Near-Infrared Spectra of Centaurs and Kuiper Belt Objects

Abstract

We present here an extensive survey of near-infrared (NIR) spectra of Kuiper belt objects (KBOs) and Centaurs taken with the Keck I Telescope. We find that most spectra in our sample are well characterized by a combination of water ice and a featureless continuum. A comparative analysis reveals that the NIR spectral properties have little correlation to the visible colors or albedo, with the exception of the fragment KBOs produced from the giant impact on 2003 EL61. The results suggest that the surface composition of KBOs is heterogeneous, though the exposure of water ice may be controlled by geophysical processes. The Centaurs also display diverse spectral properties, but the source of the variability remains unclear. The results for both the KBOs and the Centaurs point to inherent heterogeneity in either the processes acting on these objects or materials from which they formed.

New insights on ices in Centaur and Transneptunian populations

“…4), as reported by previous authors . The depth of this band seems slightly different between the three different spectra even if the signal to noise ratio is more limited for the data of Barkume et al (2008) and Pinilla-Alonso et al (2007). The slope in the near infrared is similar in the three cases as well as the slope observed in the visible spectra.…”

“…We obtained near-infrared spectra for 12 Barkume et al 2008). Our spectrum shows the presence of crystalline water ice because of a strong absorption feature at 1.65 µm (see Fig.…”

Atmospheres and surfaces of small bodies and dwarf planets in the Kuiper Belt

“…4). Barkume et al [38] found a weak correlation between object size and the fraction of water ice detected on the surfaces of the KBOs in their sample indicating that larger objects generally show stronger water ice absorption features. However, no such correlation was found for the Centaurs [38].…”

“…To first order, the surfaces of small and midsized KBOs and centaurs can be described with a two-component model consisting of dark (likely carbon-rich) deposits and exposed crystalline water ice [7,38]. The spectra of these objects can be parameterized as a linear mixture between a featureless continuum component (with a variable slope) and crystalline water ice [7,38].…”

“…The spectra of these objects can be parameterized as a linear mixture between a featureless continuum component (with a variable slope) and crystalline water ice [7,38]. The fraction, f, of water ice the spectra can then be compared with object size, orbital properties and object colour.…”