The dangerous border of the 5:2 mean motion resonance     

Zoran Kne?evi?  Andrea Milani  Paolo Farinella 《Planetary and Space Science》1997,45(12):1581-1585

After discovering that asteroid (2953) Vysheslavia, a Koronis family member, has a typical dynamical lifetime of the order of 10 Myr only against “falling” into the 5:2 Kirkwood gap and ending up in a hyperbolic orbit (Milani and Farinella, 1995. Icarus 114, 209–212), we decided to repeat the same study for two other asteroids, 1991 UA₂ and 1993 FR₅₈, lying also very close to the outer edge of the same resonance. The orbital elements of these bodies were not yet accurate enough and we appealed to observers, both professional and amateur, to obtain more astrometric data. Eight groups in three different countries carried out observations, and as a result the Minor Planet Center could derive updated, accurate orbits for both objects. Here we report on the preliminary results of our study. Whereas the long-term behavior of 1991 UA₂ looks fairly regular and stable, 1993 FR₅₈ exhibits a typical “stable chaos” behavior; nevertheless, it does not end up in the resonance within a time span of 50 Myr. On the other hand, its fictitious clones, placed just 3–4 × 10⁻³ AU closer to the resonance, undergo large irregular semimajor axis changes, fall into the resonance and escape on a timescale <1 Myr.  相似文献   

Secular variations of major planets' orbital elements     

Zoran Knežević 《Celestial Mechanics and Dynamical Astronomy》1986,38(2):123-138

The secular variations of the orbital elements of principal planets are calculated by means of classical Lagrange's method. The terms of the second order with respect to mass, introduced by Hill (1897) and Brouwer and van Woerkom (1950), have been taken into account as well. The best contemporary values of planetary masses and mean elements (Bretagnon, 1982) served as the starting data set for this calculation. Considerable differences with respect to previous solutions of the same type (Brouwer and van Woerkom, 1950: Sharaf and Boudnikova, 1967) were found in the coefficientsA ₅₅,A ₅₆, andA ₆₆ of the system of equations of variation of elements and in the roots (frequencies)r ₅ andr ₆. Results are compared with some higher order/higher degree solutions and their accuracy discussed. It is confirmed that the solutions like that of Brouwer and van Woerkom, although not being completely inferior to all higher order/higher degree ones, can be considered as the first approximation only. Hence, they should be replaced by more accurate ones (Duriez, 1979: Bretagnon, 1984: Laskar, 1984) in the future applications.  相似文献   

A review of empirical orthogonal function (EOF) with an emphasis on the co-seismic crustal deformation analysis     

Neha  Pasari  Sumanta 《Natural Hazards》2022,110(1):29-56

Natural Hazards - An automatic, transparent, and regular way to investigate and analyze the spatiotemporal variations in a large, unstructured, and high-dimensional data set is highly desirable in...  相似文献