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Cosmic dust – also called extraterrestrial dust, space dust, or star dust – is dust that occurs in outer space or has fallen onto Earth. [ 1 ] [ 2 ] Most cosmic dust particles measure between a few molecules and 0.1 mm (100 μm ), such as micrometeoroids (<30 μm) and meteoroids (>30 μm). [ 3 ]
Intergalactic dust can form intergalactic dust clouds, known since the 1960s to exist around some galaxies. [1] By the 1980s, at least four intergalactic dust clouds had been discovered within several megaparsecs of the Milky Way galaxy, [ 1 ] exemplified by the Okroy Cloud .
A dust lane consists of relatively dense, obscuring clouds of interstellar dust, observed as a dark swath against the background of brighter object(s), especially a galaxy. These dust lanes can usually be seen in spiral galaxies , such as the Milky Way , when viewed from the edge.
As in all real images from our Arm of the galaxy much is obscured by the Great Rift, dark dust clouds that span from Cygnus to Centaurus. In astronomy , the Great Rift (sometimes called the Dark Rift or less commonly the Dark River ) is a dark band caused by interstellar clouds of cosmic dust that significantly obscure ( extinguish ) the center ...
For example, some regions of the Galactic Center are awash with obvious intervening dark dust from our spiral arm (and perhaps others) and themselves in a bulge of dense matter, causing as much as more than 30 magnitudes of extinction in the optical, meaning that less than 1 optical photon in 10 12 passes through. [10]
An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. But differently, an interstellar cloud is a denser-than-average region of the interstellar medium , the matter and radiation that exists in the space between the star systems in a galaxy.
Dust astronomy is a subfield of astronomy that uses the information contained in individual cosmic dust particles ranging from their dynamical state to its isotopic, elemental, molecular, and mineralogical composition in order to obtain information on the astronomical objects occurring in outer space.
A typical size distribution of dust grains is n(r) ∝ r −3.5, where r is the radius of the dust particle. [10] Assuming this, the projected grain surface area distribution is πr 2 n(r) ∝ r −1.5. This indicates that the smallest dust grains dominate this method of heating. [11] Photoionization