The following document lists the file abstract/JSCOTTI_COMNUC.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
The size distribution of short-period comets, although crucial for assessing theories of their origin (e.g. whether from the Kuiper belt, the inner core of the Oort cloud or the observed long-period flux), remains largely uncertain. Most current estimates of cometary diameters depend on assumed visual albedos together with nuclear magnitude estimates, or on arguments based on outgassing due to water-ice sublimation and assumptions about the fractional active surface area. Accurate measurements of the size depend on infrared measurements in the 10 to 100 micron range (depending on the temperature of the nucleus), and currently only some 5 objects have reliably determined diameters. The sensitivity of ISO provides an opportunity to observe a substantial number of Jupiter-family comets, currently moving in a variety of typical short-period cometary orbits. We propose to use ISO to observe a number of these comets relatively far from the sun in order to determine the sizes of their nuclei while they are comparatively inactive and uncontaminated by coma. The proposed program will more than double the sample of accurate diameters of short-period cometary nuclei, and combined with contemporary visual observations will also allow accurate determinations of their visual geometric albedos.