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Created page with "{{Night Sky | image = | designation =NGC 2392<br/>Cadwell 39 | rightascension =07<sup>h</sup> 29<sup>m</sup> 10.7669<sup>s</sup><ref name=constellation-guid..."
{{Night Sky
| image =
| designation =[[NGC]] 2392<br/>Cadwell 39
| rightascension =07<sup>h</sup> 29<sup>m</sup> 10.7669<sup>s</sup><ref name=constellation-guide>[http://www.constellation-guide.com/eskimo-nebula-ngc-2392/ Eskimo Nebula – NGC 2392] from constellation-guide.com</ref>
| declination =+20° 54′ 42.488″<ref name=constellation-guide/>
| distance =≥2,870 ly<ref name=constellation-guide/>
| constellation =Gemini
| type =Planetary nebula
| dimensions =48x48 arcseconds
| magnitude =Apparent Mag: +10.1<ref name=constellation-guide/><br/>Absolute Mag: ≤+0.4<ref name=constellation-guide/>
| redshift =0.000281±0.000007<ref name=simbad>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC+2392&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id NGC 2393] from simbad.u-strasbg.fr</ref>
| radvelocity =82.2±2 km/s<ref name=simbad/>
| propmotion =RA: -3.97 mas/yr<ref name=simbad/><br/>Dec.: 1.59 mas/yr<ref name=simbad/>
| parallax =5.60±3.75<ref name=simbad/>
}}
The '''Eskimo nebula''' (NGC 2392, Cadwell 39) is a [[planetary nebula]] in the [[constellation]] of [[Gemini]], the Twins.<ref name=constellation-guide/> The nebula's similar appearance to a face surrounded by a fur-lined parka has lead to it being called the "Eskimo nebula" and sometimes the Clown Face nebula. The nebula cannot be seen with the naked eye but can just be made out with binoculars or a small telescope. Through larger telescopes, the central star can be made out and the nebula has a green appearance. The nebula was first observed on January 17, 1787 by [[William Herschel]].<ref name=freestarcharts>[https://freestarcharts.com/ngc-2392 NGC 2392] from freestarcharts.com</ref> He described it as a 9<sup>th</sup> [[star magnitude|magnitude]] [[star]] surrounded by equal nebulosity in all directions.
==Properties and Structure==
The exact distance to the nebula is unknown, but it is thought to be at least 2,870 [[light year]]s away.<ref name=constellation-guide/> This uncertainty in its distance means its apparent size of 48 x 48 arcseconds corresponds to a physical radius of at least 0.34 light years.<ref name=freestarcharts/> The nebula is approaching [[Earth]] at 82.2 km/s.<ref name=simbad/>
The nebula possesses a complex structure consisting of various shells and streamers of [[gas]] surrounding a central [[star]].<ref>[http://www.esa.int/Our_Activities/Space_Science/The_Eskimo_Nebula_NGC_2392 The Eskimo Nebula (NGC 2392)] from esa.int</ref> These are so complex that they are not fully understood.<ref name=nasa>[https://www.nasa.gov/multimedia/imagegallery/image_feature_762.html Eskimo Nebula] from nasa.gov</ref> Images from the [[Hubble Space Telescope]] have demonstrated that the inner structure is believed to have been formed by the outpouring of radiation from the central star pushing a bubble of gas outwards. The outer region contains extremely long filaments of material, some are around a light year long.<ref name=nasa/> The nebula also contains "cometary knots," also seen in other [[planetary nebulae]] such as the [[Helix nebula]] and [[Dumbbell nebula]].
