The Pallas family of asteroids is a grouping of B-type asteroids at very high inclinations in the intermediate main belt (Cellino et al (2002)).

The namesake is 2 Pallas, an extremely large asteroid with a mean diameter of about 530 km. The remaining bodies are far smaller (the largest being 5222 Ioffe with an estimated diameter of 22 km), which indicates that this is probably a so-called cratering family composed of ejecta from impacts onto the parent body 2 Pallas.

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

! !! a_p !! e_p !! i_p''

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 ^*) is about

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

The family appears to be genuinely derived from impacts onto Pallas due to the preponderance of the otherwise rare B spectral type among its members.

The grouping was first noted by Kiyotsugu Hirayama in 1928, and later by Brouwer (1951), Kozai (1979), and Lemaitre&Morbidelli (1994).

References

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• A. Lemaitre & A. Morbidelli, Proper elements for highly inclined asteroidal orbits, Celestial Mechanics and Dynamical Astronomy, Vol. 60, pp. 29 (1994).
• Y. Kozai [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1979IAUS...81..231K&db_key=AST&data_type=HTML&format=&high=43ee033a4808372 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

Pallas asteroids | Asteroid groups and families