The following document lists the file abstract/SDERMOTT_ZCPOLES1.abs
from catalogue VI/111.
A plain copy of the file
(without headers/trailers) may be downloaded.
Using ISO we propose to confirm the existence of asymmetries in the zodiacal cloud discovered by analzing COBE data from the North and South ecliptic poles. This work is an extension of a previous proposal, SDERMOTT.ETRING_1, to investigate the structure of the zodiacal cloud. While the COBE data provides excellent results of great scientific significance, COBE only observed for 9 months of the year. Hence, we need results from ISO to cover the remaining 3 months with a slight amount of overlap so that comparisons can be made with the existing COBE data. Using the 25 micron wave band COBE data on the variation with the longitude of Earth of the brightness of the North and South ecliptic poles, we have determined the variation of the number density of particles in the zodiacal cloud with heliocentric distance and discovered that it does not follow a simple Poynting-Robertson light drag model, implying either that asteroidal particles are lost from the system as they spiral in towards the Sun and/or that the cloud has a significant component of cometary material. More ISO data will produce a better fit to our existing data and thus a more accurate measure of the number density gradient. By looking at the COBE ecliptic pole data near the Earth's apocenter, we have also determined that the center of rotational symmetry of the cloud is displaced from the Sun. However, we are missing essential data near the Earth's pericenter which ISO could provide. Finally, the COBE ecliptic pole data has allowed us to place constraints on the percentage of the zodiacal cloud that is asteroidal in origin. Additional ISO data for the three months missed by COBE will help us place an even tighter constraint on this percentage. Even if ISO observations are obtained only in the 25 micron wave band, which is our first priority, they will be highly useful. However, in order of decreasing priority, we would also like the same set of observations to be made at 11.5, 60, and 4.85 microns. Understanding the structure and dynamics of the zodiacal cloud will help us interpret observations of the structure and evolution of disks around other stars. It will also place constraints on the collisional evolution of the asteroid belt and the long-term transport of cometary material to the inner solar system.