View source for Astronomy:NGC 6751

{{Short description|Planetary nebula in the constellation Aquila}}
{{ Planetary nebula
| image = [[Image:NGC6751.jpg|250px|]] 
|caption=A [[Astronomy:Hubble Space Telescope|Hubble Space Telescope]] (HST) image of NGC 6751's inner bubble<br/>Credit: HST/[[Organization:NASA|NASA]]/ESA.
| name = [[Astronomy:New General Catalogue|NGC]] 6751
| type = Planetary
| epoch = J2000.0
| ra = {{RA|19|05|55.6}}<ref name="simbad">{{cite simbad
  | title=NGC 6751
  | access-date=2007-04-27}}</ref>
| dec = {{DEC|-05|59|32.9}}<ref name="simbad" />
| dist_ly = 6,500
| dist_pc = 2,000<ref name=Clark/>
| appmag_v = 11.9<ref name="NGC/IC Project">{{cite web
  | title=NGC/IC Project
  | url=http://www.ngcicproject.org/dss/dss_ngc.asp
  | access-date=2010-01-01
  | archive-url=https://web.archive.org/web/20091201033412/http://www.ngcicproject.org/dss/dss_ngc.asp
  | archive-date=2009-12-01
  | url-status=dead
  }}</ref>
| size_v =  0.43{{prime}}
| constellation  = [[Astronomy:Aquila (constellation)|Aquila]]
| radius_ly = 0.4 
| absmag_v = 0.4 
| names = Glowing Eye Nebula, [[Astronomy:Guide Star Catalog|GSC]] 05140-03497, PK 029-05 1, PN Th 1-J, CSI-06-19031, HD 177656, PMN J1905-0559, PN Sa 2-382, EM* CDS 1043, HuLo 1, PN ARO 101, PN G029.2-05.9, GCRV 11549, [[Astronomy:IRAS|IRAS]] 19032-0604, PN VV' 477, SCM 227, GSC2 S3002210353, [[Astronomy:2MASX|2MASX]] J19055556-0559327, PN VV 219, [[Astronomy:USNO CCD Astrograph Catalog|UCAC2]] 29903231
}}
'''NGC 6751''', also known as the '''Glowing Eye Nebula''',<ref name=Clark/> is a [[Astronomy:Planetary nebula|planetary nebula]] in the [[Astronomy:Constellation|constellation]] [[Astronomy:Aquila (constellation)|Aquila]]. It is estimated to be about 6,500 [[Astronomy:Light-year|light-year]]s (2.0 kilo[[Astronomy:Parsec|parsec]]s) away.<ref name=Clark>{{cite journal|doi=10.1088/0004-637X/722/2/1260|bibcode=2010ApJ...722.1260C|title=Shaping the Glowing Eye Planetary Nebula, NGC 6751|year=2010|last1=Clark|first1=D. M.|last2=García-Díaz|first2=Ma. T.|last3=López|first3=J. A.|last4=Steffen|first4=W. G.|last5=Richer|first5=M. G.|journal=The Astrophysical Journal|volume=722|issue=2|pages=1260–1268|s2cid=122344448 }}</ref>

NGC 6751 was discovered by the astronomer [[Biography:Albert Marth|Albert Marth]] on 20 July 1863.<ref name=cseligman>{{cite web|url=http://cseligman.com/text/atlas/ngc67a.htm#6751|title=New General Catalogue objects: NGC 6750 - 6799|author=Seligman, Courtney|website=cseligman.com|access-date=2021-04-12}}</ref> [[Biography:John Louis Emil Dreyer|John Louis Emil Dreyer]], the compiler of the [[Astronomy:New General Catalogue|New General Catalogue]], described the object as "pretty bright, small".<ref name=cseligman/> The object was assigned a duplicate designation, NGC 6748.<ref name=cseligman/><ref name=Corwin>{{Cite web|url=http://haroldcorwin.net/ngcic/ngcnotes.all|title=Notes on the NGC objects, particularly those missing, misidentified, or otherwise unusual (ngcnotes.all).|website=Historically-aware NGC/IC Positions and Notes|access-date=2019-08-10|author=Corwin, Harold}}</ref>

The nebula was the subject of the winning picture in the 2009 Gemini School Astronomy Contest, in which Australian high school students competed to select an astronomical target to be imaged by Gemini.

