Binary asteroid
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A binary asteroid is a system of two asteroids orbiting their common center of mass, in analogy with binary stars. 243 Ida was the first binary asteroid to be identified when the Galileo spacecraft did a flyby in 1993. Since then numerous binary asteroids have been detected.
When both binary asteroids are similar in size, they are sometimes called "binary companions",[1] "double asteroids" or "doublet asteroids". A good example of a true binary companion is the 90 Antiope system. Binary asteroids with a small satellite, called a "moonlet", have been more commonly observed (see 22 Kalliope, 45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra, 243 Ida, 283 Emma, 379 Huenna, etc.)[1] They are also called high-size ratio binary asteroid systems.
Paired impact craters, such as the Clearwater Lakes in Canada, are possibly the result of when binary asteroids impact a planet.
Several theories have been posited to explain the formation of binary asteroid systems. Recent work suggests that most of them have a significant macro-porosity (a "rubble-pile" interior). The satellite orbiting around large main-belt asteroids such as 22 Kalliope, 45 Eugenia or 87 Sylvia could have formed by disruption of a parent body after impact or fission after an oblique impact. Transneptunian binary asteroids may have formed during the formation of the solar system by mutual capture or three-body interaction. Near-Earth asteroids which orbit in the inner part of our solar system may have split by tidal disruption after a close encounter with a terrestrial planet. A possible explanation for the relatively greater occurrence of binary asteroids near or inside of Earth's orbit was described in the journal Nature (10 June 2008): this theory states that when solar energy (see YORP effect) spins a “rubble pile” asteroid to a sufficiently fast rate, material is thrown from the asteroid’s equator. This process also exposes fresh material at the poles of the asteroid.[2][3]
[edit] References
- ^ a b "Satellites and Companions of Minor Planets". IAU / Minor Planet Center. 2009-09-17. http://www.cfa.harvard.edu/iau/minorsats.html. Retrieved 2009-10-14.
- ^ Walsh, Kevin J. (June 2008). "Rotational breakup as the origin of small binary asteroids.". Nature 454 (7201): 188–191. doi:. 10.1038/nature07078.
- ^ Study Puts Solar Spin on Asteroids, their Moons & Earth Impacts Newswise, Retrieved 14 July 2008.
[edit] See also
[edit] References
- ^ a b "Satellites and Companions of Minor Planets". IAU / Minor Planet Center. 2009-09-17. http://www.cfa.harvard.edu/iau/minorsats.html. Retrieved 2009-10-14.
- ^ Walsh, Kevin J. (June 2008). "Rotational breakup as the origin of small binary asteroids.". Nature 454 (7201): 188–191. doi:. 10.1038/nature07078.
- ^ Study Puts Solar Spin on Asteroids, their Moons & Earth Impacts Newswise, Retrieved 14 July 2008.
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