EDP Sciences
Free access
Volume 441, Number 1, October I 2005
Page(s) L5 - L7
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200500172

A&A 441, L5-L7 (2005)
DOI: 10.1051/0004-6361:200500172


On the density of EKOs and related objects

W. J. Altenhoff1, F. Bertoldi1, 2, K. M. Menten1 and C. Thum3

1  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
    e-mail: author@mpifr-bonn.mpg.de
2  Radioastronomisches Institut der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
    e-mail: bertoldi@astro.uni-bonn.de
3  IRAM, Domaine Universitaire de Grenoble, 300 rue de la piscine, 38406 St. Martin d'Hères, France
    e-mail: thum@iram.fr

(Received 25 May 2005 / Accepted 11 August 2005 )

Recently published mass determinations of EKO binaries, combined with photometric size determinations, allow to derive a mean density of the distant minor planets of $\approx$0.2 g cm-3. This agrees well with the nuclear density of 1P/Halley of 0.26 g cm-3, determined in the Giotto mission, and it suggests that these low density objects are essentially undifferentiated planetesimals.

Key words: minor planets: general -- comets: individual: Halley

© ESO 2005