The following document lists the file abstract/ASTERN_CHIR_PL.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
Chiron, pluto, and Triton are among the most exciting bodies in the outer solar system. These three objects are known to have surfaces dominated by volatile frosts and may as a group represent our best link to planetesimals from the early solar system. Each apparently accreted in the region beyond 30 AU, grew to a size logarithmically intermediate between comets and the giant planets, and developed a volatile rich veneer that generates a tenuous atmosphere. There are already indications that Pluto and perhaps Chiron exhibit both sublimating (icy) and non-sublimating (inert) surfaces. It is expected that the surface temperature of these bodies is correlated with the cold (sublimating) and warm (non-sublimating) regions. Although there is no evidence that Triton exhibits thermally-distinct surface units now, it is likely to develop them at some points in its complex seasonal cycles. Triton is too close to Neptune to be studied by ISO. However, Chiron and the Pluto-Charon binary (PCB) are ideal targets for thermal studies by ISO. This proposal offers to explore the thermal properties of Chiron and Pluto with a program of (i) ISOPHOT observations designed to obtain dense thermal lightcurves for these bodies at high S/N in various wavebands across their spectral energy distributions, and (ii) LWS characterization spectra of each target. We will invert the data lightcurves to determine or constrain the distributions and areal extents of hot and cold regions, and to identify and remove the signal from Pluto's satellite Charon from the PCB lightcurves for the first time. The Chiron measurements may also be able to further refine estimates of its diameter. As we describe below, ISO provides the only available means to resolve the thermal controversies now surrounding Chiron and the PCB, and to constrain the distribution of active areas on their surfaces. The results obtained will also have application to Triton, and possibly to the suite of related, Chiron-like "Centaurs" and more distant Kuiper Disk mini-planets now being discovered beyond 30 AU.