Pallas family

The Pallas or Palladian family of asteroids is a grouping of B-type asteroids at very high inclinations in the intermediate asteroid belt (Cellino et al. (2002)). It was first noted by Kiyotsugu Hirayama in 1928.

The namesake of the family is 2 Pallas, an extremely large asteroid with a mean diameter of about 550 km. The remaining bodies are far smaller; the largest is 5222 Ioffe with an estimated diameter of 22 km. This, along with the preponderance of the otherwise rare B spectral type among its members, indicates that this is likely a cratering family composed of ejecta from impacts on Pallas. Another suspected Palladian is 3200 Phaethon, the parent body of the Geminid meteor shower.

Location and structure of the Pallas family.

From the diagram, their proper orbital elements lie in the approximate ranges

	ap	ep	ip
min	2.71 AU	0.25	32°
max	2.79 AU	0.31	34°

At the present epoch, the range of osculating orbital elements of the members (by comparison to the MPCORB database [2]) is about

	a	e	i
min	2.71 AU	0.13	30°
max	2.79 AU	0.37	38°

References

• A. Lemaitre & A. Morbidelli, Proper elements for highly inclined asteroidal orbits, Celestial Mechanics and Dynamical Astronomy, Vol. 60, pp. 29 (1994).
• Y. Kozai Secular perturbations of asteroids and comets In: Dynamics of the solar system; Proceedings of the Symposium, Tokyo, Japan, May 23-26, 1978. Dordrecht, D. Reidel Publishing Co., 1979, p. 231-236; Discussion, p. 236, 237.
• A. Cellino et al. "Spectroscopic Properties of Asteroid Families", in Asteroids III, p. 633-643, University of Arizona Press (2002). (Table on page 636, in particular).
• MPCORB orbit database