Dr. Maria WomackUniversity of South Florida
Comets are well-preserved samples
of the gas and grains of the protosolar nebula cloud out of which the solar
system formed, and thus, they provide an excellent opportunity to study the
formation of the solar system. Most comet activity is driven by the
sublimation of frozen water, the most abundant ice in comets. Some comets, however,
are active well beyond the water-ice sublimation limit of ∼ 3
AU from the Sun, and this activity is driven by the out-gassing
of CO, and possibly CO2, molecules, possibly
trapped in an amorphous water ice surface undergoing crystallization. Since
water-ice sublimation is suppressed far from the Sun, studying distantly active
comets provides a good platform for testing models of cometary composition, physics
of comae, and thermal processing of icy comet nuclei. We will look at several examples of observing distantly active comets
with millimeter-wavelength spectroscopy (including emission maps and spectral
line profiles) of CO and other gases, and discuss possible implications. Much of this work is also applicable to the larger problem of
modeling the behavior of CO, and other super-volatiles, in other outer solar
system icy objects.
Read More