Near-UV Reddening Observed in the Reflectance Spectrum of High-inclination Centaur 2012 DR<sub>30</sub>
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Date
2021
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Abstract
Centaurs with high orbital inclinations and perihelia (i > 60 degrees; q greater than or similar to 5 au) are a small group of poorly understood minor planets that are predicted to enter the giant planet region of the solar system from the inner Oort Cloud. As such, they are one of the few samples of relatively unaltered Oort Cloud material that can currently be directly observed. Here we present two new reflectance spectra of one of the largest of these objects, 2012 DR30, in order to constrain its color and surface composition. Contrary to reports that 2012 DR30 has variable optical color, we find that consistent measurements of its spectral gradient from most new and published data sets at 0.55-0.8 mu m agree with a spectral gradient of S ' similar or equal to 10% +/- 1%/0.1 mu m 30 at near-UV/blue and near-IR wavelengths, however, is still relatively unconstrained; self-consistent rotationally resolved follow-up observations are needed to characterize any spectral variation in those regions. We tentatively confirm previous detections of water ice on the surface of 2012 DR30, and we also consistently observe a steady steepening of the gradient of its spectrum from lambda similar to 0.6 mu m toward near-UV wavelengths. Plausible surface materials responsible for the observed reddening may include ferric oxides contained within phyllosilicates and aromatic refractory organics.