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Sunday, September 22, 2019

2018 TM7 - a member of Datura cluster?

According to https://astro.troja.mff.cuni.cz/davok/papers/clusters_Icarus2018.pdf , asteroid 2016 TW15 is a probable member of the Datura cluster.

Asteroids 2018 TM7 and 2016 TW15 have similar orbital parameters, so one can wonder whether they are related as well.

Using a similar approach as described in the previous post, I got the following preliminary results.

Horizons Web-Interface
Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB
Reference: JPL 2 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .2073298995769193 3.8379e-06
a 2.235046338287878 2.301e-05 au
q 1.771654405420891 1.2968e-05 au
i 5.990117205423358 4.7269e-05 deg
node 97.82547015326649 0.00054111 deg
peri 259.4145809193611 0.0032119 deg
M 68.99123090087689 0.0020078 deg
tp 2458366.605711434710
(2018-Sep-05.10571143)
0.0058977 TDB
period 1220.473135266737
3.34
0.018847
5.16e-05
d
yr
n .2949675741296193 4.5551e-06 deg/d
Q 2.698438271154865 2.7781e-05 au
Orbit Determination Parameters
   # obs. used (total)      29  
   data-arc span      79 days  
   first obs. used      2018-08-21  
   last obs. used      2018-11-08  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      4  
   norm. resid. RMS      .44663  
   source      ORB  
   producer      Otto Matic  
   solution date      2019-Feb-18 10:04:49  

Additional Information
 Earth MOID = .778475 au 
 Jupiter MOID = 2.75817 au 
 T_jup = 3.603 
(2018 TM7)
Classification: Main-belt Asteroid          SPK-ID: 3835925



Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB
Reference: JPL 3 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .2074483215033754 6.276e-05
a 2.235611802114912 0.00019509 au
q 1.771837886233037 0.00014694 au
i 5.991604667652219 0.00042723 deg
node 97.1620742657492 0.0056502 deg
peri 260.1246967378749 0.051079 deg
M 285.0627975716027 0.045951 deg
tp 2458854.648758455576
(2020-Jan-06.14875846)
0.18292 TDB
period 1220.936331742965
3.34
0.15982
0.0004376
d
yr
n .2948556698989184 3.8596e-05 deg/d
Q 2.699385717996787 0.00023556 au
Orbit Determination Parameters
   # obs. used (total)      30  
   data-arc span      59 days  
   first obs. used      2016-08-12  
   last obs. used      2016-10-10  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      5  
   norm. resid. RMS      .2906  
   source      ORB  
   producer      Otto Matic  
   solution date      2017-Oct-09 14:42:03  

Additional Information
 Earth MOID = .778751 au 
 Jupiter MOID = 2.75758 au 
 T_jup = 3.603 
(2016 TW15)
Classification: Main-belt Asteroid          SPK-ID: 3760646

Clone generation
100 clones were generated for both asteroids, trying to achieve the same orbital parameters and uncertainty as above:

summary_2018+TM7

Clones Target
mean sd mean sd
q 1.77165498 1.294e-05 1.77165441 1.297e-05
e 0.20732936 3.84e-06 0.2073299 3.84e-06
i 5.99011663 4.722e-05 5.99011721 4.727e-05
peri 259.41529374 0.00321844 259.41458092 0.0032119
node 97.82537494 0.00053868 97.82547015 0.00054111
tp 2458366.60704583 0.00589821 2458366.60571143 0.0058977

summary_2016+TW15

Clones Target
mean sd mean sd
q 1.77183536 0.00014688 1.77183789 0.00014694
e 0.20745945 6.28e-05 0.20744832 6.276e-05
i 5.99162255 0.00042743 5.99160467 0.00042723
peri 260.11780583 0.05113712 260.12469674 0.051079
node 97.16314414 0.00565394 97.16207427 0.0056502
tp 2458854.62514345 0.18310294 2458854.64875846 0.18292



Simulation results
I analyzed the 10000 clones pairs searching for the time when every pair had the minimum distance (registering the relative velocity as well).
Of course every pair is different and we can get a feel of variations looking at the following plots:




Best Clone Couple
About 30% of the clone pairs reached a minimum distance below 1 Lunar Distance.
The best one made far better as you can see here:



Kind Regards,
Alessandro Odasso

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