TY - JOUR
T1 - A radar survey of M- and X-class asteroids
AU - Shepard, Michael K.
AU - Clark, Beth Ellen
AU - Nolan, Michael C.
AU - Howell, Ellen S.
AU - Magri, Christopher
AU - Giorgini, Jon D.
AU - Benner, Lance A.M.
AU - Ostro, Steven J.
AU - Harris, Alan W.
AU - Warner, Brian
AU - Pray, Donald
AU - Pravec, Petr
AU - Fauerbach, Michael
AU - Bennett, Thomas
AU - Klotz, Alain
AU - Behrend, Raoul
AU - Correia, Horacio
AU - Coloma, Josep
AU - Casulli, Silvano
AU - Rivkin, Andrew
N1 - Funding Information:
M.K.S. and B.E.C. gratefully acknowledge support from NSF Grants AST-0605903 and AST-0606704. C.M. was partially supported by NSF Grant AST-0205975. A.W.H. and B.D.W acknowledge support from NASA Grant NNG06GI32G and NSF Grant AST-0607505. P.P. was supported by the Grant Agency of the Czech Republic, Grant 205/05/0604. 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. We thank the technical staff at each observatory for help with observations. Some of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This material is based in part upon work supported by the National Aeronautics and Space Administration (NASA) under the Science Mission Directorate Research and Analysis Programs.
PY - 2008/5
Y1 - 2008/5
N2 - We observed ten M- and X-class main-belt asteroids with the Arecibo Observatory's S-band (12.6 cm) radar. The X-class asteroids were targeted based on their albedos or other properties which suggested they might be M-class. This work brings the total number of main-belt M-class asteroids observed with radar to 14. We find that three of these asteroids have rotation rates significantly different from what was previously reported. Based on their high radar albedo, we find that only four of the fourteen-16 Psyche, 216 Kleopatra, 758 Mancunia, and 785 Zwetana-are almost certainly metallic. 129 Antigone has a moderately high radar albedo and we suggest it may be a CH/CB/Bencubbinite parent body. Three other asteroids, 97 Klotho, 224 Oceana, and 796 Sarita have radar albedos significantly higher than the average main belt asteroid and we cannot rule out a significant metal content for them. Five of our target asteroids, 16 Psyche, 129 Antigone, 135 Hertha, 758 Mancunia, and 785 Zwetana, show variations in their radar albedo with rotation. We can rule out shape and composition in most cases, leaving variations in thickness, porosity, or surface roughness of the regolith to be the most likely causes. With the exception of 129 Antigone, we find no hydrated M-class asteroids (W-class; Rivkin, A.S., Howell, E.S., Lebofsky, L.A., Clark, B.E., Britt, D.T., 2000. Icarus 145, 351-368) to have high radar albedos.
AB - We observed ten M- and X-class main-belt asteroids with the Arecibo Observatory's S-band (12.6 cm) radar. The X-class asteroids were targeted based on their albedos or other properties which suggested they might be M-class. This work brings the total number of main-belt M-class asteroids observed with radar to 14. We find that three of these asteroids have rotation rates significantly different from what was previously reported. Based on their high radar albedo, we find that only four of the fourteen-16 Psyche, 216 Kleopatra, 758 Mancunia, and 785 Zwetana-are almost certainly metallic. 129 Antigone has a moderately high radar albedo and we suggest it may be a CH/CB/Bencubbinite parent body. Three other asteroids, 97 Klotho, 224 Oceana, and 796 Sarita have radar albedos significantly higher than the average main belt asteroid and we cannot rule out a significant metal content for them. Five of our target asteroids, 16 Psyche, 129 Antigone, 135 Hertha, 758 Mancunia, and 785 Zwetana, show variations in their radar albedo with rotation. We can rule out shape and composition in most cases, leaving variations in thickness, porosity, or surface roughness of the regolith to be the most likely causes. With the exception of 129 Antigone, we find no hydrated M-class asteroids (W-class; Rivkin, A.S., Howell, E.S., Lebofsky, L.A., Clark, B.E., Britt, D.T., 2000. Icarus 145, 351-368) to have high radar albedos.
KW - Asteroids
KW - Surfaces
KW - asteroids
KW - composition
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U2 - 10.1016/j.icarus.2007.11.032
DO - 10.1016/j.icarus.2007.11.032
M3 - Article
AN - SCOPUS:42049099354
SN - 0019-1035
VL - 195
SP - 184
EP - 205
JO - Icarus
JF - Icarus
IS - 1
ER -