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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.
The number of nebulae was then greatly increased by the efforts of William Herschel and his sister, Caroline Herschel. Their Catalogue of One Thousand New Nebulae and Clusters of Stars [16] was published in 1786. A second catalog of a thousand was published in 1789, and the third and final catalog of 510 appeared in 1802.
The following articles contain lists of nebulae: List of dark nebulae; List of diffuse nebulae; List of largest nebulae; List of planetary nebulae;
The Eagle Nebula is part of a diffuse emission nebula, or H II region, which is catalogued as IC 4703. This region of active current star formation is about 5700 light-years distant. A spire of gas that can be seen coming off the nebula in the northeastern part is approximately 9.5 light-years or about 90 trillion kilometers long. [6]
The M42 nebula is estimated to be 25 light-years across (so its apparent size from Earth is approximately 1 degree). It has a mass of about 2,000 times that of the Sun. Older texts frequently refer to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula. [7]
The nebula is arranged in three concentric shells, with the outermost shell being about 20–30% larger than the inner shell. [7] The owl-like appearance of the nebula is the result of an inner shell that is not circularly symmetric, but instead forms a barrel-like structure aligned at an angle of 45° to the line of sight.
It is sometimes compared to the more extensively studied Butterfly Nebula (M 2-9), and it is quite likely that both have a similar evolutionary history. They both have point-like bright nuclei, are narrow-waisted bipolar nebulae, and share surprisingly similar spatially dependent spectra. Because of their similarity, their differences are ...
A large pelican can attain a wingspan of 3.6 m (12 ft), second only to the great albatrosses among all living birds. [ 119 ] The largest of the cormorants is the flightless cormorant of the Galapagos Islands ( Nannopterum harrisi ), at up to 5 kg (11 lb) and 1 m (3.3 ft), although large races in the great cormorant ( Phalacrocorax carbo ) can ...