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

Potential Asteroid Pairs

This is a list of potential asteroid pairs (asteroid1 - asteroid2).

Asteroid1 and Asteroid2 have been very close in the past: whether this happened by chance or not needs to be confirmed. In fact, what you see here is just the result of a simulation made with Mercury software.

I am aware that any simulation result must be taken with caution. Besides any trivial error that I might have done, one must be aware that the simulation itself had these characteristics:

• no attempt to take into account Ceres, Pallas and Vesta
• no attempt to take into account non gravitational forces
• use of hybrid simplectic algorithm that is fast but maybe a little less precise than other algorithms

Once said this, if you look at the above list, you can get more details.
Open the embedded PDF in full screen mode, you will be able to click and follow the hyperlinks.

The hyperlink in column "Asteroid1_Asteroid2_Distance" will open a page  showing how the distance between the two asteroids varied in the past.

The hyperlink associated to the asteroid names will open a page of the AstDys system where you will find useful details that may help to put things in context.

For example, I already listed what I think is a useful information provided by AstDys , i.e.whether it is possible or not to identify a parent body for the family of the two asteroids of the pair and which are the nearest family members.

In some cases, the AstDys service is unable to identify a parent body for the asteroid pair:  it is not clear to me if this happens because the pair is really isolated or because it has not yet been associated to a family.
The fact that no parent body is identified does not  necessarily mean that the asteroid pair is not interesting and I guess that the opposite is also true: finding a parent body does not prove that the two asteroids are a divorced pair.

Let's look at the most important parent bodies listed above counting them.
This is the result :

Parent Body	Total
-	28
(158) Koronis	26
(135) Hertha	5
(4) Vesta	5
(1338) Duponta	3
(2076) Levin	2
(15) Eunomia	1
(1547) Nele	1
(16286) 4057P-L	1
(170) Maria	1
(20) Massalia	1
(606) Brangane	1
(668) Dora	1
(93) Minerva	1

In conclusion, about 1/3 of the cases belong to the (158) Koronis family, another 1/3 of the cases can not be related to known families, the last 1/3 is spread in other families.

Inside the Koronis family, the asteroid that more often appear to be related to the asteroid pairs are:

(11728) Einer

(2226) Cunitza (158) Koronis Kind Regards, Alessandro Odasso

Comet 169P and P/2003 T12

Comet 169P and P/2003 T12

The comets in the past: see point (3) of this message sent to MPML group

More details about 169P and P/2003 T12 in the past