Results 1 - 10 of 1131
Results 1 - 10 of 1131. Search took: 0.023 seconds
|Sort by: date | relevance|
[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] Almost ten years after its launch and after 6000 million kilometers, the spacecraft Rosetta reached its destination orbit about 20 kilometers Comet 67P / Churyumov-Gerasimenko and make down to its surface to Philae module. With this initiative, the European Space Agency aims who know better how the solar system was in its origins, with the information it has collected and will collect this celestial body remains almost unchanged since billions of years. The probe continues its journey. (Author)
[en] Full text: Many celestial bodies in our solar system may possess a fluid layer such as an liquid core or a subsurface ocean. In such a case, at first order one should expect the liquid to simply follow the mean rotation of the solid layers. However, due to the complex orbital dynamics of planets, e.g. precession, notation, liberation, departure from the state of pure solid body rotation is expected. The induced flow may result in a dissipation of energy, an enhanced heat transfer or an induced magnetic field on various time scales which may be observable. In the present study we focus on the flow induced by longitudinal liberation in planetary cores and subsurface oceans. We show that depending on the equatorial flattening of the liquid-solid interface the induced flow can be laminar or turbulent, which should have significantly different signature in observable such as the induced magnetic field. (author)
[en] Full text: CCD photometric observations in BVRI-bands for different minor bodies of the Solar System were carried out on different nights between the 2011 and 2013 apparitions from Mitterschöpfl (Austria) using the 1.5 m Figl Observatory telescope. Photometric studies will be presented, especially color indices of the different bodies, comparisons and possible new detections of multiple bodies, such as a binary one. The light curves are plotted using data from these observations to detect the amplitudes; also synodic rotation periods in filtered photometry (especially in the R-band) are computed and discussed here. (author)
[en] Full text: Planet formation models have been developed during the last years in order to try to reproduce and predict observations of the solar system and extra solar planets. Using a modular planetary system formation model combining an extended core-accretion model including migration, disc evolution and gap formation with an N-Body part for the dynamical interactions we perform population synthesis calculations in order to investigate the effect of the formation of more than one planet in the same protoplanetary disc. We show the modifications of masses and semi-major axis through competition and gravitational interactions varying the number of forming planets. (author)
[en] The field of exoplanetary science has seen a dramatic improvement in sensitivity to terrestrial planets over recent years. Such discoveries have been a key feature of results from the Kepler mission which utilizes the transit method to determine the size of the planet. These discoveries have resulted in a corresponding interest in the topic of the Habitable Zone and the search for potential Earth analogs. Within the solar system, there is a clear dichotomy between Venus and Earth in terms of atmospheric evolution, likely the result of the large difference (approximately a factor of two) in incident flux from the Sun. Since Venus is 95% of the Earth's radius in size, it is impossible to distinguish between these two planets based only on size. In this Letter we discuss planetary insolation in the context of atmospheric erosion and runaway greenhouse limits for planets similar to Venus. We define a ''Venus Zone'' in which the planet is more likely to be a Venus analog rather than an Earth analog. We identify 43 potential Venus analogs with an occurrence rate (η♀) of 0.32−0.07+0.05 and 0.45−0.09+0.06 for M dwarfs and GK dwarfs, respectively
[en] This study presents a survey of abundance distribution and isotopic composition of the ammonia found incorporated in the kerogen-like insoluble material of selected carbonaceous chondrite meteorites; the ammonia was released upon hydrothermal treatment at 300°C and 100 MPa. With the exception of Allende, a metamorphosed and highly altered stone, all the insoluble organic materials (IOM) of the meteorites analyzed released significant amounts of ammonia, which varied from over 4 μg mg–1 for the Orgueil IOM to 0.5 μg mg–1 for that of Tagish Lake; the IOM of the pristine Antarctica find GRA95229 remains the most rich in freeable ammonia with 10 μg mg–1. While the amounts of IOM bound ammonia do not appear to vary between meteorites with a recognizable trend, a possible consequence of long terrestrial exposure of some of the stones, we found that the δ15N composition of the ammonia-carrying materials is clearly distinctive of meteorite types and may reflect a preservation of the original 15N distribution of pre- and proto-solar materials.
[en] A relatively massive and moderately eccentric disk of trans-Neptunian objects (TNOs) can effectively counteract apse precession induced by the outer planets, and in the process shepherd highly eccentric members of its population into nearly stationary configurations that are antialigned with the disk itself. We were sufficiently intrigued by this remarkable feature to embark on an extensive exploration of the full spatial dynamics sustained by the combined action of giant planets and a massive trans-Neptunian debris disk. In the process, we identified ranges of disk mass, eccentricity, and precession rate that allow apse-clustered populations that faithfully reproduce key orbital properties of the much-discussed TNO population. The shepherding disk hypothesis is, to be sure, complementary to any potential ninth member of the solar system pantheon, and could obviate the need for it altogether. We discuss its essential ingredients in the context of solar system formation and evolution, and argue for their naturalness in view of the growing body of observational and theoretical knowledge about self-gravitating disks around massive bodies, extra-solar debris disks included.