Asteroid families

Asteroid families

Fig. 12.5 . The orbital parameters of many asteroids are very similar, as shown in this diagram of orbital inclination (vertical axis) plotted as a function of orbital distance from the Sun (horizontal axis). Three families with common orbital elements are the Koronis, Eos and Themis families. The Flora family is sometimes subdivided into several separate ones. The Hungaria and Phocaea group of asteroids at high inclinations are separated from the main belt by secular resonance with Jupiter, that clears asteroids out of certain locations, and they are not true families. The Kirkwood gaps, also cleared by resonance, are noticeable by vertical white spaces; the one at 2.5 AU corresponds to an orbital period of 4 years and the 3:1 resonance. Another sharp break is present at 3.3 AU, corresponding to a period of 6 years and the 2:1 resonance. [Adapted from Charles T. Kowal’s Asteroids (New York: John Wiley 1996).]

Copyright 2010, Professor Kenneth R. Lang, Tufts University