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Physical properties of near-Earth asteroid 2011 MD

Mommert, M. and Farnocchia, D. and Hora, J. L. and Chesley, S. R. and Trilling, D. E. and Chodas, P. W. and Mueller, M. and Harris, A. W. and Smith, H. A. and Fazio, G. G. (2014) Physical properties of near-Earth asteroid 2011 MD. The Astrophysical Journal Letters, 789 (1). L22. ISSN 1538-4357


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Publisher’s or external URL: http://dx.doi.org/10.1088/2041-8205/789/1/l22


We report on observations of near-Earth asteroid 2011 MD with the Spitzer Space Telescope. We have spent 19.9 hr of observing time with channel 2 (4.5 μm) of the Infrared Array Camera and detected the target within the 2σ positional uncertainty ellipse. Using an asteroid thermophysical model and a model of nongravitational forces acting upon the object, we constrain the physical properties of 2011 MD, based on the measured flux density and available astrometry data. We estimate 2011 MD to be (6) m in diameter with a geometric albedo of 0.3 (uncertainties are 1σ). We find the asteroid's most probable bulk density to be (1.1) g cm–3, which implies a total mass of (50-350) t and a macroporosity of ≥65%, assuming a material bulk density typical of non-primitive meteorite materials. A high degree of macroporosity suggests that 2011 MD is a rubble-pile asteroid, the rotation of which is more likely to be retrograde than prograde.

Item Type: Article
Publisher’s Statement: Copyright 2014. The American Astronomical Society.
ID number or DOI: 10.1088/2041-8205/789/1/L22
Keywords: fragments; infrared: planetary systems; minor planets, asteroids: individual (2011 MD); neowise; radiation pressure; spitzer-space-telescope; yarkovsky
Subjects: Q Science > QB Astronomy
Department/Unit: College of Engineering, Forestry, and Natural Science > Physics and Astronomy
Date Deposited: 28 Mar 2016 21:02
URI: http://openknowledge.nau.edu/id/eprint/1843

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