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Little dumbbell nebula (view source)
Revision as of 16:30, January 28, 2018
, 16:30, January 28, 2018Created page with "{{Night Sky | image = | designation =Messier 76<br/>NGC 650/NGC 651 | rightascension =01<sup>h</sup> 42<sup>m</sup> 24<sup>s</sup>..."
{{Night Sky
| image =
| designation =[[Messier catalogue|Messier 76]]<br/>[[NGC]] 650/[[NGC]] 651
| rightascension =01<sup>h</sup> 42<sup>m</sup> 24<sup>s</sup><ref name=messier-objects>[http://www.messier-objects.com/messier-76-little-dumbbell-nebula/ Messier 76: Little Dumbbell nebula] from messier-objects.com</ref>
| declination =+51° 34′ 31″<ref name=messier-objects/>
| distance =2,500 ly<ref name=messier-objects/>
| constellation =Perseus
| type =Planetary nebula
| dimensions =2.7'x1.8'<ref name=messier-objects/>
| magnitude =Apparent Mag: +10.1<ref name=messier-objects/><br/>Absolute Mag: +0.7<ref>From definition of absolute magnitude, using apparent magnitude (+10.1) and distance (2,500 ly) given here.</ref>
| redshift =-0.000064<ref name=simbad>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=m76&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id M76] from simbad.u-strasbg.fr</ref>
| radvelocity =-19.1 km/s<ref name=simbad/>
| propmotion =
| parallax =
}}
The '''Little dumbbell nebula''' (M76, NGC 650/NGC 651) is a [[planetary nebula]] in the [[constellation]] of [[Perseus]].<ref name=messier-objects/> It has two designations in the [[New General Catalogue]] as it was originally thought to be two separate objects. The name arises from it great similarity to the [[Dumbbell nebula]], though it appears somewhat smaller in telescopes. One of the four planetary nebulae in Messier's catalogue, along with the [[Dumbbell nebula]], the [[Ring nebula]] and the [[Owl nebula]]. The nebula's small size on the night sky and its faintness makes it one of the most difficult [[Messier object]]s to observe. It is visible with binoculars, but is better seen with a telescope.
==History==
The Little dumbbell nebula was first observed by Pierre Méchain on September 5, 1780.<ref name=freestarcharts>[https://freestarcharts.com/messier-76 Messier 76] from freestarcharts.com</ref> [[Charles Messier]] added it to his [[Messier catalogue|catalogue]] the following month on October 21.<ref name=messier-objects/> Later in 1787, [[William Herschel]] conjectured that the nebula was in fact a double nebula and gave each component a different designation. Subsequently, this was repeated when John Dreyer compile the [[New General Catalogue]] in 1888, giving the two supposed nebulae the identifiers NGC 650 and NGC 651. William Huggins used spectroscopy to show the nebula is composed gas in 1866, containing Nebulium lines.<ref name=seds>[http://www.messier.seds.org/m/m076.html messier 76] from messier.seds.org</ref> Issac Roberts noted similarities to the [[Ring nebula]] in 1891 but it was not until 1918 that Heber Doust Curtis classified the nebula as a [[planetary nebula]].<ref name=freestarcharts/> Issac Roberts also showed that it was a single and not a double nebula.
==Properties and Structure==
Its apparent diameter of around 2 arcseconds corresponds to a physical diameter of 1.23 [[light year]]s.<ref name=messier-objects/> There is great disagreement in the distance to the nebula, some sources suggest it is 1,700 light years, others as much 15,000 light years.<ref name=seds/> The central ring of gas is expanding at around 42 km/s<ref name=seds/> A large but faint halo, with a size of 190 arcseconds, surrounds the nebula. Two stars are believed to be at the centre of the nebula, one with a [[star magnitude|magnitude]] of 15.9 and an estimated temperature of 60,000 K.<ref name=messier-objects/> The nebula is thought to have a temperature of some 88,400 K.<ref name=messier-objects/>
Unusually for a nebula, it is brighter visually (magnitude 10.1) than photographically (magnitude 12.2).<ref name=seds/> This is because much of the light emitted by the nebula is in green 5007 [[Angstrom]] forbidden line of doubly ionized oxygen, [O III], which our eyes are very sensitive to.
