(a, e) plot of >4000 asteroids selected from astorb.dat, for which the J2/1 critical angle was checked:
Alternating asteroids are grouped in a cluster with low-a and low-e, is there any dynamical reason for such behaviour?
Regularly circulating asteroids in J2/1 resonance selected by Roig and by Broz. There is a cluster with a \doteq 3.25 AU, e < 0.1 and scattered in i, which was NOT selected by Roig, even though they are librating nicely (of course, not around 3.27 AU, because the libration center is moved to 3.25 AU for low-e orbits). Why these asteroids are not considered as resonant ones?
We do not know yet, what are their lifetimes (they can be pretty high, if the orbits miss the region, where secular resonances overlap). Can we explain this cluster by asteroids originated in the background population and drifting by Yarkovsky effect?! That is the question...
See also transport maps of background asteroids (with this group superimposed): r21_back-dmap_prn71.ps, r21_back-dmap_prn72.ps.
An example of one asteroid from the low-a, e group: J2/1 critical angle, osculating semimajor axis, eccentricity and sine of inclination, all on the same timescale 10.000 yr. Orbits of all such asteroids look similarly: sigmaJ2/1 changes more slowly when increases and more faster when decreases, a oscillates around 3.25 AU, oscillations of i are quite small.
