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Jupiter – friend or foe? II: the Centaurs

Horner, J. and Jones, B. W. (2009). Jupiter – friend or foe? II: the Centaurs. International Journal of Astrobiology, 8(2) pp. 75–80.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1017/S1473550408004357
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Abstract

It has long been assumed that the planet Jupiter acts as a giant shield, signi?cantly lowering the impact rate of minor bodies upon the Earth, and thus enabling the development and evolution of life in a collisional environment which is not overly hostile. In other words, it is thought that thanks to Jupiter, mass extinctions have been sufficiently infrequent that the biosphere has been able to diversify and prosper. However, in the past, little work has been carried out to examine the validity of this idea. In the second of a series of papers, we examine the degree to which the impact risk resulting from objects on Centaur-like orbits is affected by the presence of a giant planet, in an attempt to fully understand the impact regime under which life on Earth has developed. The Centaurs are a population of ice-rich bodies which move on dynamically unstable orbits in the outer Solar system. The largest Centaurs known are several hundred kilometres in diameter, and it is certain that a great number of kilometre or sub-kilometre sized Centaurs still await discovery. These objects move on orbits which bring them closer to the Sun than Neptune, although they remain beyond the orbit of Jupiter at all times, and have their origins in the vast reservoir of debris known as the Edgeworth-Kuiper belt that extends beyond Neptune. Over time, the giant planets perturb the Centaurs, sending a significant fraction into the inner Solar System where they become visible as short-period comets. In this work, we obtain results which show that the presence of a giant planet can act to signi?cantly change the impact rate of short-period comets on the Earth, and that such planets often actually increase the impact flux greatly over that which would be expected were a giant planet not present.



Item Type: Journal Article
Copyright Holders: 2009 Cambridge University Press
ISSN: 1473-5504
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNot SetSTFC
Extra Information: Related papers in the series:

Jupiter - friend or foe? I: the asteroids

Jupiter - friend or foe? III: the Oort cloud comets
Keywords: Centaurs; comets; minor planets; planets and satellites; formation
Academic Unit/Department: Science > Physical Sciences
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Related URLs:
Item ID: 15498
Depositing User: Astrid Peterkin
Date Deposited: 30 Mar 2009 15:33
Last Modified: 23 Mar 2014 06:32
URI: http://oro.open.ac.uk/id/eprint/15498
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