Title: ASTROBJ65 Cybele/ASTROBJ in the thermal infrared: Multiple observations and thermophysical analysis
Authors: Müller, TG ×
Blommaert, Joris #
Issue Date: 2004
Series Title: Astronomy and Astrophysics vol:418 pages:347-356
Abstract: We investigated the physical and thermal properties of 65 Cybele, one of the largest main-belt asteroids. Based oil published and recently obtained thermal infrared observations, including ISO measurements, we derived through thermophysical modelling (TPM) a size of 302 x 290 x 232 kin (+/-4%) and an geometric visible albedo of 0.050 +/- 0.005. 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 pm and lower values towards the submillimetre range, indicating a grain size distribution dominated by 200 mum particle sizes. The spectroscopic analysis revealed an emissivity increase between 8.0 and 9.5 mum. 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.
ISSN: 0004-6361
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Institute of Astronomy
× corresponding author
# (joint) last author

Files in This Item:

There are no files associated with this item.

Request a copy


All items in Lirias are protected by copyright, with all rights reserved.

© Web of science