Asteroid 21 Lutetia at 3μm: Observations with IRTF SpeX

Andrew S. Rivkin, Beth E. Clark, Maureen Ockert-Bell, Eric Volquardsen, Ellen S. Howell, Schelte J. Bus, Cristina A. Thomas, Michael Shepard

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We present observations of Asteroid 21 Lutetia collected 2003-2008 using the SpeX instrument on the NASA Infrared Telescope Facility (IRTF) covering 2-4 μm. We also reevaluate NSFCam observations obtained in 1996 (Rivkin, A.S., Lebofsky, L.A., Clark, B.E., Howell, E.S., Britt, D.T. [2000]. Icarus 145, 351-368). Taken together, these show deeper 3-μm band depths (of order 3-5%) in the southern hemisphere of Lutetia, and shallower band depths (of order 2% or less) in the north. Such variation is consistent with observations at shorter wavelength by previous workers (Nedelcu, D.A. et al. [2007]. Astron. Astrophys. 470, 1157-1164; Lazzarin, M. et al. [2010]. Mon. Not. R. Astron. Soc. 408, 1433-1437), who observed hemispheric-level variations from C-like spectra to X-like spectra. While the shallowness of absorption bands on Lutetia hinders identification of its surface composition, goethite appears plausible as a constituent in its southern hemisphere (Beck, P., Quirico, E., Sevestre, D., Montes-Hernandez, G., Pommerol, A., Schmitt, B. [2011]. Astron. Astrophys. 526, A85-A89). Mathematical models of space weathered goethite are most consistent with Lutetia's southern hemisphere spectrum, but more work and further observations are necessary to confirm this suggestion.

Original languageEnglish (US)
Pages (from-to)62-68
Number of pages7
Issue number1
StatePublished - Nov 2011


  • Asteroids
  • Asteroids, Composition
  • Asteroids, Surfaces
  • Spectroscopy

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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