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Similar nebulae not illuminated by stars do not exhibit visible radiation, but may be detected as opaque clouds blocking light from luminous objects behind them; they are called dark nebulae. [ 25 ] Although these nebulae have different visibility at optical wavelengths, they are all bright sources of infrared emission, chiefly from dust within ...
In many emission nebulae, an entire cluster of young stars is contributing energy. [1] [2] Stars that are hotter than 25,000 K generally emit enough ionizing ultraviolet radiation (wavelength shorter than 91.2 nm) to cause the emission nebulae around them to be brighter than the reflection nebulae. [3]
The Zone of Avoidance (ZOA, ZoA), or Zone of Galactic Obscuration (ZGO), [1] [2] is the area of the sky that is obscured by the Milky Way. [ 3 ] The Zone of Avoidance was originally called the Zone of Few Nebulae in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of " nebulae " in John Herschel 's General ...
A typical planetary nebula is roughly one light year across, and consists of extremely rarefied gas, with a density generally from 100 to 10,000 particles per cm 3. [40] (The Earth's atmosphere, by comparison, contains 2.5 × 10 19 particles per cm 3.) Young planetary nebulae have the highest densities, sometimes as high as 10 6 particles per ...
GS-NDG-9422 is a nebular dominated galaxy in the constellation Fornax that was discovered by NASA’s James Webb Space Telescope. [ 1 ] [ 2 ] [ 3 ] Scientists assume that the galaxy's light comes mostly from superheated gas (more than 80 000 degrees Celsius).
In astronomy, Bok globules are isolated and relatively small dark nebulae containing dense cosmic dust and gas from which star formation may take place. Bok globules are found within H II regions, and typically have a mass of about two [1] to 50 solar masses contained within a region about a light year or so across (about 4.5 × 10 47 m 3). [2]
N44 is classified as an emission nebula because it contains large regions of ionized hydrogen. However, the three strongest emission lines in the nebula are singly ionized oxygen atoms, which emit at an ultraviolet wavelength of 372.7 nm , doubly-ionized oxygen atoms, which emit at a blue-green wavelength of 500.7 nm, and neutral hydrogen atoms ...
The cores range in mass from a fraction to several times that of the Sun and are called protostellar (protosolar) nebulae. [2] They possess diameters of 0.01–0.1 pc (2,000–20,000 AU) and a particle number density of roughly 10,000 to 100,000 cm −3. [a] [35] [37] The initial collapse of a solar-mass protostellar nebula takes around 100,000 ...