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Discovery, Orbit and Orbital Evolution of the Distant Object (463368) 2012 VU85

Wlodarczyk I., Černis K., Boyle R. P.

Acta Astronomica

2017

Vol. 67, No. 1

81--102

We present the discovery and time evolution of orbital elements of the distant Centaur-type object (463368) 2012 VU85. From all 2135 distant objects listed in the Minor Planet Center we select all 347 numbered distant object and integrate their equations of motion in the 1 Gyr forward and backward integration. The asteroid (463368) 2012 VU85 lies on the border of the group of 347 distant objects, which have a semimajor axis about 44 a.u., eccentricity 0.1 and inclination between 0° and 30°. We show that after 1 Gyr of forward integration, about half of the objects are expelled from the Solar System, \ie their median lifetime is about 1 Gyr. We note that the long-lived distant objects are mainly located between the regions where Neptune controls aphelia of asteroids and the asteroids are in the mean motion resonance 2/3 with Neptune. We find eight almost regular approaches of clones of the asteroid (463368) 2012 VU85 to Neptune and several generally shorter in time regular approaches to Uranus. For other outer planets we did not detect any approaches below 5 a.u. for a period of 15 000 yr in forward and backward integrations. In our calculations we find eight episodes, each lasting about 3000 yr when the value of inclination oscillates around its average. These changes look similar to the changes of semimajor axis during the occurrence of orbital mean motion resonance with a planet. We find that half of the clones of the asteroid (463368) 2012 VU85 remain in the Solar System for a forward integration of 44 Myr, and for a backward integration of 34 Myr. This is a significantly shorter escape time as compared to the group of distant objects. Almost all long-lived clones have value of Tisserand parameter with respect to Neptune smaller than 3 during the whole 1 Gyr forward and backward integrations. This implies that there are several clones of the asteroid (463368) 2012 VU85 that cross the orbits of Neptune and Uranus. We find many orbital mean motion resonances lasting up to several Myr in the motion of the asteroid (463368) 2012 VU85. According to our computations the presence of the Kozai resonance protects the asteroid from the close approaches with Uranus and Neptune. The Lyapunov time for the asteroid (463368) 2012 VU85 is equal to 4260 years.

The Potentially Hazardous Asteroid (410777) 2009 FD

Wlodarczyk I.

Acta Astronomica

2015

Vol. 65, No. 2

215--231

The asteroid (410777) 2009 FD is placed at the top of the JPL NASA Sentry Risk Table. We show that the predicted probability of the potential impact of the asteroid (410777) 2009 FD in fact depends on (i): used methods of selection and weighing of observational data, (ii): adopted dynamical model with included non-gravitational effects in the motion of asteroid based on cometary approach, and considerably weaker depends on (iii): the used model of the Solar System with different number of massive asteroids as potential perturbers. We computed impact solutions of the asteroid (410777) 2009 FD based on its 296 optical observations from February 24, 2009 to April 02, 2014 and one radar observation from April 07, 2014. We used the freely available ORBFIT Software Package and studied the future evolution of the orbit of (410777) 2009 FD searching for close approaches with the Earth and for the possible impacts up to the year 2200. According to our study the impacts are possible in the years: 2185, 2186, 2190, 2191, 2192, 2194, 2196, and 2198, provided the non-gravitational parameter A2 in the range of (-46.0,+3.0)×10-15 a.u./d2, with the gap between (-25.0,-11.0)×10-15 a.u./d2.