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]
[[Category:Messier Objects]]
| image =
| designation =[[Messier catalogue|Messier 76]]<br/>[[NGC]] 650/[[NGC]] 651
| rightascension =01<sup>h</sup> 42<sup>m</sup> 24<sup>s</sup><ref name=messier-objects>[http://www.messier-objects.com/messier-76-little-dumbbell-nebula/ Messier 76: Little Dumbbell nebula] from messier-objects.com</ref>
| declination =+51° 34′ 31″<ref name=messier-objects/>
| distance =2,500 ly<ref name=messier-objects/>
| constellation =Perseus
| type =Planetary nebula
| dimensions =2.7'x1.8'<ref name=messier-objects/>
| magnitude =Apparent Mag: +10.1<ref name=messier-objects/><br/>Absolute Mag: +0.7<ref>From definition of absolute magnitude, using apparent magnitude (+10.1) and distance (2,500 ly) given here.</ref>
| redshift =-0.000064<ref name=simbad>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=m76&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id M76] from simbad.u-strasbg.fr</ref>
| radvelocity =-19.1 km/s<ref name=simbad/>
| propmotion =
| parallax =
}}
The '''Little dumbbell nebula''' (M76, NGC 650/NGC 651) is a [[planetary nebula]] in the [[constellation]] of [[Perseus]].<ref name=messier-objects/> It has two designations in the [[New General Catalogue]] as it was originally thought to be two separate objects. The name arises from it great similarity to the [[Dumbbell nebula]], though it appears somewhat smaller in telescopes. One of the four planetary nebulae in Messier's catalogue, along with the [[Dumbbell nebula]], the [[Ring nebula]] and the [[Owl nebula]]. The nebula's small size on the night sky and its faintness makes it one of the most difficult [[Messier object]]s to observe. It is visible with binoculars, but is better seen with a telescope.
==History==
The Little dumbbell nebula was first observed by Pierre Méchain on September 5, 1780.<ref name=freestarcharts>[https://freestarcharts.com/messier-76 Messier 76] from freestarcharts.com</ref> [[Charles Messier]] added it to his [[Messier catalogue|catalogue]] the following month on October 21.<ref name=messier-objects/> Later in 1787, [[William Herschel]] conjectured that the nebula was in fact a double nebula and gave each component a different designation. Subsequently, this was repeated when John Dreyer compile the [[New General Catalogue]] in 1888, giving the two supposed nebulae the identifiers NGC 650 and NGC 651. William Huggins used spectroscopy to show the nebula is composed gas in 1866, containing Nebulium lines.<ref name=seds>[http://www.messier.seds.org/m/m076.html messier 76] from messier.seds.org</ref> Issac Roberts noted similarities to the [[Ring nebula]] in 1891 but it was not until 1918 that Heber Doust Curtis classified the nebula as a [[planetary nebula]].<ref name=freestarcharts/> Issac Roberts also showed that it was a single and not a double nebula.
==Properties and Structure==
Its apparent diameter of around 2 arcseconds corresponds to a physical diameter of 1.23 [[light year]]s.<ref name=messier-objects/> There is great disagreement in the distance to the nebula, some sources suggest it is 1,700 light years, others as much 15,000 light years.<ref name=seds/> The central ring of gas is expanding at around 42 km/s<ref name=seds/> A large but faint halo, with a size of 190 arcseconds, surrounds the nebula. Two stars are believed to be at the centre of the nebula, one with a [[star magnitude|magnitude]] of 15.9 and an estimated temperature of 60,000 K.<ref name=messier-objects/> The nebula is thought to have a temperature of some 88,400 K.<ref name=messier-objects/>
Unusually for a nebula, it is brighter visually (magnitude 10.1) than photographically (magnitude 12.2).<ref name=seds/> This is because much of the light emitted by the nebula is in green 5007 [[Angstrom]] forbidden line of doubly ionized oxygen, [O III], which our eyes are very sensitive to.
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]
[[Category:Messier Objects]]