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Interstellar medium Reference Libraries

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UV Astronomy
2004-10-19 04:45:43

UV Astronomy -- UV astronomy is the branch of astronomy and astrophysics which deals with objects visible in ultraviolet (UV) radiation. UV radiation ranges approximatively from 10nm (extreme UV) to 380nm (near UV). Ultraviolet line spectrum measurements are used to discern the chemical composition, densities, and temperatures of interstellar medium, and the temperature and composition...

Molecular Cloud
2004-10-19 04:45:41

Molecular Cloud -- Molecular clouds are interstellar nebulae that have a density and size sufficient to permit the formation of H2, molecular hydrogen. However, this molecule is difficult to detect, and the molecule most used to trace the H2 is CO (carbon monoxide). The ratio between CO luminosity and H2 mass is roughly constant, although there are reasons to doubt this assumption in...

Interstellar Cloud
2004-10-19 04:45:41

Interstellar Cloud -- Interstellar cloud is the generic name given to accumulations of gas and dust in our galaxy. Depending on the density, size and temperature of a given cloud, the hydrogen in it can be neutral (HI clouds) or molecular (molecular clouds). Chemical compositions Analysing the composition of interstellar clouds is achieved by studying electromagnetic radiation that we...

Heliopause
2004-10-19 04:45:41

Heliopause -- The heliopause is the boundary where our Sun's solar wind is stopped by the interstellar medium. The solar wind blows a "bubble" in the interstellar medium (the rareified hydrogen and helium gas that permeates the galaxy). The point where the solar wind's strength is no longer great enough to push back the interstellar medium is known as the heliopause, and is often considered...

Emission Nebula
2004-10-19 04:45:41

Emission Nebula -- In astronomy, emission nebulae are clouds of ionized gas, emitting light of various colors. The most common source for ionization are high-energy photons emitted from a nearby young, hot star. Usually, a young star will ionize part of the same cloud from which it was born. Only big, hot stars can release the amount of energy required to ionize a significant part of a...

Solar Wind
2004-10-19 04:45:41

Solar Wind -- Solar wind, a stream of particles (mostly high-energy protons ~ 500 Kev) that is continually ejected from the surface of the Sun. The composition of this plasma is identical to the Sun's corona, 73% hydrogen and 25% helium with the remainder as trace impurities, and is ionized. Near Earth, the velocity of the solar wind varies from 200km/s-889km/s. The average is 450 km/s....

Word of the Day
barghest
  • A goblin in English folklore, often appearing in the shape of a large dog and believed to portend imminent death or misfortune.
  • A ghost, wraith, hobgoblin, elf, or spirit.
The origin of 'barghest' is not known, but it may be from perhaps burh-ghest, town-ghost, or German Berg-geist (mountain spirit) or Bär-geist (bear-spirit).
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