Browsing by Author "Fraser, Wesley C."

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    174P/Echeclus and Its Blue Coma Observed Post-outburst
    (2019) Seccull, Tom; Fraser, Wesley C.; Puzia, Thomas H.; Fitzsimmons, Alan; Cupani, Guido
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    2004 EW95: A Phyllosilicate-bearing Carbonaceous Asteroid in the Kuiper Belt
    (2018) Seccull, Tom; Fraser, Wesley C.; Puzia, Thomas H.; Brown, Michael E.; Schoenebeck, Frederik
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    Near-UV Reddening Observed in the Reflectance Spectrum of High-inclination Centaur 2012 DR30
    (2021) Seccull, Tom; Fraser, Wesley C.; Puzia, Thomas H.
    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.
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    The Reflectance of Cold Classical Trans-Neptunian Objects in the Nearest Infrared
    (2021) Seccull, Tom; Fraser, Wesley C.; Puzia, Thomas H.
    Recent photometric surveys of Trans-Neptunian Objects (TNOs) have revealed that the cold classical TNOs have distinct z-band color characteristics and occupy their own distinct surface class. This suggested the presence of an absorption band in the reflectance spectra of cold classicals at lambda > 0.8 mu m. Here we present reflectance spectra spanning 0.55-1.0 mu m for six TNOs occupying dynamically cold orbits at a similar to 44 au. Five of our spectra show a clear and broadly consistent reduction in spectral gradient above 0.8 mu m that diverges from their linear red optical continuum and agrees with their reported photometric color data. Despite predictions, we find no evidence that the spectral flattening is caused by an absorption band centered near 1.0 mu m. We predict that the overall consistent shape of these five spectra is related to the presence of similar refractory organics on each of their surfaces, and/or their similar physical surface properties such as porosity or grain size distribution. The observed consistency of the reflectance spectra of these five targets aligns with predictions that the cold classicals share a common history in terms of formation and surface evolution. Our sixth target, which has been ambiguously classified as either a hot or cold classical at various points in the past, has a spectrum that remains nearly linear across the full range observed. This suggests that this TNO is a hot classical interloper in the cold classical dynamical range and supports the idea that other such interlopers may be identifiable by their linear reflectance spectra in the range 0.8-1.0 mu m.