such as radioactive decay and erosion/fragmentation of surfaces. A record of such events can be used to establish time-scales. Thus the extraterrestrial rocks provide a record of the various influences/stresses they are subjected to; the electromagnetic and particle radiations and impacts of solid objects. Further, some of these events allow one to determine their chronology. In solar system palaeontology, 'time' is the independent variable but it is needed as an ordering parameter to classify the past events. Rocks not only record the events but they also keep a track of the independent variable, 'time'. (author)
[en] We have analyzed the first 3.75 years of data from the Taiwanese American Occultation Survey (TAOS). TAOS monitors bright stars to search for occultations by Kuiper Belt objects (KBOs). This data set comprises 5 x 105 star hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO occultations were found in this data set. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan and Sari, Kenyon and Bromley, Benavidez and Campo Bagatin, and Fraser. A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an occultation survey. Our results suggest that the KBO population is composed of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.
[en] The question about possible structure of outer (beyond Neptune) regions of the Solar system is studied within the scope of the new cosmogonical model of formation of planetary systems. It is shown that under certain conditions the evolutionary process in zones of the protoplane ary cloud beyond Neptune may lead to formation of an asteroid belt but not to formation of a planet. The hypothesis is stated that at present unknown asteroid belts exist in this region. Pluto is assumed to be an asteroid of one of these belts. This hypothesis is a development of Cameron's idea (1962) about the possibility of existence of considerable amount of matter immediately beyond the Neptune orbit
[en] This chapter discusses some of the main effects of the interaction of planets with remnant planetesimal disks, after the disappearance of the gas. It focuses on planet migration and its possible outcomes. In particular, we discuss the possibility that the migration of the planets leads them into an unstable configuration which changes drastically the structure of the system. The late heavy bombardment (LHB) of the terrestrial planets, occurring 650 Myr after planet formation, is a strong indication that this kind of evolution occurred in our solar system. Other stars show evidence of intense comet showers, which may indicate that LHB-analogs are ongoing in those systems at the current time
[en] In the recent years, the 'Nice' model of solar system formation has attained an unprecedented level of success in reproducing much of the observed orbital architecture of the solar system by evolving the planets to their current locations from a more compact configuration. Within the context of this model, the formation of the classical Kuiper Belt requires a phase during which the ice giants have a high eccentricity. An outstanding question of this model is the initial configuration from which the solar system started out. Recent work has shown that multi-resonant initial conditions can serve as good candidates, as they naturally prevent vigorous type-II migration. In this paper, we use analytical arguments, as well as self-consistent numerical N-body simulations to identify fully resonant initial conditions, whose dynamical evolution is characterized by an eccentric phase of the ice giants, as well as planetary scattering. We find a total of eight such initial conditions. Four of these primordial states are compatible with the canonical 'Nice' model, while the others imply slightly different evolutions. The results presented here should prove useful in further development of a comprehensive model for solar system formation.
[en] We have obtained a full suite of Spitzer observations to characterize the debris disk around HR 8799 and to explore how its properties are related to the recently discovered set of three massive planets orbiting the star. We distinguish three components to the debris system: (1) warm dust (T ∼ 150 K) orbiting within the innermost planet; (2) a broad zone of cold dust (T ∼ 45 K) with a sharp inner edge orbiting just outside the outermost planet and presumably sculpted by it; and (3) a dramatic halo of small grains originating in the cold dust component. The high level of dynamical activity implied by this halo may arise due to enhanced gravitational stirring by the massive planets. The relatively young age of HR 8799 places it in an important early stage of development and may provide some help in understanding the interaction of planets and planetary debris, an important process in the evolution of our own solar system.
[en] The problem of Solar system origin is discussed within the framework of the model of the Sun and protoplanet disk formation in the case of protoplanet cloud compression. During compression cloud density in its centre increases faster than at the edge which results in the separation of a nucleus with the mass equalling 1% cloud mass. After nucleus formation from its outer layers,a disk starts to form. The above mechanism of protoplanet disk formation does not contradict the data obtained in the course of studying meteorites and Halleys comet