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Lyman alpha nebulae around quasars can have sizes between 15 kpc and 460 kpc. [1] Especially large Enormous Lyα nebula (ELAN) can have large sizes of ≳100 kpc. [2] Farina et al. 2019 table 5 has an extensive compilation of Lyman alpha nebulae around quasars. [1] For now this list contains only the largest ELANs, with sizes larger than 300 kpc.
Earth's air has a density of approximately 10 19 molecules per cubic centimeter; by contrast, the densest nebulae can have densities of 10 4 molecules per cubic centimeter. Many nebulae are visible due to fluorescence caused by embedded hot stars, while others are so diffused that they can be detected only with long exposures and special filters.
The nebula contains ions of extremely high ionization potential. [20] The helium hydride ion, thought to be the earliest molecule to have been formed in the Universe (about 100,000 years after the Big Bang), was detected in 2019 for the first time in space in NGC 7027. [21] [22] There is also evidence for the presence of nanodiamond in NGC 7027 ...
Box Nebula NGC 6445: 1786 4.5 11.2 Sagittarius: Eye of Sauron Nebula M 1-42: 10 14 Sagittarius
The Owl Nebula (also known as Messier 97, M97 or NGC 3587) is a planetary nebula approximately 2,030 light years away in the constellation Ursa Major. [2] Estimated to be about 8,000 years old, [ 6 ] it is approximately circular in cross-section with a faint internal structure.
The Omega Nebula is between 5,000 and 6,000 light-years from Earth and it spans some 15 light-years in diameter. The cloud of interstellar matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. [3] The total mass of the Omega Nebula is an estimated 800 solar masses. [4]
The structure in the nebula is among the most complex ever seen in planetary nebulae. The spectrum of Butterfly Nebula shows that its central star is one of the hottest stars known, with a surface temperature in excess of 250,000 degrees Celsius, implying that the star from which it formed must have been very large.
N44 is an emission nebula with superbubble structure located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way in the constellation Dorado. [ 3 ] [ 4 ] [ 5 ] Originally catalogued in Karl Henize 's "Catalogue of H-alpha emission stars and nebulae in the Magellanic Clouds" of 1956, it is approximately 1,000 light-years wide and ...