(5201) Ferraz-Mello (=1983 XF)
                                                                                                           © S.Ferraz-Mello (IAG-USP)

Unusual asteroid discovered by Ted Bowell at Anderson Mesa Station (Lowell Observatory) on December 1st, 1983. May be an inactive Jupiter- family comet (T=2.972) in a very eccentric orbit (e=0.54). The orbit perihelion (q= 1.53 AU) and aphelion (Q= 4.82 AU) lie near the orbits of Mars and Jupiter, respectively.

Orbital Elements (IAU/MPC list of unusual objects)

Where is it now? (Allow 1-2 minutes to download the orbits. After that, you may play and see the next approaches to Jupiter and Mars.)

What's its current position in the sky?

Magnitude and Size: The absolute magnitude is H=14.8. The effective diameter may be estimated through  the formula: log D = 3.12 - 0.5 log A - 0.2 H. The albedo of asteroids in that region of the belt are A~0.03-0.06 and thus D~6-8 km.

The next approaches to Jupiter and Mars:

             MJD 53993.0  (Sep. 14, 2006)     0.451 AU (67.5 Gm) from Mars
             MJD 54872.1  (Feb. 09, 2009)     0.358 AU (53.5 Gm) from Jupiter

Approaches in the next millenium.
Approaches in the past 3 millenia.
Visual magnitude during the next years:

Dynamics: The asteroid is currently (and will remain till ca. 2300) in the 2/1 resonance with Jupiter as shown by the evolution of the critical angle:

Librations in the past 3 millenia.
Libration diagram: Motion of the angle s in polar coordinates in the next 690 years. The distance from the center is the eccentricity and the polar angle is s. There are two episodes of libration separated by a little more than one century of retrograde circulation around t=2400.

A succession of approaches to Jupiter and Mars: CHAOS!
        The Lyapunov time lies in the range 25-40 yrs.

While s is far from 180 deg, the asteroid cannot approach Jupiter; however at every half libration period, s approaches 180 deg, and at those dates a close approach to Jupiter becomes possible. The libration period is close to 175 yrs, and we may count 8 approaches in the next 600 years, most of them below 0.3 AU and the last of them close to 0.2 AU. The motion lies at the border of the 2/1 resonance and the above libration diagram shows that at each half libration period, the motion approaches a saddle point and is chaotic. As a consequence the actual evolution after some approaches is unpredictable. In several runs before the one shown above, the behavior was only "almost" the same. Always the closest approximation to Jupiter occurs in 500 to 700 years, with values that may be even much closer that the one shown above. The transition shown after year 2700 was seen in every simulation, always showing a large increase in the semi-major axis.

The simulation included all planets from Venus to Neptune. The distance to Mars after yr 2700 is not shown since close approaches no longer occur because the large semi-major axis and smaller eccentricity. The labels of the curves are the same shown in the plot of the next approaches.

After! The unpredictability of the motion makes any run for a longer time senseless. However, even if only of qualitative interest, in the present simulation, the motion in the millennium starting in yr 3000, after the big transition shown in the above figure,  is co-orbital:

The projection of the motion on the ecliptic is shown in a heliocentric reference frame co-rotating with Jupiter. Jupiter's position  is shown by a cross.

The past: A monotonous succession of very-high-amplitude s-librations. The last circulation happened around yr -800. No approaches to Jupiter less than 0.3 AU in this period (the last one, 0.365 AU, in 1926.36). Many close approaches (down to 0.07 AU) to Mars.

(The labels of the curves are the same shown in the plot showing the next approaches.)

References in the literature: