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Radar and infrared observations of binary near-Earth Asteroid 2002 CE26 |
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| Authors: | Michael K Shepard Jean-Luc Margot Michael C Nolan Benjamin Estes Eric L Volquardsen Lance AM Benner Steven J Ostro |
| Institution: | a Department of Geography and Geosciences, Bloomsburg University of Pennsylvania, 400 E. Second St., Bloomsburg, PA 17815, USA b Department of Astronomy, Cornell University, 304 Space Sciences Building, Ithaca, NY 14853, USA c University of Maine at Farmington, Preble Hall, 173 High Street, Farmington, ME 04938, USA d Arecibo Observatory, National Astronomy and Ionosphere Center, PR 00612, USA e Department of Physics and Engineering Technology, Bloomsburg University, Bloomsburg, PA 17815, USA f University of Hawaii, Hilo, HI 96720, USA g Institute for Astronomy, 640 North A'ohoku Place, Hilo, HI 96720, USA h Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723, USA i Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA j California Institute of Technology, Pasadena, CA 91109, USA |
| Abstract: | We observed near-Earth Asteroid (NEA) 2002 CE26 in August and September 2004 using the Arecibo S-band (2380-MHz, 12.6-cm) radar and NASA's Infrared Telescope Facility (IRTF). Shape models obtained based on inversion of our delay-Doppler images show the asteroid to be 3.5±0.4 km in diameter and spheroidal; our corresponding nominal estimates of its visual and radar albedos are 0.07 and 0.24, respectively. Our IRTF spectrum shows the asteroid to be C-class with no evidence of hydration. Thermal models from the IRTF data provide a size and visual albedo consistent with the radar-derived estimate. We estimate the spin-pole to be within a few tens of degrees of λ=317°, β=−20°. Our radar observations reveal a secondary approximately 0.3 km in diameter, giving this binary one of the largest size differentials of any known NEA. The secondary is in a near-circular orbit with period 15.6±0.1 h and a semi-major axis of 4.7±0.2 km. Estimates of the binary orbital pole and secondary rotation rate are consistent with the secondary being in a spin-locked equatorial orbit. The orbit corresponds to a primary mass of M=1.95±0.25×1013 kg, leading to a primary bulk density of  , one of the lowest values yet measured for a main-belt or near-Earth asteroid. |
| Keywords: | Asteroids Asteroids composition Asteroids surfaces Radar observations |
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