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A survey of Karin cluster asteroids with the Spitzer Space Telescope

Harris, A.W. und Mueller, M. und Lisse, C.M. und Cheng, A.F. (2008) A survey of Karin cluster asteroids with the Spitzer Space Telescope. Icarus: International Journal of Solar System Studies, 199 (1), Seiten 86-96. Academic Press. DOI: 10.1016/j.icarus.2008.09.004. ISSN 0019-1035.

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The Karin cluster is one of the youngest known families of main-belt asteroids, dating back to a collisional event only 5.8 ± 0.2 Myr ago. Using the Spitzer Space Telescope we have photometrically sampled the thermal continua (3.5–22 μm) of 17 Karin cluster asteroids of different sizes, down to the smallest members discovered so far, in order to make the first direct measurements of their sizes and albedos and study the physical properties of their surfaces. Our targets are also amongst the smallest mainbelt asteroids observed to date in the mid-infrared. The derived diameters range from 17.3 km for 832 Karin to 1.5 km for 75176, with typical uncertainties of 10%. The mean albedo is pv = 0.215 ± 0.015, compared to 0.20 ± 0.07 for 832 Karin itself (for H = 11.2 ± 0.3), consistent with the view that the Karin asteroids are closely related physically as well as dynamically. The albedo distribution (pv = 0.12 - 0.32) is consistent with the range associated with S-type asteroids but the variation from one object to another appears to be significant. Contrary to the case for near-Earth asteroids, our data show no evidence of an albedo dependence on size. However, the mean albedo is lower than expected for young, fresh “S-type” surfaces, suggesting that space weathering can darken main-belt asteroid surfaces on very short timescales. Our data are also suggestive of a connection between surface roughness and albedo, which may reflect rejuvenation of weathered surfaces by impact gardening. While the available data allow only estimates of lower limits for thermal inertia, we find no evidence for the relatively high values of thermal inertia reported for some similarly sized near-Earth asteroids. Our results constitute the first observational confirmation of the legitimacy of assumptions made in recent modeling of the formation of the Karin cluster via a single catastrophic collision 5.8±0.2 Myr ago.

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Titel:A survey of Karin cluster asteroids with the Spitzer Space Telescope
AutorenInstitution oder E-Mail-Adresse der Autoren
Lisse, C.M.Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, Maryland, USA
Cheng, A.F.Planetary Exploration Group, Space Department, Johns Hopkins University Applied Physics Laboratory, Maryland, USA
Datum:26 September 2008
Erschienen in:Icarus: International Journal of Solar System Studies
Referierte Publikation:Ja
In ISI Web of Science:Ja
DOI :10.1016/j.icarus.2008.09.004
Seitenbereich:Seiten 86-96
HerausgeberInstitution und/oder E-Mail-Adresse der Herausgeber
American Astronomical Society Division for Planetary Sciences, NICHT SPEZIFIZIERT
Verlag:Academic Press
Stichwörter:Asteroids, Infrared observations, Photometry, Spectrophotometry
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W EW - Erforschung des Weltraums
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W EW - Erforschung des Weltraums
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Asteroiden und Kometen (alt)
Standort: Berlin-Adlershof
Institute & Einrichtungen:Institut für Planetenforschung > Asteroiden und Kometen
Hinterlegt von: Prof. Alan Harris
Hinterlegt am:25 Nov 2008
Letzte Änderung:14 Jan 2010 23:57

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