2023 SP50 and 152737 (1998 WF28)

 Backward simulation

Mercury6 package by 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. 

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

) Important integration parameters:

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

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

 start time (days)=  2460106.5

) stop time (days) = 102458000.5

 stop time (days) = -1e8

 output interval (days) = 100

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Result

2015 TB430 and 1997 YF7

 Interesting couple.

Simulation based on nominal orbital parameters 

Mercury6 software

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

) Important integration parameters:

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

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

 start time (days)=  2460106.5

) stop time (days) = 102458000.5

 stop time (days) = -1e8

 output interval (days) = 100

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Simulation result

2015 BN494 and 2008 BY42

 Backward integration with Mercury6 software, integrator Bulirsch-Stoer, output every 100 days

2015 HB287 and 434936

Peter VanWylen noticed that these two asteroids stay very close to each other in the sky for many decades. He wondered whether they have  a common (recent) origin or it is a coincidence.

I run a Mercury6 simulation (output every 1 days) based on nominal parameters, while this is not a proof I think that the idea of a common origin should not be disregarded.

405222 (2003 RV20) and 2010 TH35

 Interesting couple, common origin?

100499 (1996 XP) and 2014 OT426

 Backward integration with Mercury6 based on nominal orbital parameters:

)---------------------------------------------------------------------
) Important integration parameters:
)---------------------------------------------------------------------
 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS
 start time (days)= 2459671.5
) stop time (days) = 102458000.5
 stop time (days) = -1d8
 output interval (days) = 100
 timestep (days) = 0.05
 accuracy parameter=1.d-12

Result

 P.S.

Following a comment from Afrien Coffinet (what happened at about year -15000 ?), I plotted the orbital parameters of the asteroids that are almost overlapped, at least at the scale of the graphics.

Around that date: 

• eccentricity reached the minimum value as confirmed by q and Q, 
• inclination reached the minimum value, 
• the argument of perihelium had a "disturbance" (encounter with a big planet? - not clear)
  
• the ascending node reached the maximum vaue)
  

 

 

Amors: (2019 QR6) and (2019 PR2)

On October 06th, 2019 I post a message on MPML list wondering about the nature of these two objects.

In fact that I was unable to link their orbits with Find_Orb. 

The message  was almost immediately answered by Bill Gray that already noticed the orbit similarity as you see in his answer.

For what is's worth, I tried a simulation going back just a few centuries.

I used the Mercury6 simulator (Bulirsch-Stoer algorithm, output every 100 days) to integrate the orbit of 100 clones for every Amor.

package by 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.

[ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Close-Approach Data ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB Reference: JPL 6 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .7978288096308341 0.00032564 a 5.77647017220784 0.0096039 au q 1.16783585084724 6.0685e-05 au i 10.97219839923067 0.0022769 deg node 349.0031380596452 0.0032242 deg peri 57.11459122817678 0.0037867 deg M 347.1017843073122 0.032425 deg tp 2458782.185121653621 (2019-Oct-25.68512165) 0.0037127 TDB period 5070.983875109436 13.88 12.646 0.03462 d yr n .07099214055225742 0.00017705 deg/d Q 10.38510449356844 0.017266 au

Orbit Determination Parameters    # obs. used (total)      55      data-arc span      37 days      first obs. used      2019-08-30      last obs. used      2019-10-06      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      6      norm. resid. RMS      .23771      source      ORB      producer      Otto Matic      solution date      2019-Oct-06 05:59:04   Additional Information  Earth MOID = .236027 au   Jupiter MOID = .430677 au   T_jup = 2.148

(2019 QR6)

Classification: Amor [NEO]          SPK-ID: 3843716

[ Ephemeris | Orbit Diagram | Orbital Elements | Mission Design | Physical Parameters | Close-Approach Data ]

[ show orbit diagram ]

Orbital Elements at Epoch 2458600.5 (2019-Apr-27.0) TDB Reference: JPL 13 (heliocentric ecliptic J2000)  Element Value Uncertainty (1-sigma)   Units  e .7976395056810581 7.5679e-05 a 5.771314015088342 0.0022317 au q 1.167885956963114 1.4922e-05 au i 10.98927716153723 0.0004847 deg node 349.0377844945419 0.00064504 deg peri 57.08297761694006 0.0010614 deg M 347.0982101299367 0.0075621 deg tp 2458781.992192675281 (2019-Oct-25.49219268) 0.0011319 TDB period 5064.195745018806 13.87 2.9374 0.008042 d yr n .0710872995685642 4.1233e-05 deg/d Q 10.37474207321357 0.0040118 au

Orbit Determination Parameters    # obs. used (total)      79      data-arc span      56 days      first obs. used      2019-08-10      last obs. used      2019-10-05      planetary ephem.      DE431      SB-pert. ephem.      SB431-N16      condition code      5      norm. resid. RMS      .47936      source      ORB      producer      Otto Matic      solution date      2019-Oct-06 05:59:04   Additional Information  Earth MOID = .236151 au   Jupiter MOID = .430922 au   T_jup = 2.149

(2019 PR2)

Classification: Amor [NEO]          SPK-ID: 3843547

I generated the clones trying to achieve the same orbital values as above.
This is what I got:

2019 QR6 

	Clones			Target
	mean	sd		mean	sd
q	1.16782936	6.072e-05		1.16783585	6.068e-05
e	0.7977961	0.00032594		0.79782881	0.00032564
i	10.97196669	0.00227869		10.9721984	0.0022769
peri	57.11505214	0.00378487		57.11459123	0.0037867
node	349.00281358	0.00322763		349.00313806	0.0032242
tp	2458782.18556559	0.00370968		2458782.18512165	0.0037127

2019 PR2

	Clones			Target
	mean	sd		mean	sd
q	1.16788572	1.491e-05		1.16788596	1.492e-05
e	0.79763725	7.562e-05		0.79763951	7.568e-05
i	10.98925764	0.00048534		10.98927716	0.0004847
peri	57.08297444	0.00106018		57.08297762	0.0010614
node	349.03776263	0.00064461		349.03778449	0.00064504
tp	2458781.99219263	0.00113238		2458781.99219268	0.0011319

I analyzed the 100*100 pairs, looking for pairs being very near with low relative velocity.

The best couple that I found behaved like this:

Apparently, somewhere around  year 1950 these two asteroids were at 2500 km with a relative velocity abot 10 m/s.

Does this make any sense?

Kind Regards
Alessandro Odasso

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