TY - JOUR
T1 - A radar survey of main-belt asteroids
T2 - Arecibo observations of 55 objects during 1999-2003
AU - Magri, Christopher
AU - Nolan, Michael C.
AU - Ostro, Steven J.
AU - Giorgini, Jon D.
N1 - Funding Information:
We thank the Arecibo technical staff for its help with the observations, Ellen Howell for helpful discussions, and the two anonymous reviewers for their comments. C. Magri was partially supported by NSF Grant AST-0205975. The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation. Part of this research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). This material is based in part upon work supported by NASA under the Science Mission Directorate Research and Analysis Programs.
PY - 2007/1
Y1 - 2007/1
N2 - We report Arecibo observations of 55 main-belt asteroids (MBAs) during 1999-2003. Most of our targets had not been detected previously with radar, so these observations more than double the number of radar-detected MBAs. Our bandwidth estimates constrain our targets' pole directions in a manner that is geometrically distinct from optically derived constraints. We present detailed statistical analyses of the disk-integrated properties (radar albedo and circular polarization ratio) of the 84 MBAs observed with radar through March 2003; all of these observations are summarized in the online supplementary information. Certain conclusions reached in previous studies are strengthened: M asteroids have higher mean radar albedos and a wider range of albedos than do other MBAs, suggesting that both metal-rich and metal-poor M-class objects exist; and C- and S-class MBAs have indistinguishable radar albedo distributions, suggesting that most S-class objects are chondritic. Also in accord with earlier results, there is evidence that primitive asteroids from outside the C taxon (F, G, P, and D) are not as radar-bright as C and S objects, but a convincing statistical test must await larger sample sizes. In contrast with earlier work, we find S-class MBAs to have higher circular polarization ratios than other MBAs, indicating greater near-surface structural complexity at decimeter scales, due to different mineralogy (material strength or loss tangent), a different impactor population, or both.
AB - We report Arecibo observations of 55 main-belt asteroids (MBAs) during 1999-2003. Most of our targets had not been detected previously with radar, so these observations more than double the number of radar-detected MBAs. Our bandwidth estimates constrain our targets' pole directions in a manner that is geometrically distinct from optically derived constraints. We present detailed statistical analyses of the disk-integrated properties (radar albedo and circular polarization ratio) of the 84 MBAs observed with radar through March 2003; all of these observations are summarized in the online supplementary information. Certain conclusions reached in previous studies are strengthened: M asteroids have higher mean radar albedos and a wider range of albedos than do other MBAs, suggesting that both metal-rich and metal-poor M-class objects exist; and C- and S-class MBAs have indistinguishable radar albedo distributions, suggesting that most S-class objects are chondritic. Also in accord with earlier results, there is evidence that primitive asteroids from outside the C taxon (F, G, P, and D) are not as radar-bright as C and S objects, but a convincing statistical test must await larger sample sizes. In contrast with earlier work, we find S-class MBAs to have higher circular polarization ratios than other MBAs, indicating greater near-surface structural complexity at decimeter scales, due to different mineralogy (material strength or loss tangent), a different impactor population, or both.
KW - Asteroids
KW - Radar observations
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U2 - 10.1016/j.icarus.2006.08.018
DO - 10.1016/j.icarus.2006.08.018
M3 - Article
AN - SCOPUS:33845317622
VL - 186
SP - 126
EP - 151
JO - Icarus
JF - Icarus
SN - 0019-1035
IS - 1
ER -