THE ORBIT OF ASBOLUS

Effects of the close approach to Saturn in 1702


The following are plots of the osculating elements of the orbit of 8405 Asbolus during the period 1600-2020, covering a total of 384 consecutive dates separated by 400 days each. All the angular quantities are with respect to the ecliptic and equinox of J2000.

The effects of the close approach to Saturn in 1702 can be observed in these graphs, producing abrupt "jumps" in the otherwise normal periodic perturbations and small secular drifts. The minimum distance between Saturn and Asbolus was 0.466 AU on May 12, 1702.

Perturbations are of two types: secular (cumulative) and periodic, or usually a combination of both, the amplitude of a particular periodic perturbation increasing with time. It usually happens that a secular drift is really a periodic perturbation of very long period, so before reaching conclusions about the instability of Asbolus' orbit, plots for longer time-spans and a better orbit determination are needed.

The effects shown here can be compared with similar graphs of the orbit of 1998SG35 and the orbit of 1999UG5, and show that Asbolus has a much more stable orbit; in fact, no other centaur (with the possible exception of 1995SN55, for which we'll have to wait for a better orbit estimation) shows variations of such magnitude in such a short time-span, or so close to the present, as SG35.

As can be seen from the plot of the semi-major axis, the encounter "shrinked" the orbit of Asbolus, reducing its period of revolution from nearly 81 years to 75-76 years, which is its value at present.

The elements used for the numerical integration were taken from E. Bowell's "Astorb" database and are fitted to observations covering 1899 days.

A similar study of the orbital changes suffered by Chiron in a minor encounter with Saturn in 1899 is in preparation.
 
 

Figure 1: semi-major axis


 

Figure 2: minimum solar distance


 

Figure 3: mean sidereal motion


 

Figure 4: sidereal period of revolution


 

Figure 5: argument of perihelion


 

Figure 6: orbital eccentricity


 

Figure 7: longitude of perihelion


 

Figure 8: orbital inclination


 

Figure 9: longitude of the ascending node

 


 
 
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