A study performed using the [[Chandra|Chandra X-ray Observatory]] has observed higher than usual [[x-ray]] emission from the nebula.<ref name=chandra>[http://chandra.harvard.edu/photo/2013/ngc2392/ NGC 2392] from chandra.harvard.edu</ref> Two other nebulae that were investigated, the [[Spirograph nebula]] and NGC 6826, and both had lower x-ray emissions. It has been suggested these higher emissions are due to an unseen [[star]] orbiting the star that is visible, making it a [[binary star|binary system]].<ref name=chandra/> The interaction of the two stars would explain the additional x-ray radiation. In the other nebula, x-rays are only produced by shock fronts in the [[stellar wind]] created by the central stars in those nebulae.<ref name=chandra/>
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]
| image =
| designation =[[NGC]] 2392<br/>Cadwell 39
| rightascension =07<sup>h</sup> 29<sup>m</sup> 10.7669<sup>s</sup><ref name=constellation-guide>[http://www.constellation-guide.com/eskimo-nebula-ngc-2392/ Eskimo Nebula – NGC 2392] from constellation-guide.com</ref>
| declination =+20° 54′ 42.488″<ref name=constellation-guide/>
| distance =≥2,870 ly<ref name=constellation-guide/>
| constellation =Gemini
| type =Planetary nebula
| dimensions =48x48 arcseconds
| magnitude =Apparent Mag: +10.1<ref name=constellation-guide/><br/>Absolute Mag: ≤+0.4<ref name=constellation-guide/>
| redshift =0.000281±0.000007<ref name=simbad>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC+2392&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id NGC 2393] from simbad.u-strasbg.fr</ref>
| radvelocity =82.2±2 km/s<ref name=simbad/>
| propmotion =RA: -3.97 mas/yr<ref name=simbad/><br/>Dec.: 1.59 mas/yr<ref name=simbad/>
| parallax =5.60±3.75<ref name=simbad/>
}}
The '''Eskimo nebula''' (NGC 2392, Cadwell 39) is a [[planetary nebula]] in the [[constellation]] of [[Gemini]], the Twins.<ref name=constellation-guide/> The nebula's similar appearance to a face surrounded by a fur-lined parka has lead to it being called the "Eskimo nebula" and sometimes the Clown Face nebula. The nebula cannot be seen with the naked eye but can just be made out with binoculars or a small telescope. Through larger telescopes, the central star can be made out and the nebula has a green appearance. The nebula was first observed on January 17, 1787 by [[William Herschel]].<ref name=freestarcharts>[https://freestarcharts.com/ngc-2392 NGC 2392] from freestarcharts.com</ref> He described it as a 9<sup>th</sup> [[star magnitude|magnitude]] [[star]] surrounded by equal nebulosity in all directions.
==Properties and Structure==
The exact distance to the nebula is unknown, but it is thought to be at least 2,870 [[light year]]s away.<ref name=constellation-guide/> This uncertainty in its distance means its apparent size of 48 x 48 arcseconds corresponds to a physical radius of at least 0.34 light years.<ref name=freestarcharts/> The nebula is approaching [[Earth]] at 82.2 km/s.<ref name=simbad/>
The nebula possesses a complex structure consisting of various shells and streamers of [[gas]] surrounding a central [[star]].<ref>[http://www.esa.int/Our_Activities/Space_Science/The_Eskimo_Nebula_NGC_2392 The Eskimo Nebula (NGC 2392)] from esa.int</ref> These are so complex that they are not fully understood.<ref name=nasa>[https://www.nasa.gov/multimedia/imagegallery/image_feature_762.html Eskimo Nebula] from nasa.gov</ref> Images from the [[Hubble Space Telescope]] have demonstrated that the inner structure is believed to have been formed by the outpouring of radiation from the central star pushing a bubble of gas outwards. The outer region contains extremely long filaments of material, some are around a light year long.<ref name=nasa/> The nebula also contains "cometary knots," also seen in other [[planetary nebulae]] such as the [[Helix nebula]] and [[Dumbbell nebula]].
A study performed using the [[Chandra|Chandra X-ray Observatory]] has observed higher than usual [[x-ray]] emission from the nebula.<ref name=chandra>[http://chandra.harvard.edu/photo/2013/ngc2392/ NGC 2392] from chandra.harvard.edu</ref> Two other nebulae that were investigated, the [[Spirograph nebula]] and NGC 6826, and both had lower x-ray emissions. It has been suggested these higher emissions are due to an unseen [[star]] orbiting the star that is visible, making it a [[binary star|binary system]].<ref name=chandra/> The interaction of the two stars would explain the additional x-ray radiation. In the other nebula, x-rays are only produced by shock fronts in the [[stellar wind]] created by the central stars in those nebulae.<ref name=chandra/>
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]