Cosmic dust

A kind of solid dust composed of many fine particles

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Cosmic Dust is a solid state composed of many small particles dust , from Big Bang Since then, they have scattered in Haohan universe in The composition of cosmic dust includes silicate 、 carbon etc. element as well as water content , partly from comet 、 asteroid The size of a few microns to several hundred microns is produced by the disintegration of an isostar.

Chinese name: Cosmic dust
Foreign name: Cosmic Dust
Discipline: astronomy

Definition: A kind of solid dust
Size: A few microns to hundreds of microns
See publications: Geology Terms, Science Press
Time of publication: 1993^[4]

catalog

definition

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People constantly find dust particles from outside the earth on the surface of the earth, and collect and study them systematically. Generally, we call these solid particles from outside the earth cosmic dust. In fact, they are mainly interplanetary dust, comet tail material and Micrometeorite 。 Its size is several micron To hundreds of microns.^[1]

Cosmic dust versus one celestial bodies The birth of a star also has an impact. For example, the cosmic dust generated after the collapse of a star may collide with a forming star after a long cosmic journey, and then become a new star again. stay solar system Medium, Jupiter 、 Saturn 、 Uranus 、 Neptune etc. planet Of halo That is, when the planet was initially formed, the fragmented cosmic dust failed to melt into the main body of the planet, but could not get rid of the planet Universal gravitation And produce broken materials around the planet.

nature

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Every day, hundreds of tons of cosmic dust scatter on the earth's surface. Cosmic dust samples have been found in deep-sea sediments, mountain snow, ancient polar ice and tens of kilometers high. From the appearance, most of them are spherical. Some of them have rough surfaces with ablation marks, and some are smooth, crystal clear and colorful. Different colors indicate that element abundance Is different. Black pellets mostly contain Fe ， Mn ， Co Etc. The element abundance and radio isotope The relative abundance of can be measured to determine whether they come from space. Radioisotopes produced by cosmic rays have been found in cosmic dust

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Etc. From the abundance of these radioisotopes, it can be inferred that the age of cosmic dust is similar to that of the solar system. Cosmic dust floats in space for a long time, in which there must be a lot of high-energy nuclear interaction phenomena of extreme stripe fall (extremely low temperature, extremely high vacuum, etc.), and because it is falling into the earth atmosphere The rear movement speed is very slow, it will not burn like a meteor, and it may save more original information. Therefore, cosmic dust is an important natural sample for studying the long-term changes, production, propagation and composition of cosmic rays. It is the division that people have never been able to get Meteorite ， Moonstone The third kind of cosmic matter.^[1]

application

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Cosmic dust absorbs and scatters blue light and Ultraviolet radiation It makes the passing starlight appear red and is discovered - this is the same as the blue light scattered by the dust in the earth's atmosphere and passes through the red light, forming a magnificent sunset glow The situation is the same.

The retention time of cosmic dust in the space is relatively short, about 10000 to 100000 years. Cosmic dust can penetrate the earth's atmosphere without being ablated. The amount of cosmic dust that settles to the earth's surface every year is about 10000~100000 ton 。 Cosmic dust preserves its original cosmic information, which is a research solar system Chemical composition and an ideal sample to speculate on the origin of the solar system. Therefore, people have always attached importance to the collection of dust particles planet International space collection can be conducted in stratosphere of use rocket 、 balloon It can also be collected from different types of sediments of different geological ages on the surface, such as Deep-sea sediment 、 manganese nodule , unconsolidated sediments and consolidated rocks on land polar region and glacier Ice and snow samples, etc. Habitually Meteorite The fine particles generated by ablation when entering the earth's atmosphere are called cosmic dust.^[2]

constitute

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Interstellar reddening change fixed star This is a color that must be taken into account in many astronomical observations. In our Galaxy Internal, due to the presence of interstellar absorption For every 1000 seconds of starlight propagation, the brightness of the star decreases by about 1 magnitude.

Spectroscopic studies show that most interstellar dust particles are composed of graphite and silicate The outer layer may be frozen water or ammonia 。 Or solid state carbon dioxide 。 Dust particles are probably Cold star The material from the air stream accounts for about 2% of the total mass of the interstellar cloud, and the total mass of dust particles in the entire galactic disk is 200 million times that of the sun.

Interstellar Bituminous coal And ammonia particles provide a surface for chemical reaction to produce complex molecules. Sir Fred Hoyle and Chandra Wickramasinger think it is possible to create organisms molecule This speculation is due to the rediscovery of a amino acid (glycine).

There are no dust particles between stars, but there must be gas Intergalactic matter , and possibly dark substance 。

Research

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March 20, 2019, Japan Nagoya University The research team of^[3] 。

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