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: Sergei Ipatov  ( 6135 )

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« : 01 Апрель 2003, 15:08:42 »

----- Original Message -----
From: sergei ipatov
To: olkhov@mail.ru ; pcagpdir@um.mos.ru
Cc: sipatov@gmu.edu
Sent: Thursday, March 27, 2003 5:35 AM
Subject: abstracts to Tunguska-03

Dear editors.
Below you can find my abstracts to the Tunguska-03 conference.
Need I send them in Russian? If ‘yes’, please, inform me, and I shall send the Russian text.
In December Alexandr Getling told me that the deadline is April 1 and I need to send the abstracts to V.I. Zyukov. Just now I looked at Olkhovatov’s www-site and found that the deadline is March 20. Sorry for the delay.
Best regards
Sergei Ipatov
Migration of trans-Neptunian objects to the Earth
S.I. Ipatov (Institute of Applied Mathematics, Moscow; ipatov@keldysh.ru)
It is considered by many authors that the Tunguska object could be a small comet or debris of a comet. Trans-Neptunian objects (TNOs) are one of the sources of comets. As migration of TNOs to Jupiter's orbit was investigated by several authors, we have made series of runs of the orbital evolution of Jupiter-crossing objects (JCOs) under the gravitational influence of planets. The orbital evolution of about 8000 and 5400 JCOs with initial periods P<20 yr was integrated with the use of the Bulirsh-Stoer and symplectic methods, respectively. The probabilities of collisions with the Sun were different for different methods and different accuracy per integration step, but all other obtained results were similar. The simulations showed that most of the collisions of former JCOs with the terrestrial planets (these probabilities were calculated on the basis of the orbital elements obtained with a step of 500 yr) are due to a small (~0.1-1%) portion of objects that moved for several Myrs in orbits with aphelion distances Q<4.7 AU. A few bodies got inner-Earth orbits (Q<0.983 AU), Aten orbits, and Apollo orbits with semi-major axes a<2 AU, and moved in such orbits during up to tens or even hundreds Myrs. Larger (than those obtained by other scientists) mean probabilities of collisions with the terrestrial planets are caused mainly by that we considered a larger number of initial objects and among them there were objects with large collision probabilities. The analysis of the orbital evolution of TNOs and JCOs showed that a considerable portion (up to several tens of percent) of present near-Earth objects (NEOs) can be former TNOs (so they can be extinct comets). Some former comets that have moved in typical NEO orbits for millions or even hundreds of millions of years, and might have had multiple close encounters with the Sun, could have lost their mant! les, which caused their low albedo, and so change their albedo and would look like typical asteroids. Several our papers on this problem were put in http://arXiv.org/format/astro-ph/. This work was supported by RFBR (01-02-17540) and INTAS (00-240).

Виталий Ромейко
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