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TOPIC: Solar System formation


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Posts: 129147
Date:
Solar System's Debris Disc
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Title: The History of the Solar System's Debris Disc: Observable Properties of the Kuiper Belt
Authors: Mark Booth (1), Mark C. Wyatt (1), Alessandro Morbidelli (2), Amaya Moro-Martín (3 and 4), Harold F. Levison (5) ((1) IoA, Cambridge University, UK, (2) OCA, Nice, France, (3) Centro de Astrobiologia - CSIC/INTA, Madrid, Spain, (4) Princeton University, USA, (5) SWRI, Boulder, USA)

The Nice model of Gomes et al. (2005) suggests that the migration of the giant planets caused a planetesimal clearing event which led to the Late Heavy Bombardment (LHB) at 880 Myr. Here we investigate the IR emission from the Kuiper belt during the history of the Solar System as described by the Nice model. We describe a method for easily converting the results of n-body planetesimal simulations into observational properties (assuming black-body grains and a single size distribution) and further modify this method to improve its realism (using realistic grain properties and a three-phase size distribution). We compare our results with observed debris discs and evaluate the plausibility of detecting an LHB-like process in extrasolar systems. Recent surveys have shown that 4% of stars exhibit 24 um excess and 16% exhibit 70 um excess. We show that the Solar System would have been amongst the brightest of these systems before the LHB at both 24 and 70 um. We find a significant increase in 24 um emission during the LHB, which rapidly drops off and becomes undetectable within 30 Myr, whereas the 70 um emission remains detectable until 360 Myr after the LHB. Comparison with the statistics of debris disc evolution shows that such depletion events must be rare occurring around less than 12% of Sun-like stars and with this level of incidence we would expect approximately 1 of the 413 Sun-like, field stars so far detected to have a 24 um excess to be currently going through an LHB. We also find that collisional processes are important in the Solar System before the LHB and that parameters for weak Kuiper belt objects are inconsistent with the Nice model interpretation of the LHB.

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Posts: 129147
Date:
Solar System formation
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Mercure, Mars, Vénus, la Terre : le choc des planètes !
Des collisions entre Mercure, Mars, Vénus et la Terre sont-elles envisageables? Pour répondre à cette question, l'équipe de l'Institut de mécanique céleste et de calcul des éphémérides (Observatoire de Paris/UPMC/INSU-CNRS) menée par l'astronome Jacques Laskar vient de réaliser une étude statistique inédite sur l'évolution du Système solaire. Dans 1 % des cas environ, les calculs conduisent à des collisions entre planètes ou entre une planète et le Soleil en moins de 5 milliards d'années. Ces résultats sont publiés dans la revue Nature datée du 11 juin 2009.

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-- Edited by Blobrana on Wednesday 10th of June 2009 08:03:14 PM

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L

Posts: 129147
Date:
Solar System evolution
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Astronomers calculate there is a tiny chance that Mars or Venus could collide with Earth - though it would not happen for at least a billion years.
The finding comes from simulations to show how orbits of planets might evolve billions of years into the future.
But the calculated chances of such events occurring are tiny.
Writing in the journal Nature, a team led by Jacques Laskar shows there is also a chance Mercury could strike Venus and merge into a larger planet.

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L

Posts: 129147
Date:
RE: Solar System formation
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Our solar system has a potentially violent future. New computer simulations reveal a slight chance that a disruption of planetary orbits could lead to a collision of Earth with Mercury, Mars or Venus in the next few billion years.

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Title: Existence of collisional trajectories of Mercury, Mars and Venus with the Earth
Authors: J. Laskar & M. Gastineau

It has been established that, owing to the proximity of a resonance with Jupiter, Mercury's eccentricity can be pumped to values large enough to allow collision with Venus within 5 Gyr. This conclusion, however, was established either with averaged equations that are not appropriate near the collisions or with non-relativistic models in which the resonance effect is greatly enhanced by a decrease of the perihelion velocity of Mercury. In these previous studies, the Earth's orbit was essentially unaffected. Here we report numerical simulations of the evolution of the Solar System over 5 Gyr, including contributions from the Moon and general relativity. In a set of 2,501 orbits with initial conditions that are in agreement with our present knowledge of the parameters of the Solar System, we found, as in previous studies, that one per cent of the solutions lead to a large increase in Mercury's eccentricity - an increase large enough to allow collisions with Venus or the Sun. More surprisingly, in one of these high-eccentricity solutions, a subsequent decrease in Mercury's eccentricity induces a transfer of angular momentum from the giant planets that destabilises all the terrestrial planets approx 3.34 Gyr from now, with possible collisions of Mercury, Mars or Venus with the Earth.

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Posts: 129147
Date:
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Putting an apparent end to all the theories on the origin of solar system, astronomers have claimed that it actually emerged from a "well-blended soup of dust and gas".
A team at natural history museum of Denmark has based its findings on the measurements of the levels of titanium in meteorites from Moon, Mars, and inclusions in meteorites that are thought to be the oldest rocks in the solar system.

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Looking at the planets of the solar system, you could be forgiven for thinking that if they do belong to the same family, it is by adoption rather than kinship. Not so: the story of the solar system's birth reveals that they are blood siblings, all created from the same molecular cloud whose collapse formed the sun. You might also think that these disparate bodies are scattered across the solar system without rhyme or reason. But move any piece of the solar system today, or try to add anything more, and the whole construction would be thrown fatally out of kilter. So how exactly did this delicate architecture come to be?

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Posts: 129147
Date:
Solar Nebula
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Title: A Shocking Solar Nebula?
Authors: Kurt Liffman

It has been suggested that shock waves in the solar nebula formed the high temperature materials observed in meteorites and comets. It is shown that the temperatures at the inner rim of the solar nebula could have been high enough over a sufficient length of time to produce chondrules, CAIs, refractory dust grains and other high-temperature materials observed in comets and meteorites.
The solar bipolar jet flow may have produced an enrichment of 16O in the solar nebula over time and the chondrule oxygen isotopic reservoirs are possibly due to temporal changes in the relative position of the inner edge of the solar nebula and the subsequent strength of the solar bipolar jet flow. As such, nebula heating models, such as the shock model, are not required to explain the formation of most high-temperature chondritic components.

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Posts: 129147
Date:
RE: Solar System formation
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Line up Mercury, Venus, Earth and Mars according to their distance from the sun and you'll see their size distribution is close to symmetrical, with the two largest planets between the two smallest. That would be no coincidence - if the pattern emerged from a debris ring around the sun.
Brad Hansen of the University of California, Los Angeles, built a numerical simulation to explore how a ring of rocky material in the early solar system could have evolved into the planets. He found that two larger planets typically form near the inner and outer edges of the ring, corresponding to Venus and Earth. A number of smaller bodies also form within the ring. These are typically scattered away by the larger two, but if they experience collisions on the way, they can end up in stable orbits similar to those of Mercury and Mars. Once beyond the ring, they cannot acquire mass and so remain pint-sized.

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