EDP Sciences
Free access
Volume 415, Number 2, February IV 2004
Page(s) 771 - 775
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20035603

A&A 415, 771-775 (2004)
DOI: 10.1051/0004-6361:20035603

Size estimates of some optically bright KBOs

W. J. Altenhoff, F. Bertoldi and K. M. Menten

Max-Planck-Institut für Radioastronomie (MPIfR), Auf dem Hügel 69, 53121 Bonn, Germany
    e-mail: waltenhoff@mpifr-bonn.mpg.de
(Received 30 October 2003 / Accepted 10 November 2003)

Seven recently detected optically "bright" Kuiper-Belt-Objects (KBOs) were observed at 250 GHz using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30 m telescope. Only the optical binary KBO (47 171) 1999 TC36 was detected, whose components differ optically by $ \Delta m \approx 2$ mag. Assuming that the derived mean geometric albedo of  p = 0.05 is identical for both, the component diameters become 566 and 225 km. For the other six objects upper limits to their sizes and lower limits for their albedos were obtained. The geometric albedo, p, for (28978) Ixion is surprisingly large, $\ge$0.15. For a consistent comparison all published radio photometric data of KBOs and Centaurs were analyzed again: the average geometric albedo is found to be  $\approx$ 0.08.

Key words: minor planets -- radio continuum: solar system

Offprint request: W. J. Altenhoff, waltenhoff@mpifr-bonn.mpg.de

© ESO 2004