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Friday, August 18, 2017

Asteroid 2017 DQ15

Asteroid 2017 DQ15 is a NEO (Apollo) displayed in the list of objects with a comet-like orbit maintained by Y. Fernandez.

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB
Reference: JPL 7 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .7272164269790051 1.279e-05
a 2.823784780342436 0.00011852 au
q .7702821018241148 3.8782e-06 au
i 20.18557131636563 0.00017551 deg
node 272.8777420846461 0.00046785 deg
peri 350.4179039106148 0.00040687 deg
M 22.44168793940112 0.0013623 deg
tp 2457892.456452631231
0.00026204 JED
period 1733.18857109974
n .207709654911683 1.3077e-05 deg/d
Q 4.877287458860757 0.00020471 au

Orbit Determination Parameters
   # obs. used (total)      43  
   data-arc span      187 days  
   first obs. used      2017-02-10  
   last obs. used      2017-08-16  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      5  
   fit RMS      .50315  
   data source      ORB  
   producer      Otto Matic  
   solution date      2017-Aug-17 06:19:02  

Additional Information
 Earth MOID = .22774 au 
 Jupiter MOID = .339108 au 
 T_jup = 2.792 

Based on the nominal orbital parameters and uncertainty, I generated 100 clones with an R script and then I used the Mercury6 simulator by J.E. Chambers to investigate what happened in the last 10^8 days.

Mercury6 simulator: configuration
More about the program "A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies'' can be found here.

Main integration parameters:

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2458000.5000000 days
   Integration stop  epoch:        -10^8 days
   Output interval:                     100.000 days
   Output precision:                   medium
   Initial timestep:                      0.100 days
   Accuracy parameter:             1.0000E-12
   Ejection distance:                  1.0000E+02 AU

Simulation results
As seen above, the "ejection distance" used to claim that an asteroid has arrived from the outskirts of the solar system is 100 AU.
The simulation shows that there is a good likelyhood that the asteroid has a cometary origin:
  • 47 out of 100 clones arrived from a distance greater than 100 AU in the last 10^8 days
  • 4 out of 100 clones would have "collided" with the sun 

The most recent arrival time was about 7906 B.C.
The mean arrival time was about 139274 B.C.
The less recent arrival time was about 268318 B.C.

The arrival time distribution of the 47 clones that were likely to be comets is shown below:

Kind Regards,
Alessandro Odasso

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