486081 (2012 UX41) vs 504375 (2007 VV73) - Divorced pair?

Asteroids 486081 (2012 UX41)  504375 (2007 VV73) are two distinct objects that have a similar orbit.

I tried to investigate whether these two objects could be a divorced binary pair generating clones and simulating their past behaviour.

The answer is not conclusive but I think these two objects are interesting.

Connecting to the HORIZONS Web-Interface from JPL, you get:

486081 (2012 UX41)

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

[ show orbit diagram ]

Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB Reference: JPL 14 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1032904301220536 6.5866e-08 a 2.245458730002628 4.6918e-08 au q 2.013524331959336 1.3717e-07 au i 6.007363025544946 1.256e-05 deg node 200.7854247185886 6.8302e-05 deg peri 266.0282980023908 9.2854e-05 deg M 272.0908404992332 6.2565e-05 deg tp 2458900.614977660203 (2020-Feb-21.11497766) 0.00021456 TDB period 1229.011772734908 3.36 3.8519e-05 1.055e-07 d yr n .2929182681455487 9.1806e-09 deg/d Q 2.47739312804592 5.1764e-08 au

Orbit Determination Parameters    # obs. used (total)      47      data-arc span      4156 days (11.38 yr)      first obs. used      2005-10-07      last obs. used      2017-02-22      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .61043      source      ORB      producer      Otto Matic      solution date      2017-Apr-09 04:48:41   Additional Information  Earth MOID = 1.04097 au   Jupiter MOID = 2.63527 au   T_jup = 3.617

486081 (2012 UX41)

Classification: Main-belt Asteroid          SPK-ID: 2486081

504375 (2007 VV73)

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

[ show orbit diagram ]

Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB Reference: JPL 12 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1029111754557024 5.6919e-08 a 2.245493461895011 2.2879e-08 au q 2.014407090253301 1.2474e-07 au i 6.013781035001495 9.9051e-06 deg node 200.7565685960872 5.9357e-05 deg peri 263.9747204655452 7.9426e-05 deg M 83.6944551442494 5.1702e-05 deg tp 2458314.767063259248 (2018-Jul-15.26706326) 0.00017487 TDB period 1229.040287667593 3.36 1.8784e-05 5.143e-08 d yr n .2929114721562046 4.4767e-09 deg/d Q 2.476579833536721 2.5234e-08 au

Orbit Determination Parameters    # obs. used (total)      72      data-arc span      4241 days (11.61 yr)      first obs. used      2007-09-14      last obs. used      2019-04-25      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      norm. resid. RMS      .68836      source      ORB      producer      Otto Matic      solution date      2019-Jul-14 13:44:52   Additional Information  Earth MOID = 1.04182 au   Jupiter MOID = 2.6423 au   T_jup = 3.617

504375 (2007 VV73)

Classification: Main-belt Asteroid          SPK-ID: 2504375

Clone Generation
I generated 100 clones for both asteroids, trying to achieve the same distribution read from JPL data:

summary_2012+UX41

	Clones			Target
	mean	sd		mean	sd
q	2.01352434	1.4e-07		2.01352433	1.4e-07
e	0.10329043	7e-08		0.10329043	7e-08
i	6.00736228	1.262e-05		6.00736303	1.256e-05
peri	266.02829744	9.299e-05		266.028298	9.285e-05
node	200.78542722	6.809e-05		200.78542472	6.83e-05
tp	2458900.61498223	0.0002149		2458900.61497766	0.00021456

summary_2007+VV73

	Clones			Target
	mean	sd		mean	sd
q	2.0144071	1.3e-07		2.01440709	1.2e-07
e	0.10291117	6e-08		0.10291118	6e-08
i	6.01378178	9.84e-06		6.01378104	9.91e-06
peri	263.97471761	7.905e-05		263.97472047	7.943e-05
node	200.75657263	5.961e-05		200.7565686	5.936e-05
tp	2458314.76706963	0.00017361		2458314.76706326	0.00017487

Simulation
I used the Mercury6 simulator by John E. Chambers:
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.

algorithm: Bulirsch-Stoer
start time: 2458604.5 JD
output interval : 100 days
stop time: -5d7 days
accuracy parameter=1.d-12

Simulation Results

I used an R script to compare the resulting 10000 clone couples looking for the minimum distance ever reached.

