Observations of X/M asteroids across multiple wavelengths

Maureen E. Ockert-Bell, Beth Ellen Clark, Michael K. Shepard, Andrew S. Rivkin, Richard P. Binzel, Cristina A. Thomas, Francesca E. DeMeo, S. J. Bus, Sweta Shah

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We have conducted a radar-driven observational campaign of main-belt asteroids (MBAs) focused on X/M class asteroids using the Arecibo radar and NASA Infrared Telescope Facilities (IRTF). M-type asteroids have been identified as metallic, enstatite chondrites and/or heavily altered carbonaceous chondrites [Bell, J.F., Davis, D., Hartmann, W.K., Gaffey, M.J., 1989. In: Binzel, R.P., Gehrels, T., Matthews, M.S. (Eds.), Asteroids II. Univ. of Arizona Press, Tucson, pp. 921-948; Gaffey, M.J., McCord, T.B., 1979. In: Gehrels, T., Matthews, M.S. (Eds.), Asteroids. Univ. of Arizona Press, Tucson, pp. 688-723; Vilas, F., 1994. Icarus 111, 456-467]. Radar wavelength observations can determine whether an asteroid is metallic and provide information about the porosity and regolith depth. Near-infrared observations can help determine the grain size, porosity and composition of an object. Concurrent observations with these tools can give us a wealth of information about an object. Our objectives for this observation program were to (a) determine if there are any consistent relationships between spectra in the near-infrared wavelengths and radar signatures and (b) look for rotationally resolved relationships between asteroid radar properties and near-infrared spectral properties. This paper describes preliminary results of an ongoing survey of near-infrared observations of M-type asteroids and is a companion paper to radar observations reported by Shepard [Shepard, M.K., and 19 colleagues, 2008a. Icarus 195, 184-205]. In the analysis of 16 asteroid near-infrared spectra and nine radar measurements, we find a trend indicating a correlation between continuum slope from 1.7 to 2.45 μm and radar albedo-an asteroid with a steep continuum slope also has a bright radar albedo, which suggests a significant metal content. This may provide a means to use near-IR observations to predict the most likely metallic candidates for radar studies.

Original languageEnglish (US)
Pages (from-to)206-219
Number of pages14
Issue number1
StatePublished - May 2008
Externally publishedYes


  • Asteroids
  • composition
  • surfaces

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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