470785 (2008 UX299) vs 233771 (2008 TO124)

These two main belt asteroids have similar obit parameters.

Their orbit condition codes are 1 and 0 respectively

Using the JPL Small-Body Database Browser, we can see:

470785 (2008 UX299)

Classification: Main-belt Asteroid          SPK-ID: 2470785

[ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 8 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1009684932114735 2.8551e-07   a 2.689930801283626 1.8626e-07 au q 2.418332541434887 9.1801e-07 au i 3.214698487892873 1.5513e-05 deg node 305.753597645791 0.00017107 deg peri 87.42148259454721 0.00027647 deg M 13.75396504670777 0.00023418 deg tp 2457938.934770288169 (2017-Jul-04.43477029) 0.0010426 JED period 1611.42496879941 4.41 0.00016737 4.582e-07 d yr n .2234047547793786 2.3204e-08 deg/d Q 2.961529061132366 2.0506e-07 au

Orbit Determination Parameters    # obs. used (total)      45      data-arc span      4277 days (11.71 yr)      first obs. used      2004-12-15      last obs. used      2016-08-31      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      1      fit RMS      .58441      data source      ORB      producer      Otto Matic      solution date      2017-Apr-09 07:28:47   Additional Information  Earth MOID = 1.42674 au   Jupiter MOID = 2.43518 au   T_jup = 3.363

233771 (2008 TO124)

Classification: Main-belt Asteroid          SPK-ID: 2233771

[ Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters | Discovery Circumstances | Close-Approach Data ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 8 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1009140923237167 8.811e-08   a 2.690005559689887 3.9217e-08 au q 2.41854609028803 2.3857e-07 au i 3.214945766069064 1.0959e-05 deg node 305.7617498385058 0.00017798 deg peri 87.60982730687554 0.0001892 deg M 353.2000614611609 6.4573e-05 deg tp 2458030.939020972455 (2017-Oct-04.43902097) 0.00028938 JED period 1611.492146214952 4.41 3.5241e-05 9.648e-08 d yr n .2233954418242512 4.8853e-09 deg/d Q 2.961465029091743 4.3175e-08 au

Orbit Determination Parameters    # obs. used (total)      112      data-arc span      7084 days (19.39 yr)      first obs. used      1995-11-18      last obs. used      2015-04-11      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      fit RMS      .60277      data source      ORB      producer      Otto Matic      solution date      2017-Apr-10 21:12:24   Additional Information  Earth MOID = 1.42701 au   Jupiter MOID = 2.43425 au   T_jup = 3.363

I tried to simulate their behavior in the past to investigate whether they might be related.

Simulation set-up

Mercury6 Integrator

reference:

J.E.Chambers (1999) 

A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799.

           Integration parameters
           ----------------------

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2458000.5000000 days
   Integration stop  epoch:      -100000000.0000000
   Output interval:                     100.000
   Output precision:                 medium

   Initial timestep:                0.050 days
   Accuracy parameter:              1.0000E-12
   Central mass:                    1.0000E+00 solar masses
   J_2:                              0.0000E+00
   J_4:                              0.0000E+00
   J_6:                              0.0000E+00
   Ejection distance:               1.0000E+02 AU
   Radius of central body:          5.0000E-03 AU

In order to perform the simulation I generated 30 clones for each asteroids (same average orbital parameters as the nominal ones and standard deviation almost about the one calculated by JPL).

Thus, I evaluated 900 couples to check whether there was a moment in the past when two clones were very near with a very low relative velocity.

In particular, I used two arbitrary thresholds to detect interesting couples:

• distance less than 1 Lunar Distance - about 0.0020 AU
• relative velocity less than 1 m/s

The clone generation and the couples evaluation have been done using scripts written in R.

Simulation Results
The results are interesting because 819 out of 900 couples satisfy the thresholds mentioned above.

Distance between clones (km):
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.   sd
    105    1200    2190    3270    3230  119000  9030
Relative velocity (m/s) when at minimum distance:
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.   sd
  0.034   0.092   0.120   0.140   0.150   0.940  0.09
Time of minimum distance (Years):
   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.   sd
-272820  -75850  -62761  -74560  -56070  -18177  41444

In a graphical form:

same as above but with a little more  "zoom" ...:

The couple that went very near
Note that the time step is 100 days (this is consistent with a physical separation):

Conclusion
While this does not prove that the asteroids originated from a common body,  it seems that this is certainly a possibility.

Kind Regards,
Alessandro Odasso