Cosmic dust: Encyclopedia II - Cosmic dust - Introductory Material

Cosmic dust - Introductory Material

Cosmic Dust refers to particles in space which are assemblages of a few molecules to tenth-millimeter-sized grains. Cosmic dust can be further distinguished by its astronomical location; for example: interplanetary dust, interstellar dust, comet dust, circumplanetary dust. This article covers bulk and radiative properties of cosmic dust, the dust particles' origins, end-fates, and specific locations in space.

Historically, cosmic dust used to be an annoyance to astronomers because of the way that the dust obscures the object that they wish to observe. When the field of infrared astronomy began, those so-called annoying dust particles were observed to be significant constituents of the Universe and found to be vital components of astrophysical processes.

For example, the dust can drive the mass loss that occurs when a star is nearing the end of its life, those particles are an essential part of the early stages of star formation, and they form planets around other stars. In our own solar system, dust plays a major role in the zodiacal light, Saturn's B Ring spokes, the outer diffuse planetary rings at Jupiter, Saturn, Uranus and Neptune, the resonant dust ring at the Earth, and the overall behavior of comets.

The study of dust is a many-faceted research topic that brings together different scientific fields: physics (solid-state, electromagnetic theory, surface physics, statistical physics, thermal physics), math (fractal math), chemistry (chemical reactions on grain surfaces), meteoritics, as well as every branch of astronomy and astrophysics. While being multidisciplinary, the disparate research areas can be linked by the following theme: the cosmic dust particles evolve cyclically; chemically, physically and dynamically. The evolution of dust traces out paths in which the universe recycles material, in processes analogous to the daily recycling steps with which many people are familiar: production, storage, processing, collection, consumption, and discarding. Observations and measurements of cosmic dust in different regions provide an important insight into the universe's recycling processes; in the clouds of the diffuse interstellar medium, in molecular clouds, in the circumstellar dust of young stellar objects, and in planetary systems such as our own solar system, where astronomers consider dust as in its most recycled state. The astronomers accumulate observational ‘snapshots’ of dust at different stages of its life and, over time, form a more complete movie of the universe's complicated recycling steps.

The detection of cosmic dust points to another facet of cosmic dust research: dust acting as photons. Once cosmic dust is detected, the scientific problem to be solved is an inverse problem to determine what processes brought that encoded photon-like object (dust) to the detector. Parameters such the particle's initial motion, material properties, intervening plasma and magnetic field determined the dust particle's arrival at the dust detector. Slightly changing any of these parameters can give significantly different dust dynamical behavior. Therefore one can learn about where that object came from, and what is (in) the intervening medium.

Adapted from the Wikipedia article "Introductory Material", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki