First Ultraviolet Reflectance Spectra of Pluto and Charon by the Hubble Space Telescope Cosmic Origins Spectrograph: Detection of Absorption Features and Evidence for Temporal Change
Stern, S. A.; Spencer, J. R.; Cunningham, N. J.; Hain, M. J.; Shinn, A.
United States
Abstract
We have observed the mid-UV spectra of both Pluto and its large satellite, Charon, at two rotational epochs using the Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) in 2010. These are the first HST/COS measurements of Pluto and Charon. Here we describe the observations and our reduction of them, and present the albedo spectra, average mid-UV albedos, and albedo slopes we derive from these data. These data reveal evidence for a strong absorption feature in the mid-UV spectrum of Pluto; evidence for temporal change in Pluto's spectrum since the 1990s is reported, and indirect evidence for a near-UV spectral absorption on Charon is also reported.