Kirkwood gap
Encyclopedia : K : KI : KIR : Kirkwood gap
Kirkwood gaps are gaps or dips in the distribution of main belt asteroids with semi-major axis (or equivalently their orbital period), as seen in the [histogram below]. They correspond to the location of orbital resonances with Jupiter.
For example, there are very few asteroids with semimajor axis near 2.50 AU, period 3.95 years, which is one-third of the orbital period of Jupiter (hence, called the 1:3 orbital resonance). Other orbital resonances correspond to orbital periods whose lengths are simple fractions of Jupiter's. The weaker resonances lead only to a depletion of asteroids, while spikes in the histogram are often due to the presence of a prominent asteroid family.
The gaps were first noticed in 1857 by Daniel Kirkwood, who also correctly explained their origin in the orbital resonances with Jupiter.
More recently, a relatively small number of asteroids has been found to possess high eccentricity orbits which do lie within the Kirkwood gaps. Examples include the Alinda family and the Griqua family. These orbits slowly increase their eccentricity on a timescale of tens of millions of years, and will eventually break out of the resonance due to close encounters with a major planet.
The Kirkwood gaps are located at mean orbital radii of:
- 1.9 AU (2:9 resonance)
- 2.06 AU (1:4 resonance)
- 2.25 AU (2:7 resonance)
- 2.5 AU (1:3 resonance), home to the Alinda family of asteroids
- 2.706 AU (3:8 resonance)
- 2.82 AU (2:5 resonance)
- 2.95 AU (3:7 resonance)
- 3.27 AU (1:2 resonance), home to the Griqua family of asteroids
- 3.7 AU (3:5 resonance)
See also
External links
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.