Pairs of Asteroids Probably of a Common Origin
Abstract
We report the first observational evidence for pairs of main-belt asteroids with bodies in each pair having nearly identical orbits. The existence of ~60 pairs identified here cannot be reconciled with random fluctuations of the asteroid orbit density and rather suggests a common origin of the paired objects. We propose that the identified pairs formed by (i) collisional disruptions of km-sized and larger parent asteroids, (ii) Yarkovsky-O'Keefe-Radzievski-Paddack (YORP)-induced spin-up and rotational fission of fast-rotating objects, and/or (iii) splitting of unstable asteroid binaries. In case (i), the pairs would be parts of compact collisional families with many km- and sub-km-size members that should be found by future asteroid surveys. Our dynamical analysis suggests that most identified pairs formed within the past lsim1 Myr, in several cases even much more recently. For example, paired asteroids (6070) Rheinland and (54827) 2001 NQ8 probably separated from their common ancestor only 16.5-19 kyr ago. Given their putatively very recent formation, the identified objects are prime candidates for astronomical observations.
The title paraphrases that of Hirayama's 1918 paper "Groups of asteroids probably of a common origin," where the first evidence was given for groups of asteroid fragments produced by disruptive collisions.- Publication:
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The Astronomical Journal
- Pub Date:
- July 2008
- DOI:
- 10.1088/0004-6256/136/1/280
- Bibcode:
- 2008AJ....136..280V
- Keywords:
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- minor planets;
- asteroids