A survey of Karin cluster asteroids with the Spitzer Space Telescope
Harris, A.W. and Mueller, M. and Lisse, C.M. and Cheng, A.F. (2008) A survey of Karin cluster asteroids with the Spitzer Space Telescope. Icarus: International Journal of Solar System Studies, 199 (1), pp. 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.
|Additional Information:||bisher nur Online-Veröffentlichung|
|Title:||A survey of Karin cluster asteroids with the Spitzer Space Telescope|
|Date:||26 September 2008|
|Journal or Publication Title:||Icarus: International Journal of Solar System Studies|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 86-96|
|Keywords:||Asteroids, Infrared observations, Photometry, Spectrophotometry|
|HGF - Research field:||Aeronautics, Space and Transport|
|HGF - Program:||Space|
|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)|
|Institutes and Institutions:||Institute of Planetary Research > Asteroids and Comets|
|Deposited By:||Prof. Alan Harris|
|Deposited On:||25 Nov 2008|
|Last Modified:||14 Jan 2010 23:57|
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