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Multi-wavelength observations of Asteroid 2100 Ra-Shalom |
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| Authors: | Michael K Shepard Beth Ellen Clark Lance AM Benner Jon D Giorgini Kandy Jarvis Lucy F Lim James Bell Andrew Rivkin Daniel Scheeres |
| Institution: | a Department of Geography and Geosciences, Bloomsburg University of Pennsylvania, 400 E. Second St., Bloomsburg, PA 17815, USA b Ithaca College, 267 Ctr for Natural Sciences, Ithaca, NY 14850, USA c National Astronomy and Ionosphere Center, Cornell University, Ithaca, NY 14853, USA d Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA e NASA Johnson Space Center, Houston, TX 77058, USA f Lockheed-Martin Space Operations, 2400 NASA Rd. 1, Houston, TX 77058, USA g California State University at San Bernadino, San Bernadino, CA 92407, USA h NASA/Goddard Space Flight Center, Greenbelt, MD 20071, USA i Cornell University, 610 Space Sciences Bldg., Ithaca, NY 14853, USA j Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA k University of Maine, Farmington, Farmington, 336 Preble Hall, ME 04938, USA l University of Michigan, 3048 FXB, Ann Arbor, MI 48109, USA m Astronomical Institute, Ondrejov, Czech Republic n MMT Observatory, PO Box 210065, University of Arizona, Tucson, AZ 85721, USA |
| Abstract: | We observed near-Earth asteroid (NEA) 2100 Ra-Shalom over a six-year period, obtaining rotationally resolved spectra in the visible, near-infrared, thermal-infrared, and radar wavelengths. We find that Ra-Shalom has an effective diameter of Deff=2.3±0.2 km, rotation period P=19.793±0.001 h, visual albedo pv=0.13±0.03, radar albedo  , and polarization ratio μc=0.25±0.04. We used our radar observations to generate a three-dimensional shape model which shows several structural features of interest. Based on our thermal observations, Ra-Shalom has a high thermal inertia of ∼103 J m−2 s−0.5 K−1, consistent with a coarse or rocky surface and the inferences of others Harris, A.W., Davies, J.K., Green, S.F., 1998. Icarus 135, 441-450; Delbo, M., Harris, A.W., Binzel, R.P., Pravec, P., Davies, J.K., 2003. Icarus 166, 116-130]. Our spectral data indicate that Ra-Shalom is a K-class asteroid and we find excellent agreement between our spectra and laboratory spectra of the CV3 meteorite Grosnaja. Our spectra show rotation-dependent variations consistent with global variations in grain size. Our radar observations show rotation-dependent variations in radar albedo consistent with global variations in the thickness of a relatively thin regolith. |
| Keywords: | Asteroids Asteroids composition Asteroids surfaces Radar observations |
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