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Session 34 - Solar System.
Display session, Tuesday, June 11
Tripp Commons,

[34.04] HST Observations of Ultraviolet Reflectance Properties of Outer Solar System Objects: Triton and Chiron

S. A. Stern, J. W. Parker (SwRI), E. Bowell, M. Buie (Lowell Obs), B. Bus (MIT), M. Festou (Obs. Midi-Pyrénées), B. Flynn (CEA/UCB), M. A'Hearn (U. Maryland), L. M. Trafton (McDonald Obs.), D. Weintraub (Vanderbilt U.)

The Hubble Space Telescope\/ has provided unprecedented opportunities to obtain ultraviolet spectroscopy of outer Solar System objects. In this paper we present the results of HST/FOS\/ projects to study the ultraviolet properties of surface and gaseous components of the largest satellite of Neptune and of one of the most accessible possibly former members of the Kuiper Belt: Triton and Chiron. The visible red color slope of Triton ends at \sim2750 Åwith a blue albedo upturn or a possible broad and shallow absorption feature. In contrast, Chiron's color is indistinguishable from grey, with a geometric albedo of 0.07 \pm 0.01. Its light curve has a peak-to-peak variation of 7 \pm 1%, similar to that of the visible light curve. Triton's UV light curve also appears to be similar in structure to its optical light curve, but the HST\/ UV data show that the amplitude of the light curve monotonically increases to shorter wavelengths. Concerning the atmospheres of these two bodies, we have obtained upper limits for features such as OH, Mg, NO, and CO.

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