Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Acta Astronomica

2 Królikowska M.

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: Comets: general

Sortuj według:

Ogranicz wyniki do:

Non-Gravitational Effects in Long-Period Comets and the Size of the Oort Cloud

Królikowska M.

Acta Astronomica

2006

Vol. 56, No. 4

385--412

The influence of the non-gravitational effects on the original and future orbital elements of long-period comets and in particular on reciprocals of semi-major axes is analyzed. The new orbit determinations were performed in a homogeneous way using the basic collection of 50 nearly-parabolic comets of first class orbits. The data consist of 20 hypothetically hyperbolic comets (sample I), 11 Oort spike comets (sample II), and 19 "old" comets (sample III). The original and future reciprocals of semi-major axes for each comet were calculated for strictly gravitational case and the non-gravitational case in a fully consistent way. Clear shift of the original reciprocals of semi-major axes toward the more elliptical orbits is confirmed. The average values of the original and future energy changes due to the non-gravitational acceleration are derived for each of three samples independently. Omission of the NG effects significantly affects the position and width of the Oort spike. The shift of the Oort spike position from the standard 1/aori value of 2-4×10-5 a.u.-1 to a value greater than 5.9×10-5 a.u.-1 is discussed.

67P/Churyumov-Gerasimenko - Potential Target for the Rosetta Mission

Królikowska M.

Acta Astronomica

2003

Vol. 56, No. 2

195--208

Influence of the non-gravitational effects on the motion of short-period comet 67P/Churyumov-Gerasimenko is investigated. It was found that the normal component of the non-gravitational force exceeds the transverse one and a model of the motion including A1, A2, A3 better fits the observations than model neglecting A3. Assuming asymmetry in g(r) with respect to the perihelion the large value of displacement τ was derived (about 34 days), and very small negative value of transverse component A2 was obtained. The models of rotating non-spherical nucleus also suggest the large shift of light curve with respect to perihelion (τ≥30). The forced precession model of 67P with τ=34 days gives a prolate spheroidal shape of the rotating nucleus with axial ratio Rb/Ra=1.16, rotational period to equatorial radius Prott/Ra=4.6±1.4 hrs/km, and torque factor ftor=3×105 day/a.u. The orientation of spin axis of the nucleus and its evolution are presented. The past and the future dynamical evolution of comet 67P is also widely discussed.