Multi-wavelength observations of Asteroid 2100 Ra-Shalom

Michael K. Shepard, Beth Ellen Clark, Michael C. Nolan, Lance A.M. Benner, Steven J. Ostro, Jon D. Giorgini, Faith Vilas, Kandy Jarvis, Susan Lederer, Lucy F. Lim, Tim McConnochie, James Bell, Jean Luc Margot, Andrew Rivkin, Christopher Magri, Daniel Scheeres, Petr Pravec

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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 over(σ, ̂)OC = 0.36 ± 0.10, 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.

Original languageEnglish (US)
Pages (from-to)20-38
Number of pages19
JournalIcarus
Volume193
Issue number1
DOIs
StatePublished - Jan 1 2008
Externally publishedYes

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Keywords

  • Asteroids
  • Radar observations
  • composition
  • surfaces

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Shepard, M. K., Clark, B. E., Nolan, M. C., Benner, L. A. M., Ostro, S. J., Giorgini, J. D., Vilas, F., Jarvis, K., Lederer, S., Lim, L. F., McConnochie, T., Bell, J., Margot, J. L., Rivkin, A., Magri, C., Scheeres, D., & Pravec, P. (2008). Multi-wavelength observations of Asteroid 2100 Ra-Shalom. Icarus, 193(1), 20-38. https://doi.org/10.1016/j.icarus.2007.09.006