Galactic Orbits of Different Galactic Population Objects

Abstract

It is evident that the knowledge of not only positions and velocities of objects belonging to different populations but also their osculating galactic orbits can clarify the structure and history of our Galaxy. Action variables being adiabatic invariants are especially useful for these purposes ( Binney, May 1986 ). One of them is a usual area integral (and it can be found without any orbit calculation ). The second action variable is connected with an energy integral but for 3-D orbits and arbitrary potentials it cannot be found analitically. Eccentricities resulting from orbit calculations can be used here ( Lynden-Bell 1963 ). Comparison of eccentricities defined with different ways shown that differences between them are practically negligible ( Kutuzov 1985, 1987 ). As for the third action variable and the corresponding third isolating integral orbit calculations can confirm its existence and control the validity of various approximations. Numerical technique allowing to find it and working at any potential is now in progress ( Binney, Kumar 1993 ) .