Know The Unseen

Introduction  The Kuiper belt is the relic of the primordial planetesimal disk, shaped by various dynamical and collisional processes that occurred when the Solar System was evolving towards its present structure. Thus, studying the origin of the structure of the Kuiper belt is important because it can unveil the history of the formation and evolution of the giant planets and, more in general, of the proto-Solar System. The main properties of the Kuiper belt that require an explanation in the framework of the primordial evolution of the Solar System are: (The following list is presented in no particular order.)  i) The existence of conspicuous populations of objects in the main mean motion resonances (MMRs) with Neptune (2:3, 3:5, 4:7, 1:2, 2:5, etc.). Resonant objects form obvious vertical structures in a semi-major axis (a) versus eccentricity (e) plot, for example, see Fig. 1A. The resonant objects represent a significant fraction of the total trans-neptunian population. T...

5 Planet Systems Over the last decade, evidence has mounted that the solar system’s observed state can be favorably reproduced in the context of an instability-driven dynamical evolution model, such as the “Nice” model. To date, all successful realizations of instability models have concentrated on evolving the four giant planets onto their current orbits from a more compact configuration. Simultaneously, the possibility of forming and ejecting additional planets has been discussed, but never successfully implemented. Here we show that a large array of 5-planet (2 gas giants + 3 ice giants) multi-resonant initial states can lead to an adequate formation of the outer solar system, featuring an ejection of an ice giant during a phase of instability. Particularly, our simulations demonstrate that the eigenmodes which characterize the outer solar system’s secular dynamics can be closely matched with a 5-planet model. Furthermore, provided that the ejection timescale of the extra planet is ...

The most remarkable feature of Antiope is that it consists of two components of almost equal size (the difference in mass is less than 2.5%[12]), making it a truly "double" asteroid. Its binary nature was discovered on 10 August 2000 by a group of astronomers using adaptive optics at the Keck Telescope on Mauna Kea.[10] Before this, IRAS observations had suggested that the asteroid was 120 km in diameter.[1] Orbital Antiope orbits in the outer third of the core region of the asteroid belt, and is a member of the Themis family. Since each component is about 86±1 km across, with their centers separated by only about 171 kilometers,[4] the gap separating the two halves is about the same as the diameter of each component. As a result, the two bodies orbit around the common center of mass which lies in the space between them. The orbital period is approximately 16.50 hours, and the eccentricity below 0.006.[4] Every several years, a period of mutual occultations occurs when the as...