Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published February 1, 2007 | Published + Accepted Version
Journal Article Open

The Surface of 2003 EL_(61) in the Near-Infrared


We report the detection of crystalline water ice on the surface of 2003 EL_(61). Reflectance spectra were collected from the Gemini North telescope in the 1.0 to 2.4 μm wavelength range and from the Keck telescope across the 1.4-2.4 μm wavelength range. The signature of crystalline water ice is obvious in all data collected. Like the surfaces of many outer solar system bodies, the surface of 2003 EL_(61) is rich in crystalline water ice, which is energetically less favored than amorphous water ice at low temperatures, suggesting that resurfacing processes may be taking place. The near-infrared color of the object is much bluer than a pure water ice model. Adding a near-infrared blue component such as hydrogen cyanide or phyllosilicate clays improves the fit considerably, with hydrogen cyanide providing the greatest improvement. The addition of hydrated tholins and bitumens also improves the fit, but is inconsistent with the neutral V - J reflectance of 2003 EL_(61). A small decrease in reflectance beyond 2.3 μm may be attributable to cyanide salts. Overall, the reflected light from 2003 EL_(61) is best fit by a model of 2/3-4/5 pure crystalline water ice and 1/3-1/5 near-infrared blue component such as hydrogen cyanide or kaolinite. The surface of 2003 EL_(61) is unlikely to be covered by significant amounts of dark material such as carbon black, as our pure ice models reproduce published albedo estimates derived from the spin state of 2003 EL_(61).

Additional Information

© 2007 American Astronomical Society. Print publication: Issue 2 (2007 February 1); received 2006 January 20; accepted for publication 2006 September 24. We appreciate the comments of the anonymous referee who reviewed this work. We thank the Gemini science staff who scheduled our program, operated the telescope, and collected the queue mode data: Tracy Beck, Julia Bodnarik, Simon Chan, Avi Fhima, Rachael Johnson, Inger Jørgensen, Andrew Stephens, Kevin Volk, and Dolores Walther. We thank the observing assistants and support astronomers at the W.M. Keck Observatory who helped with this project: Marc Kassis, Chuck Sorenson, and Steven Magee. This work was based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation (NSF) on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council No. 2, 2007 2003 EL61 IN NIR 1177 (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq ( Brazil) and CONICET (Argentina). Observations were collected under Gemini program IDs GN-2004BQ-56 and GN-2005A-Q-45. Some of the data presented here were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Attached Files

Published - TRUapj07a.pdf

Accepted Version - 0601618.pdf


Files (1.4 MB)
Name Size Download all
717.2 kB Preview Download
692.6 kB Preview Download

Additional details

August 22, 2023
October 19, 2023