35448 (2018 TM7) and (2018 VR79) and (2015 PR301) - Datura cluster

Besides 2018 TM7 that I mentioned a few days ago, I wonder whether (2018 VR79) and (2015 PR301)  belong to the Datura cluster as well

                                 a            e              i           om           w  

       (2018 TM7)   2.235046 0.2073299 5.990117 97.82547 -100.5854

       (2018 VR79)  2.235106 0.2074233 5.990621 97.33788  -99.9308

       (2015 PR301) 2.234921 0.2072752 5.986435 98.29115 -101.3660

In fact, their  orbital parameters are very similar to those of these two recognized members of the Datura cluster:

                                     a         e                  i       om             w  

       (2016 TW15)     2.235612 0.2074483 5.991605 97.16207  -99.8753

433382 (2013 ST71)  2.234977 0.2081608 5.984741 97.94635 -101.1312

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

2013 ST71 - A member of the Datura cluster ?

These 7 asteroids are already recognized as belonging to the Datura cluster:

• (1270) Datura
• (60151) 1999UZ6 
• (89309) 2001VN36 
• (90265) 2003CL5 
• (203370) 2001 WY35
• (215619) 2003 SQ168
• 2003 UD112

Is asteroid 2013 ST71  a member of the Datura cluster ?

At first glance, I would say yes: the orbit of 2013 ST71 is very similar to the orbit of (1270) Datura, but it is not clear to me if this happens by chance or not .


Let's look at Horizons Web -

(1270) Datura

Element	Value	Uncertainty (1-sigma)	Units
e	.207362426961996	6.897e-08
a	2.23509416609344	7.619e-09	AU
q	1.771619615323705	1.539e-07	AU
i	5.988581620229616	5.1796e-06	deg
node	97.85012324839816	6.7015e-05	deg
peri	258.8674632296458	6.7965e-05	deg
M	69.4456617884065	1.2739e-05	deg
tp	2456565.057541251396 (2013-Sep-29.55754125)	4.2797e-05	JED
period	1220.512310873357 3.34	6.2407e-06 1.709e-08	d yr
n	.294958106356499	1.5082e-09	deg/d
Q	2.698568716863174	9.1989e-09	AU

2013 ST71

Element Value Uncertainty (1-sigma)   Units  e .2072926241711973 2.4439e-07 a 2.235332639213504 3.0253e-08 AU q 1.771964670535408 5.4988e-07 AU i 5.98688637443826 1.0741e-05 deg node 97.99751181500383 0.00026181 deg peri 258.8943816441401 0.00026916 deg M 78.4852036132318 4.0622e-05 deg tp 2456534.368087665562 (2013-Aug-29.86808767) 0.00013895 JED period 1220.707649718649 3.34 2.4781e-05 6.785e-08 d yr n .2949109068686294 5.9869e-09 deg/d Q 2.698700607891598 3.6524e-08 AU

A few month ago, we also mentioned that another asteroid (338309) 2002 VR17 might be a member of the same cluster - if these findings are confirmed, the Datura cluster would have at least 9 recognized members.

At the end of this embedded PDF (a list of potential asteroid pairs to be confirmed / rejected), there is an entry for 2013 ST71:



Click on asteroid names to get more details from the AstDyS service.
Click on Asteroid1_Asteroid2 distance to see a graph showing how the distance between the two asteroids varied in the past according to a simulation performed with Mercury simulator.

Kind Regards,
Alessandro Odasso