In particular, I used the library ggplot2 by Hadley Wickham to display the graphs that you see here.

As expected, every pair is different and you can collect the resulting minimum distances (plus correspondent relative velocities) and the time of minimum distanceto get an idea about the distribution:

Minimum distance

Relative velocities (at the time of min distance) 

Time of Minimum distance

Best couple
The couple of clones that according to the simulation ever reached the minimum distance show this behaviour:

Don't be fooled by the scale, the "zeros" are not really "zeros":

About 122000 years ago, this couple was separated by a distance about 20000 km and the relative velocity was about 50 m/s

Even though the numbers are small, they are not enough to claim that this is a divorced pair (on the other hand, given the uncertainty, I am not sure if you can rule out this idea specially if you could look much more in the past).

Kind Regards,
Alessandro Odasso

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 (2017-May-18.95645263) 0.00026204 JED period 1733.18857109974 4.75 0.10912 0.0002988 d yr 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

(2012 TQ236) vs 341874 (2008 GB53)

(2012 TQ236) vs 341874 (2008 GB53)

This is another interesting couple (same simulation approach described in the previous post).

(2012 TQ236)

Classification: Main-belt Asteroid          SPK-ID: 3612103

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

[ show orbit diagram ]

Orbital Elements at Epoch 2458000.5 (2017-Sep-04.0) TDB Reference: JPL 6 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1666400181863286 5.5861e-06 a 2.181322170293682 2.3565e-06 au q 1.817826604165701 1.4148e-05 au i 3.706000259833047 2.3889e-05 deg node 130.8866173415038 0.00037736 deg peri 225.066713022466 0.0031505 deg M 207.0510430328395 0.0025163 deg tp 2458500.444927002519 (2019-Jan-16.94492700) 0.0088584 JED period 1176.73358020709 3.22 0.0019068 5.221e-06 d yr n .3059316110760132 4.9574e-07 deg/d Q 2.544817736421663 2.7491e-06 au

Orbit Determination Parameters    # obs. used (total)      25      data-arc span      1078 days (2.95 yr)      first obs. used      2012-09-23      last obs. used      2015-09-06      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      3      fit RMS      .65133      data source      ORB      producer      Otto Matic      solution date      2017-Apr-07 17:13:15   Additional Information  Earth MOID = .814749 au   Jupiter MOID = 2.88145 au   T_jup = 3.660

341874 (2008 GB53)

Classification: Main-belt Asteroid          SPK-ID: 2341874

[ 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 4 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .1669528069531998 1.1233e-07 a 2.180875946944555 3.0388e-08 au q 1.816772585985444 2.5263e-07 au i 3.706556681959036 1.2083e-05 deg node 130.8943547687225 0.0001365 deg peri 225.0440620302201 0.00014182 deg M 182.8634290772902 3.7363e-05 deg tp 2458579.329428649479 (2019-Apr-05.82942865) 0.00013018 JED period 1176.372519962207 3.22 2.4587e-05 6.732e-08 d yr n .306025509684267 6.3962e-09 deg/d Q 2.544979307903666 3.5462e-08 au

Orbit Determination Parameters    # obs. used (total)      78      data-arc span      5842 days (15.99 yr)      first obs. used      2001-02-02      last obs. used      2017-01-31      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      0      fit RMS      .48759      data source      ORB      producer      Otto Matic      solution date      2017-Apr-10 08:47:34   Additional Information  Earth MOID = .813692 au   Jupiter MOID = 2.88132 au   T_jup = 3.660

Simulation results ((note, Time 0 is JD 0 --> 4713 B.C.)

Kind Regards,
Alessandro Odasso