Trojans in stable chaotic motion

The orbits of 13 Trojan asteroids have been calculated numerically in the m odel of the outer solar system for a time interval of 100 million years. Fo r these asteroids Milani et al. (1997) determined Lyapunov times less than 100 000 years and introduced the notion "asteroids in stable chaotic motion ". We studied the dynamical behavior of these Trojan asteroids (except the asteroid Thersites which escaped after 26 million years) within 11 time int ervals - i.e. subintervals of the whole time - by means of: (1) a numerical frequency analysis (2) the root mean square (r.m.s.) of the orbital elemen ts and (3) the proper elements. For each time interval we compared the root mean squares of the orbital elements (a, e and i) with the corresponding p roper element. It turned out that the variations of the proper elements e(p ) in the different time intervals are correlated with the corresponding r.m .s.(e); this is not the case for sin I-p with r.m.s.(i).