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The Carina Nebula is an example of a diffuse nebula Most nebulae can be described as diffuse nebulae, which means that they are extended and contain no well-defined boundaries. [ 24 ] Diffuse nebulae can be divided into emission nebulae , reflection nebulae and dark nebulae .
Porous chondrite dust particle. 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]
A significant issue with standard candles is the recurring question of how standard they are. For example, all observations seem to indicate that Type Ia supernovae that are of known distance have the same brightness, corrected by the shape of the light curve. The basis for this closeness in brightness is discussed below; however, the ...
Veil Nebula: 3° Heart Nebula: 2.5° by 2.5° Westerhout 5: 2.3° by 1.25° Sh2-54: 2.3° Carina Nebula: 2° by 2° Note: brightest nebula in the night sky, 1.0 apparent magnitude (V) North America Nebula: 2° by 100 ′ Earth in the Moon's sky: 2° - 1°48 ′ [12] Appearing about three to four times larger than the Moon in Earth's sky The Sun ...
[1] [2] They are believed to be a common feature of the evolution of planetary nebulae, but can only be resolved in the nearest examples. [2] They are generally larger than the size of the Solar System (i.e. the orbit of Pluto ), with masses of around 0.00001 times the mass of the Sun , which is comparable to the mass of the Earth .
In 1922, Alexander Friedmann derived his Friedmann equations from Einstein field equations, showing that the universe might expand at a rate calculable by the equations. [24] The parameter used by Friedmann is known today as the scale factor and can be considered as a scale invariant form of the proportionality constant of Hubble's law.
The nebula's color depends on its chemical composition and degree of ionization. Due to the prevalence of hydrogen in interstellar gas, and its relatively low energy of ionization, many emission nebulae appear red due to strong emissions of the Balmer series. If more energy is available, other elements will be ionized, and green and blue ...
The defining criterion of a shock wave is that the bulk velocity of the plasma drops from "supersonic" to "subsonic", where the speed of sound c s is defined by = / where is the ratio of specific heats, is the pressure, and is the density of the plasma.