Amor 2016 CK246 - cometary origin and hilda like resonance

 Mercury6 Integration Parameters

)O+_06 Integration parameters  (WARNING: Do not delete this line!!)

) Lines beginning with `)' are ignored.

)---------------------------------------------------------------------

) Important integration parameters:

)---------------------------------------------------------------------

 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS

 start time (days)= 2461221.5

 stop time (days) = -1e8

 output interval (days) = 100

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Backward Integration Results

This asteroid today is an Amor that has an almost perfect 3:2 resonance with Jupiter.

Due to the high eccentricity it was already suspected to have a cometary origin and the backward simulation confirms this idea.

The asteroid entered the solar system about 58000 years ago following a capture by Uranus.

Since then it had countless encounters with Saturn, Jupiter, Mars and Earth.

We should not take the detailed timing and specific past trajectory at face value because the evolution is very chaotic due to close encounters.

However, at least from a qualitative point of view, the results are interesting.

Hilda like Jupiter Resonance

An interesting plot shows the 3:2 resonance with Jupiter:

the “cleanest” capture into a classical (persistent) 3:2 libration looks to happen very late, at about:

$t\approx -0.0065\text{Myr}$ ≈ 6,500 years ago

We can recognize three phases:

• For $t\lesssim -0.03\; Myr\; (left\; side),$$\Phi$ essentially fills $[-180^\circ,180^\circ)$that’s what circulation / strong chaos looks like when wrapped.

• Between roughly $-0.03$ and $-0.007$ Myr, you see intermittent structured bands with repeated wrap hits (temporary resonance episodes).

• After about $-0.0065$ Myr, the trace stops making those ±180° wrap excursions and becomes a bounded oscillation with a much smaller amplitude → that’s the visual hallmark of sustained libration.

Other plots: