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21 Lutetia and other M-types: Their sizes, albedos, and thermal properties from new IRTF measurements

Mueller, Michael and Harris, Alan W. and Delbo, Marco and MIRSI-team, (2005) 21 Lutetia and other M-types: Their sizes, albedos, and thermal properties from new IRTF measurements. In: Bulletin of the American Astronomical Society, 37, p. 627. DPS meeting 2005, 2005-09-04 - 2005-09-09, Cambridge (GB).

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Official URL: http://www.aas.org/publications/baas/v37n3/dps2005/486.htm


The M-type taxonomic group, introduced by Tholen (1989), contains asteroids with generally featureless spectra and IRAS albedos of around 0.2. M-type asteroids were originally believed to have a metallic surface composition. However, it now seems that other types of surface composition may also give rise to M-type spectra (e.g. Rivkin et al., 2000). One of the Rosetta fly-by targets, M-type asteroid 21 Lutetia, was recently found by several authors to display spectral features indicative of a more primitive surface composition, which is usually associated with a C-type classification and a low albedo incompatible with the IRAS albedo for Lutetia. We report results from new thermal-infrared observations of Lutetia and other M-type asteroids performed at the NASA IRTF. The radiometric sizes and albedos of the targets have been determined and information on thermal properties such as thermal inertia has been derived from the apparent color temperatures of their thermal continua. One might expect metallic surfaces to have higher thermal conductivities and therefore to be associated with higher values of thermal inertia. The diameter and albedo derived for Lutetia are 98.3 +/- 5.9 km and pv = 0.208 +/- 0.025, in excellent agreement with the IRAS values. A C-type albedo (pv up to 0.1) is therefore ruled out but our results are not indicative of an unusually high thermal inertia. We also report on the analysis of observations of the M-type asteroids (129) Antigone and (785) Zwetana, both of which appear to have patches of very high and low radar albedo (M. Shepard, private communication) consistent with (but not restricted to) a metal and non-metal surface composition, respectively.

Item URL in elib:https://elib.dlr.de/20820/
Document Type:Conference or Workshop Item (Speech)
Title:21 Lutetia and other M-types: Their sizes, albedos, and thermal properties from new IRTF measurements
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Delbo, MarcoINAF - Astronomical Observatory of TurinUNSPECIFIEDUNSPECIFIED
Journal or Publication Title:Bulletin of the American Astronomical Society
Refereed publication:No
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Page Range:p. 627
Event Title:DPS meeting 2005
Event Location:Cambridge (GB)
Event Type:international Conference
Event Start Date:4 September 2005
Event End Date:9 September 2005
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EW - Erforschung des Weltraums
DLR - Research area:Space
DLR - Program:W EW - Erforschung des Weltraums
DLR - Research theme (Project):W - Vorhaben Asteroiden und Kometen (old)
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Asteroids and Comets
Deposited By: Müller, Michael
Deposited On:01 Mar 2006
Last Modified:24 Apr 2024 19:02

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