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NGC 6445, also known as the Little Gem Nebula or Box Nebula, is a planetary nebula in the constellation Sagittarius. It was discovered by William Herschel on May 28, 1786. [ 6 ] The distance of NGC 6445 is estimated to be slightly more than 1,000 parsecs based on the parallax measured by Gaia , which was measured at 0.9740 ± 0.3151 mas.
The Necklace Nebula is a Strömgren sphere. It shows a dotted circle which gives its name. It shows a dotted circle which gives its name. In supernova remnant 1987A, the Strömgren shell is strangulated into an hourglass whose limbs are like three pearl necklaces.
The nebula is rich in carbon, and is a very interesting object for the study of carbon chemistry in dense molecular material exposed to strong ultraviolet radiation. [18] The spectrum of NGC 7027 contains fewer spectral lines from neutral molecules than is usual for planetary nebulae.
Atomic physics plays a key role in astrophysics as astronomers' only information about a particular object comes through the light that it emits, and this light arises through atomic transitions. Molecular astrophysics , developed into a rigorous field of investigation by theoretical astrochemist Alexander Dalgarno beginning in 1967, concerns ...
NGC 6905, also known as the Blue Flash Nebula, is a planetary nebula in the constellation Delphinus. It was discovered by William Herschel in 1784. The central star is 14.0 mag. The distance of the nebula, as with most planetary nebulae, is not well determined and estimates range between 1.7 and 2.6 kpc. [2]
A molecular cloud—sometimes called a stellar nursery if star formation is occurring within—is a type of interstellar cloud of which the density and size permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, H 2), and the formation of H II regions.
Enormous Lyα nebula (ELAN) Around the quasar UM287 at around z=2.3. Cosmic filament illuminated by the quasar. MAMMOTH-1: 1,441,000 ly (442,000 pc) [7] Enormous Lyα nebula (ELAN) The nebula is associated with the galaxy overdensity BOSS1441, [7] which is a protocluster at z=2.3. The nebula represents the circumgalactic medium. Its emission is ...
IC 11, Sh2-184, [3] Sharpless 184, [1] LBN 616, LBN 123.17-06.28, Pacman Nebula See also: Lists of nebulae NGC 281 , IC 11 or Sh2-184 is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way 's Perseus Spiral Arm .