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The '''Witch Head nebula''' (NGC 1909, IC 2118) is a [[reflection nebula]] in the [[constellation]] of [[Eridanus]].<ref name=constellation-guide/> Named for its resemblance to the profile of a [[witch]], it is unusual for a reflection nebula in that it reflects the light of a single [[star]], the star [[Rigel]] (Beta Orionis) in [[Orion]]. The Witch Head nebula cannot be seen with the naked eye as it is too faint, but can be located with a [[telescope]] to be 2.6 degrees west of Rigel. In fact, it is so faint that it was discovered photographically in 1909 by Max Wolf.<ref name=constellation-guide/> The nebula has also appeared in works of [[science fiction]], notably the tv series ''Andromeda''.

The '''Witch Head nebula''' (NGC 1909, IC 2118) is a [[reflection nebula]] in the [[constellation]] of [[Eridanus]].<ref name=constellation-guide/> Named for its resemblance to the profile of a [[witch]], it is unusual for a reflection nebula in that it reflects the light of a single [[star]], the star [[Rigel]] (Beta Orionis) in [[Orion]]. The Witch Head nebula cannot be seen with the naked eye as it is too faint, but can be located with a [[telescope]] to be 2.6 degrees west of Rigel. In fact, it is so faint that it was discovered photographically in 1909 by Max Wolf.<ref name=constellation-guide/> The nebula has also appeared in works of [[science fiction]], notably the TV series ''Andromeda''.

==Properties and Structure==

==Properties and Structure==

Sources suggest the nebula is situated 800-1,000 [[light year]]s from [[Earth]].<ref name=apod>[https://apod.nasa.gov/apod/ap151030.html The Witch Head Nebula] from apod.nasa.gov</ref> This means its apparent dimensions of a couple of degrees mean is is roughly 50-70 light years across.<ref name=apod/> The nebula appears blue as it reflects the light of the [[supergiant|blue supergiant]] [[Rigel]]. The dust contained within the nebula scatters blue light more efficiently than red, enhancing this. This scattering is similar in nature to why the sky appears blue here on Earth.

Sources suggest the nebula is situated 800-1,000 [[light year]]s from [[Earth]].<ref name=apod>[https://apod.nasa.gov/apod/ap151030.html The Witch Head Nebula] from apod.nasa.gov</ref> This means its apparent dimensions of a couple of degrees mean is roughly 50-70 light years across.<ref name=apod/> The nebula appears blue as it reflects the light of the [[supergiant|blue supergiant]] [[Rigel]]. The dust contained within the nebula scatters blue light more efficiently than red, enhancing this. This scattering is similar in nature to why the sky appears blue here on Earth.

[[Radio waves|Radio observations]] of the nebula have shown that it contains [[carbon monoxide]].<ref name=constellation-guide/> Six [[star]]s have been observed in the nebula, mainly T-Tauri stars, through observations made in the [[infrared]] using [[NASA]]'s Wide-Field Infrared Survey Explorer.<ref>[https://www.sciencesource.com/archive/IC-2118--Witch-Head-Nebula-SS2585316.html IC 2118, Witch Head Nebula] from sciencesource.com</ref> These T-Tauri stars are a type of [[variable star]], that have a mass less that twice that of the [[Sun]] but a greater radius resulting in them being significantly brighter. The appearance of the nebula is likely due to strong [[stellar wind]]s produced by nearby luminous stars.<ref>[https://www.eso.org/public/unitedkingdom/images/witchhead-ch17-bardon-cc/ Witch Head Nebula] from eso.org</ref> One of the stars may possess a an orbiting "ring of gas and dust" and [[planet]]s.

[[Radio waves|Radio observations]] of the nebula have shown that it contains [[carbon monoxide]].<ref name=constellation-guide/> Six [[star]]s have been observed in the nebula, mainly T-Tauri stars, through observations made in the [[infrared]] using [[NASA]]'s Wide-Field Infrared Survey Explorer.<ref>[https://www.sciencesource.com/archive/IC-2118--Witch-Head-Nebula-SS2585316.html IC 2118, Witch Head Nebula] from sciencesource.com</ref> These T-Tauri stars are a type of [[variable star]], that have a mass less that twice that of the [[Sun]] but a greater radius resulting in them being significantly brighter. The appearance of the nebula is likely due to strong [[stellar wind]]s produced by nearby luminous stars.<ref>[https://www.eso.org/public/unitedkingdom/images/witchhead-ch17-bardon-cc/ Witch Head Nebula] from eso.org</ref> One of the stars may possess an orbiting "ring of gas and dust" and [[planet]]s.

==References==

==References==