Long-term evolution of Oort Cloud comets: methods and comparisons
نویسندگان
چکیده
منابع مشابه
The mass disruption of Oort cloud comets.
We have calculated the number of dormant, nearly isotropic Oort cloud comets in the solar system by (i) combining orbital distribution models with statistical models of dormant comet discoveries by well-defined surveys and (ii) comparing the model results to observations of a population of dormant comets. Dynamical models that assume that comets are not destroyed predict that we should have dis...
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از گذشته تا کنون، تحقیقات بسیاری صورت گرفته است که همگی به گونه ای بر مثمر ثمر بودن استفاده از استراتژی های یادگیری لغت در یک زبان بیگانه اذعان داشته اند. این تحقیق به بررسی تاثیر دو روش مختلف آموزش واژگان انگلیسی (کلیدی و بافتی) بر تلفظ و دانش لغوی فراگیران ایرانی زیر متوسط زبان انگلیسی و بر ماندگاری آن در حافظه می پردازد. به این منظور، تعداد شصت نفر از زبان آموزان ایرانی هشت تا چهارده ساله با...
15 صفحه اولPerihelion Evolution of Observed New Comets Implies the Dominance of the Galactic Tide in Making Oort Cloud Comets Discernable
For an Oort cloud comet to be seen as a new comet, its perihelion must be moved from a point exterior to the loss cylinder boundary to a point interior to observable limits in a single orbit. The galactic tide can do this continuously, in a non-impulsive manner. Near-parabolic comets, with specific angular momentum H ∝ √q, will most easily be made observable. Therefore, to reduce the perihelion...
متن کاملJupiter – friend or foe? III : the Oort cloud comets
It has long been assumed that the planet Jupiter acts as a giant shield, significantly lowering the impact rate of minor bodies on Earth. However, until recently, very little work had been carried out examining the role played by Jupiter in determining the frequency of such collisions. In this work, the third of a series of papers, we examine the degree to which the impact rate on Earth resulti...
متن کاملIsotopic abundances of carbon and nitrogen in Jupiter-family and Oort Cloud comets
The 12C14N/12C15N and 12C14N/13C14N isotopic ratios are determined for the first time in a Jupiter-family comet, 88P/1981 Q1 Howell, and in the chemically peculiar Oort Cloud comet C/1999 S4 (LINEAR). By comparing these measurements to previous ones derived for six other Oort Cloud comets (including one of Halley-type), we find that both the carbon and nitrogen isotopic ratios are constant with...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 2001
ISSN: 0035-8711,1365-2966
DOI: 10.1046/j.1365-8711.2001.04297.x