Near-infrared Photometric Search For Volatile Ices On The Surfaces Of Cold Classical Kuiper Belt Objects
Abstract
The surprisingly complex dynamic distribution of small bodies among and beyond the orbits of the planets has changed our understanding of Solar System evolution. Compositional information about the small bodies in the Solar System provides constraints for emerging models of Solar System formation. The cold classical Kuiper Belt population is particularly interesting; according to the Nice model, cold classicals have not migrated much from where they formed, 42 - 45 AU. At these distances, the cold classicals have undergone little thermal evolution and we expect them to be rich with volatile ices of diverse composition (H2O, N2, CH4, light hydrocarbons, e.g. CH3OH). Despite this expectation, Barucci et al. (2011) find no evidence for ices in their sample (3 objects) of cold classical objects. Broad absorption features from most, if not all, volatile ices occur at λ > 2.5 µm. Absorptions are identified using a combination of JHK bands on terrestrial IR telescopes and the 3.6 µm and 4.5 µm channels of the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. Increasing the wavelength range of data with IRAC observations further constrains the composition of materials on KBO surfaces. We report IRAC measurements of reflectances of 45 cold classical KBOs. These longer wavelength albedos are added to ground-based NIR data to extend the KBOs' known spectra to a broader range. Upper limits for the bands at which the objects were not detected provide useful constraints as well. Compositional spectral modeling is used to match the observed photometry from the more completely observed objects with laboratory spectra. We expect volatiles to be uniformly distributed with respect to orbital parameters, such as semi-major axis, inclination, eccentricity, and perihelion, and physical properties, such as absolute magnitude and size. Support for this work was provided by NASA through an award issued by JPL/Caltech.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #44
- Pub Date:
- October 2012
- Bibcode:
- 2012DPS....4440503W