Volume 418, Number 1, April IV 2004
|Page(s)||347 - 356|
|Section||Planets and planetary systems|
|Published online||02 April 2004|
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany e-mail: email@example.com
2 Katholieke Universiteit Leuven, Instituut voor Sterrenkunde Celestijnenlaan 200B, 3001 Leuven, Belgium e-mail: firstname.lastname@example.org
Corresponding author: T. G. Müller, email@example.com
Accepted: 15 January 2004
We investigated the physical and thermal properties of 65 Cybele, one of the largest main-belt asteroids. Based on published and recently obtained thermal infrared observations, including ISO measurements, we derived through thermophysical modelling (TPM) a size of km (±4%) and an geometric visible albedo of . Our model of a regolith covered surface with low thermal inertia and “default" roughness describes the wavelengths and phase angle dependent thermal effects very well. Before/after opposition effect and beaming behaviour can be explained in that way. We found a constant emissivity of 0.9 at wavelengths up to about 100 μm and lower values towards the submillimetre range, indicating a grain size distribution dominated by 200 μm particle sizes. The spectroscopic analysis revealed an emissivity increase between 8.0 and 9.5 μm. We compared this emissivity behaviour with the Christiansen features of carbonaceous chondrite meteorites, but a conclusive identification was not possible. A comparison between the Standard Thermal Model (STM) and the applied TPM clearly demonstrates the limitations and problems of the STM for the analysis of multi-epoch and -wavelengths observations. While the TPM produced a unique diameter/albedo solution, the calculated STM values varied by ±30% and showed clear trends with wavelength and phase angle. 65 Cybele can be considered as a nice textbook case for the thermophysical analysis of combined optical and thermal infrared observations.
Key words: minor planets, asteroids / radiation mechanisms: thermal / infrared: solar system
© ESO, 2004
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.