The 'interplanetary dust cloud' has been studied for many years in order
to understand its nature, origin, and relationship to
planetary systems
(our own, as well as extrasolar systems).
The
interplanetary dust particles (IDPs) not only scatter solar light
(called the "
zodiacal light", which is confined to the
ecliptic plane), the IDPs also produce
thermal emission,
which is the most prominent feature of the night-sky light
in the 5-50 micrometer wavelength domain (Levasseur-Regourd, A.C.
1996). The grains characterizing the infrared emission near the
earth's
orbit have typical sizes of 10-100
micrometers (Backman, D.,
1997). The total mass of the interplanetary dust cloud is about the
mass of an
asteroid of radius 15 km (with density of about 2.5
g/cm
3).
The sources of IDPs include at least: asteroid collisions,
cometary
activity and collisions in the inner solar system,
Kuiper Belt
collisions, and interstellar medium (ISM) grains (Backman, D., 1997). Indeed, one of the
longest-standing controversies debated in the interplanetary dust
community revolves around the relative contributions to the
interplanetary dust cloud from asteroid collisions and cometary
activity.
The main physical processes "affecting" (destruction or expulsion
mechanisms) IDPs are: expulsion by
radiation pressure, inward
Poynting-Robertson (PR) radiation drag,
solar wind pressure (with
significant electromagnetic effects),
sublimation, mutual collisions,
and the dynamical effects of planets (Backman, D., 1997).
The lifetimes of these dust particles are very short compared to the
lifetime of the
Solar System. If one finds grains around a star that is older
than about 10^8 years, then the grains must have been from recently
released fragments of larger objects, i.e. they cannot be leftover
grains from the
protoplanetary disk (Backman, private
communication). Therefore, the grains would be "later-generation"
dust. The zodiacal dust in the solar system is 99.9% later-generation
dust and 0.1% intruding ISM dust. All primordial grains from the Solar System's formation were removed long ago.
The interplanetary dust cloud has a complex structure (Reach, W., 1997). Apart from a background density, this includes:
★ At least 8
dust trails -- their source is thought to be short-period comets.
★ A number of dust bands, the sources of which are thought to be
asteroid families in the
main asteroid belt. The three strongest bands arise from the
Themis family, the
Koronis family, and the
Eos family. Other source families include the
Maria,
Eunomia, and possibly the
Vesta and/or
Hygiea families (Reach et al 1996).
★ at least 2 resonant dust rings are known (for example, the Earth-resonant dust ring, although every planet in the solar system is thought to have a resonant ring with a "wake") (Jackson and Zook, 1988, 1992) ,(Dermott, S.F. et al., 1994, 1997)
References
A Solar System Dust Ring with the Earth as its Shepherd, Jackson A.A.; Zook, H.A., , , Nature, 1988
Orbital evolution of dust particles from comets and asteroids, Jackson A.A.; Zook, H.A., , , Icarus, 1992
See:
[1]
RA circumsolar ring of asteroid dust in resonant lock with the Earth, Dermott, S.F. Jayaraman, S., Xu, Y.L., Gustafson, A.A.S., Liou, J.C.,, , , Nature, June 30, 1994
The Three-Dimensional Structure of the Zodiacal Dust Bands, Reach, W.T.; Franz, B.A.; Weiland, J.L., , , Icarus, 1997