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Created page with "{{Night Sky | image = | designation =NGC 7635<br/>Cadwell 11 | rightascension =23<sup>h</sup> 20<sup>m</sup> 48.3<sup>s</sup><ref name=constellation-guide>[..."
{{Night Sky
| image =
| designation =[[NGC]] 7635<br/>Cadwell 11
| rightascension =23<sup>h</sup> 20<sup>m</sup> 48.3<sup>s</sup><ref name=constellation-guide>[http://www.constellation-guide.com/bubble-nebula-ngc-7635/ Bubble Nebula – NGC 7635] from constellation-guide.com</ref>
| declination =+61° 12′ 06″<ref name=constellation-guide/>
| distance =7,100-11,000 ly<ref name=constellation-guide/>
| constellation =Cassiopeia
| type =Emission nebula
| dimensions =15'x10' <ref name=constellation-guide/>
| magnitude =Apparent Mag: +10<ref name=constellation-guide/><br/>Absoulte Mag: -2<ref>From definition of absolute magnitude, using apparent magnitude given here and a midpoint distance of (7,000+11,000)/2=9,000 light years.</ref>
| redshift =
| radvelocity =
| propmotion =
| parallax =
}}
The '''Bubble nebula''' (NGC 7635, Cadwell 11, Sharpless 162) is an [[emission nebula]] in the [[constellation]] of [[Cassiopeia]].<ref name=freestarcharts>[https://freestarcharts.com/ngc-7635 NGC 7635] from freestarcharts.com</ref> Discovered by [[William Herschel]], the nebula has a distinctive spherical shape, making it look like a bubble of gas and giving it the name, the "Bubble nebula." Best observed in late summer/early autumn, the Bubble nebula can just about be seen with small telescopes but is best observed with larger telescopes.<ref name=freestarcharts/> To celebrate the 26<sup>th</sup> anniversary of the launch of the [[Hubble Space Telescope]], the HST took a spectacular photo of the nebula in 2016.<ref name=nasa>[https://www.nasa.gov/feature/goddard/2016/hubble-sees-a-star-inflating-a-giant-bubble Hubble sees a star inflating a giant bubble] from nasa.gov</ref>
==Properties and Structure==
The nebula's great distance means it has a physical size of around 10 [[light year]]s.<ref name=constellation-guide/> The nebula's distinctive shape comes from its central [[star]] which emits vast amounts of radiation. This produces a large stellar wind which "blows" [[gas]] and [[dust]] away from the star. The radiation the star emits is enough to ionize the gas surrounding the star and make it glow as an [[emission nebula]]. The stellar wind is nearly uniform across the star resulting in an almost spherical shell of gas enclosing the star. A cold region of gas on one side of the star means the nebula is not completely symmetric.<ref name=nasa/> This along with the stars motion means it is not at the centre of the nebula, but slightly off centre.
The central star, with designations SAO 20575 and BD+60 2522, belongs to a class of stars known as [[Wolf-Rayet star]]s and has a spectral type of O6.5.<ref name=constellation-guide/> It has an apparent magnitude of +8.71 and a mass around 45 times that of the [[Sun]].<ref name=constellation-guide/><ref name=nasa/> This corresponds to an absolute magnitude of -5.5 making the star around 398,000 times more luminous than the Sun.<ref name=constellation-guide/> The star itself is approaching us at around 26 km/s and has a [[parallax]] of 0.41 milliarcseconds.<ref>The star [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=BD%2B60+2522&submit=submit+id BD+60 2522] from simbad.u-strasbg.fr</ref> The star has a [[radius]] or some 15 solar radii and is extremely hot with a surface temperature of 37,500 K.
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]
| image =
| designation =[[NGC]] 7635<br/>Cadwell 11
| rightascension =23<sup>h</sup> 20<sup>m</sup> 48.3<sup>s</sup><ref name=constellation-guide>[http://www.constellation-guide.com/bubble-nebula-ngc-7635/ Bubble Nebula – NGC 7635] from constellation-guide.com</ref>
| declination =+61° 12′ 06″<ref name=constellation-guide/>
| distance =7,100-11,000 ly<ref name=constellation-guide/>
| constellation =Cassiopeia
| type =Emission nebula
| dimensions =15'x10' <ref name=constellation-guide/>
| magnitude =Apparent Mag: +10<ref name=constellation-guide/><br/>Absoulte Mag: -2<ref>From definition of absolute magnitude, using apparent magnitude given here and a midpoint distance of (7,000+11,000)/2=9,000 light years.</ref>
| redshift =
| radvelocity =
| propmotion =
| parallax =
}}
The '''Bubble nebula''' (NGC 7635, Cadwell 11, Sharpless 162) is an [[emission nebula]] in the [[constellation]] of [[Cassiopeia]].<ref name=freestarcharts>[https://freestarcharts.com/ngc-7635 NGC 7635] from freestarcharts.com</ref> Discovered by [[William Herschel]], the nebula has a distinctive spherical shape, making it look like a bubble of gas and giving it the name, the "Bubble nebula." Best observed in late summer/early autumn, the Bubble nebula can just about be seen with small telescopes but is best observed with larger telescopes.<ref name=freestarcharts/> To celebrate the 26<sup>th</sup> anniversary of the launch of the [[Hubble Space Telescope]], the HST took a spectacular photo of the nebula in 2016.<ref name=nasa>[https://www.nasa.gov/feature/goddard/2016/hubble-sees-a-star-inflating-a-giant-bubble Hubble sees a star inflating a giant bubble] from nasa.gov</ref>
==Properties and Structure==
The nebula's great distance means it has a physical size of around 10 [[light year]]s.<ref name=constellation-guide/> The nebula's distinctive shape comes from its central [[star]] which emits vast amounts of radiation. This produces a large stellar wind which "blows" [[gas]] and [[dust]] away from the star. The radiation the star emits is enough to ionize the gas surrounding the star and make it glow as an [[emission nebula]]. The stellar wind is nearly uniform across the star resulting in an almost spherical shell of gas enclosing the star. A cold region of gas on one side of the star means the nebula is not completely symmetric.<ref name=nasa/> This along with the stars motion means it is not at the centre of the nebula, but slightly off centre.
The central star, with designations SAO 20575 and BD+60 2522, belongs to a class of stars known as [[Wolf-Rayet star]]s and has a spectral type of O6.5.<ref name=constellation-guide/> It has an apparent magnitude of +8.71 and a mass around 45 times that of the [[Sun]].<ref name=constellation-guide/><ref name=nasa/> This corresponds to an absolute magnitude of -5.5 making the star around 398,000 times more luminous than the Sun.<ref name=constellation-guide/> The star itself is approaching us at around 26 km/s and has a [[parallax]] of 0.41 milliarcseconds.<ref>The star [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=BD%2B60+2522&submit=submit+id BD+60 2522] from simbad.u-strasbg.fr</ref> The star has a [[radius]] or some 15 solar radii and is extremely hot with a surface temperature of 37,500 K.
==References==
{{reflist}}
{{Nebulae}}
[[Category:Astronomy]]
[[Category:Nebulae]]