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The Ring Nebula (also catalogued as Messier 57, M57 and NGC 6720) is a planetary nebula in the northern constellation of Lyra. [4] C] Such a nebula is formed when a star, during the last stages of its evolution before becoming a white dwarf , expels a vast luminous envelope of ionized gas into the surrounding interstellar space .
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]
The Messier was an aerodynamically clean, low wing monoplane. Its metal-structured wings were built around single box spars, with a support structure designed and patented by Messier and covered with unstressed plywood. The plan was trapezoidal, strongly tapered from 1.80 m (5 ft 11 in) at the root to 0.45 m (1 ft 6 in) at the tip.
Although at almost exactly the same position as a known Seyfert galaxy, the slight offset combined with a lack of a radio counterpart makes the point-like source probably unrelated to the galaxy. Whether the feature is a pulsar wind nebula, and if so whether it is related to the Cygnus Loop, is still unknown for certain. [ 22 ]
In May 2011, Messier-Bugatti-Dowty was formed through the merger of three Safran subsidiaries: Messier-Dowty, Messier-Bugatti and Messier Services. [26] During 2014, the firm became the sole owner of French joint-venture maintenance company Hydrep after acquiring the other 50% share formerly held by Sabena Technics. [27]
The Shockley–Queisser limit, zoomed in near the region of peak efficiency. In a traditional solid-state semiconductor such as silicon, a solar cell is made from two doped crystals, one an n-type semiconductor, which has extra free electrons, and the other a p-type semiconductor, which is lacking free electrons, referred to as "holes."