TY - JOUR
T1 - Asteroid 21 Lutetia at 3μm
T2 - Observations with IRTF SpeX
AU - Rivkin, Andrew S.
AU - Clark, Beth E.
AU - Ockert-Bell, Maureen
AU - Volquardsen, Eric
AU - Howell, Ellen S.
AU - Bus, Schelte J.
AU - Thomas, Cristina A.
AU - Shepard, Michael
N1 - Funding Information:
This research has made use of IMCCE’s Miriade VO tool. Our thanks to Benoit Carry, who provided much useful information and enabled us to determine Lutetia’s aspect at the times of our (and other) observations. Our observations were funded by Grant NNG05GR60G from the NASA Planetary Astronomy Program , and reduction and analysis by Grant NNX1AG40G from the NASA Planetary Geology and Geosciences Program . Continued thanks to the people of Hawaii for allowing us to use Mauna Kea for observations, and continued thanks to the stalwart telescope operators of the NASA IRTF. Merci beaucoup to Richard Binzel. Some of the data utilized in this publication were obtained and made available by the MIT-UH-IRTF Joint Campaign for NEO Reconnaissance. The MIT component of this work is supported by the National Science Foundation under Grant No. 0506716 . Encouraging reviews by Antonella Barucci and Francesca DeMeo helped strengthen this work.
PY - 2011/11
Y1 - 2011/11
N2 - 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.
AB - 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.
KW - Asteroids
KW - Asteroids, Composition
KW - Asteroids, Surfaces
KW - Spectroscopy
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U2 - 10.1016/j.icarus.2011.08.009
DO - 10.1016/j.icarus.2011.08.009
M3 - Article
AN - SCOPUS:80052721487
SN - 0019-1035
VL - 216
SP - 62
EP - 68
JO - Icarus
JF - Icarus
IS - 1
ER -