NGC 6751 is an easy telescopic target for [[Astronomy:Deep-sky object|deep-sky]] observers because its location is immediately southeast of the extremely red-colored cool [[Astronomy:Carbon star|carbon star]] [[Astronomy:V Aquilae|V Aquilae]].

==Properties==
NGC 6751, like all [[Astronomy:Planetary nebula|planetary nebula]]e was formed when a dying [[Astronomy:Star|star]] threw off its outer layers of gas several thousand years ago. It is estimated to be around 0.8 light-years in diameter.<ref>{{cite web|url=https://hubblesite.org/image/956/gallery|title=The Glowing Eye of Planetary Nebula NGC 6751|date=2000-04-06|website=HubbleSite|access-date=2021-04-12}}</ref>

NGC 6751 has a complex [[Astronomy:Bipolar nebula|bipolar]] structure. There is a bright, inner bubble (shown in the photo), as well as two fainter halos. (The outer halo, with a radius of 50{{pprime}} is extremely faint and is broken, while the inner halo with a radius of 27{{pprime}} is roughly spherical).<ref name=Clark/> On both the west and east sides of the inner shell, knots can be seen that are surrounded by faint "lobes".<ref name=Clark/> These lobes are actually a ring, and the eastern side is nearer than the western side.<ref name=Clark/> As a whole, the system is approaching the Solar System with a heliocentric [[Astronomy:Radial velocity|radial velocity]] of &minus;31.7 km/s.<ref name=Clark/>

The central star of the nebula has a similar spectrum to a [[Astronomy:Wolf–Rayet star|Wolf–Rayet star]] (spectral type [WC4]),<ref name=simbad/> and has an [[Astronomy:Effective temperature|effective temperature]] of about 140,000 K and a radius of about {{solar radius|0.13}}. It is losing mass at a rate of {{solar mass|{{val|1e-6}}}} per year, and its surface composition is mostly [[Chemistry:Helium|helium]] and [[Chemistry:Carbon|carbon]].<ref name=Clark/>

The winning image of the 2009 Gemini Astronomy Contest shows a nebula at the top left of NGC 6751.<ref name=Gemini>{{cite web|url=http://www.gemini.edu/node/11329|title=Australian Student's Image Revealed|date=2009-07-21|publisher=Gemini Observatory|access-date=2021-04-12}}</ref> This 80 x 40 arcsec nebula was discovered in 1990 by Hua & Louise at the Newton focus of the Foucault telescope, 120cm in diameter at Observatoire de Haute Provence (O.H.P.) Saint Michel l'Observatoire.<ref>{{cite journal |bibcode=1990A&A...235..403H |title=The emission line nebulosity near the planetary nebula NGC 6751 |last1=Hua |first1=C. T. |last2=Louise |first2=R. |journal=Astronomy and Astrophysics |date=1990 |volume=235 |page=403 }}</ref>

==See also==
* [[Astronomy:List of planetary nebulae|List of planetary nebulae]]

==References==
{{reflist}}

==External links==
* {{APOD |date=16 April 2005 |title=Celebrating Hubble With NGC 6751}}
* [http://spider.seds.org/ngc/ngc.cgi?6751 NGC 6751] seds.org
* {{APOD |date=13 March 2013 |title=NGC 6751: The Glowing Eye Nebula}}


{{Stars of Aquila}}

{{DEFAULTSORT:NGC 6751}}
[[Category:Planetary nebulae]]
[[Category:NGC objects|6751]]
[[Category:Aquila (constellation)]]
[[Category:Henry Draper Catalogue objects|177656]]

{{Sourceattribution|NGC 6751}}