An asteroid pair, or (if more than one body) an asteroid cluster, are

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

s which at some point in the past had very small relative velocities, and are typically formed either by a collisional break-up of a parent body, or from binary asteroids which became gravitationally unbound and are now following similar but different orbits around the Sun. A possible example of a pair are the Trojan asteroids

1583 Antilochus 1583 Antilochus is a large Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 19 September 1950, by Belgian astronomer Sylvain Arend at Uccle Observatory in Belgium, and later named after the hero Antilochus fr ...

and

3801 Thrasymedes 3801 Thrasymedes is a mid-sized Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 6 November 1985, by astronomers with the Spacewatch survey at the Kitt Peak National Observatory in Arizona, United States. T ...

. The proposer of that pair, Andrea Milani, found five other potential asteroid clusters in the

Greek camp This is a list of Jupiter trojans that lie in the Greek camp, an elongated curved region around the leading Lagrangian point (), 60 ° ahead of Jupiter in its orbit. All the asteroids at Jupiter's point have names corresponding to participants ...

, clustered around the asteroids

1437 Diomedes 1437 Diomedes is a large Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 3 August 1937, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany. The dark D/P-type as ...

1647 Menelaus 1647 Menelaus is a mid-sized Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 23 June 1957 by American astronomer Seth Nicholson at the Palomar Observatory in California, and later named after the Spartan Kin ...

2456 Palamedes 2456 Palamedes is a large Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 30 January 1966, by astronomers at the Purple Mountain Observatory in Nanking, China. The assumed C-type asteroid has a rotation peri ...

2797 Teucer 2797 Teucer is a large Jupiter trojan from the Greek camp, approximately in diameter. It was discovered on 4 June 1981, by American astronomer Edward Bowell at the Anderson Mesa Station near Flagstaff, Arizona, in the United States. The dark D- ...

and 4035 Thestor. The youngest asteroid pairs discovered include the main-belt asteroids P/2016 J1-A/B (separated c. 2010) and / (separated c. 2003). The former pair is particularly remarkable for exhibiting comet-like activity due to water ice sublimation and rotational break-up.

References

{{reflist, refs= {{cite web , title = Asteroid pairs and clusters , work = Johnston's Archive , date = 29 April 2018 , author = Johnston, Wm. Robert , url = http://www.johnstonsarchive.net/astro/asteroidpairs.html , access-date = 30 June 2018 {{Cite journal , author = Milani, Andrea , date = October 1993 , title = The Trojan asteroid belt: Proper elements, stability, chaos and families , journal = Celestial Mechanics and Dynamical Astronomy , volume = 57 , issue = 1–2 , pages = 59–94 , issn = 0923-2958 , bibcode = 1993CeMDA..57...59M , doi = 10.1007/BF00692462 , s2cid = 189850747 {{cite journal , display-authors = etal , first1 = F. , last1 = Moreno , first2 = F. J. , last2 = Pozuelos , first3 = B. , last3 = Novaković , first4 = J. , last4 = Licandro , first5 = A. , last5 = Cabrera-Lavers , first6 = B. , last6 = Bolin , title = The Splitting of Double-component Active Asteroid P/2016 J1 (PANSTARRS) , url = http://www2.ess.ucla.edu/~jewitt/papers/2017/HJD17.pdf , journal = The Astrophysical Journal Letters , date = March 2017 , volume = 837 , issue = 1 , id = L3 , pages = 6 , doi-access = free , doi = 10.3847/2041-8213/aa6036 , arxiv = 1702.03665 , bibcode = 2017ApJ...837L...3M {{cite journal , first1 = D. , last1 = Vokrouhlický , first2 = P. , last2 = Fatka , first3 = M. , last3 = Micheli , first4 = P. , last4 = Pravec , first5 = E. J. , last5 = Christensen , title = Extremely young asteroid pair (458271) 2010 UM26 and 2010 RN221 , url = https://astro.troja.mff.cuni.cz/davok/papers/young_pair_AA2022.pdf , journal = Astronomy & Astrophysics , date = August 2022 , volume = 664 , id = L17 , pages = 6 , doi-access = free , doi = 10.1051/0004-6361/202244589 , arxiv = 2208.06207 , bibcode = 2022A&A...664L..17V Asteroid groups and families Asteroids