Dust Grain
The structure of an interstellar dust grain
Interstellar dust grains have their origin in the material ejected by stars.
Most analyses of the extinction, absorption and scattering efficiencies of interstellar dust grains use the Mie theory, which solves for the exact electromagnetic fields in a spherical or cylindrical dust grain.
Dust grains
Dust grains can be found scattered throughout the galaxy, as long as the temperature is not high enough (several thousand kelvins) to evaporate the grains.
dust grain An interstellar dust particle, roughly 10&150;8 m in size, comparable to the wavelength of visible light.
dust lane A lane of dark, obscuring interstellar dust in an emission nebula or galaxy.
Dust grains
not the dust one finds around the house, which is typically fine bits of fabric, dirt, or dead skin cells.
[edit] Dust grain formation
The large grains start with the silicate particles forming in the atmospheres of cool stars, and carbon grains in the atmospheres of cool carbon stars.
dust grain A term for dust particles in the space between the stars. Sizes vary over a wide range but are typically about one micrometer, comparable to the wavelength of visible light.
The dust grains in comets absorb light from the Sun. This causes the dust grains to heat up and glow in the infrared.
The dust grains are suspected to be on average smaller that in our Solar system, with typical diameters below one micrometre (equivalent to particles constituting cigarette smoke).
How the dust grains experienced these extremes of environments could, in part, be explained by a popular theory known as the X-wind model.
Interestingly, most dust grains in the disk are not agglomerating to form larger bodies; instead, they are eroding and being moved away from the star by radiation pressure when their size goes below about 2-10 microns.
The cloud complex had already been ``polluted'' with dust grains from previous generations of stars, so it was possible to form the rocky terrestrial planets. As the piece, called the solar nebula collapsed, its slight rotation increased.
For thermal emission, dust grains are heated by absorption of starlight, which operates most effectively in the blue and UV as the wavelength comes closer to the characteristic grain size.
A star forms when a dense interstellar cloud of hydrogen and dust grains collapses inward under the force of its own gravity. As the cloud condenses, its density and internal temperature increase until reaching incandescence with a faint red glow.
The dust grains escape the weak gravity of the nucleus and travel on their own independent, heliocentric orbits.
Throughout the disk, dust grains orbiting the proto-Sun collided with one another, occasionally sticking together. Small clumps joined together to make ever larger ones, eventually forming the planets.
The particles are composed of common heavy elements such as carbon and silicon but there is no agreement about the exact composition of the dust grains.
The birth of stars is intimately connected with the presence of dust grains and molecules, as in the Orion nebula region of earth's galaxy. Here, molecular hydrogen (H2) is compressed to high densities and temperatures, dissociating the molecules.
Most of this material is in the form of atomic gas and dust grains (only a few molecules, like PAHs, can survive the rigors of the high radiation fields in this environment).
The interstellar medium consists of an extremely dilute (by terrestrial standards) mixture of ions, atoms, molecules, larger dust grains, cosmic rays, and magnetic fields. The matter consists of about 99% gas and 1% dust by mass.
The dust is blown away from the coma by radiation pressure from the sunlight absorbed by individual dust grains.
The ISM consists of an extremely dilute (by terrestrial standards) plasma, gas and dust, consisting of a mixture of ions, atoms, molecules, larger dust grains, electromagnetic radiation, cosmic rays, and magnetic fields.
Long-wave infrared observations reveal a disk, probably from heated radiating dust grains, intriguingly similar to our Sun's extended "Kuiper Belt, ...
Dust grains are a major component of the interstellar medium. Dust blocks visible light causing interstellar extinction.
These 10-micron dust grains are already moving at a nice click when they pick up their hitchhikers. Then a supernova blast comes and kicks them to cosmic-ray speeds.
Sakurai's Object has ejected a large amount of the carbon from its inner core into space, both in the form of gas and dust grains.
The mission will also collect samples of interstellar dust grains. Other objectives involve imaging the comet nucleus and preliminary analysis of the composition of the cometary dust particles.
They appear bluish due to the dust grains preferentially scattering blue light from nearby hot stars. Our sky appears blue for much the same reason, blue light from the Sun is scattered in all directions.
Cosmic Dust Analyzer that studies ice and dust grains in and near the Saturn system
Dual Technique Magnetometer that studies Saturn's magnetic field and its interactions with the rings, the moons, and the solar wind ...
Light is scattered off of dust grains, so that a distant star appears dimmer than it otherwise would. The scattering process is most effective at short (blue) wavelengths, so that stars seen through inter- stellar dust appear reddened and dimmed.
A widely accepted theory of planet formation, the so-called planetesimal hypothesis of Viktor Safronov, states that planets form out of dust grains that collide and stick to form larger and larger bodies....
A solid object that is believed to exist in protoplanetary disks and in debris disks. Planetesimals are formed from small dust grains that collide and stick together and are the building blocks that eventually form planets in new planetary systems.
In the case of young stars, accretion disks contain unconsolidated material, such as cosmic dust grains, which may subsequently accrete to form planets and other sizable objects (see planetary systems, formation).
These are primarily hydrogen and helium atoms, which are mostly not affected by magnetic fields, and there are also heavier dust grains. These interstellar neutral particles make up a substantial fraction of the material found within the heliosphere.
molecular clouds (NASA Thesaurus) Thickest and densest interstellar clouds consisting mainly of molecular hydrogen but also a high concentration of dust grains.
 See also: Dust grains, Dust, Light, Solar, Sun
  
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