NGC 6751, also known as the Glowing Eye Nebula, is a planetary nebula in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Aquila. It is estimated to be about 6,500

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s (2.0 kilo parsecs) away. NGC 6751 was discovered by the astronomer Albert Marth on 20 July 1863. John Louis Emil Dreyer, the compiler of the

New General Catalogue The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and ...

, described the object as "pretty bright, small". The object was assigned a duplicate designation, NGC 6748. 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 Gemini may refer to: Space * Gemini (constellation), one of the constellations of the zodiac ** Gemini in Chinese astronomy * Project Gemini, the second U.S. crewed spaceflight program * Gemini Observatory, consisting of telescopes in the Northern ...

. NGC 6751 is an easy telescopic target for deep-sky observers because its location is immediately southeast of the extremely red-colored cool

carbon star A carbon star (C-type star) is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monoxide, which consumes mos ...

V Aquilae.

Properties

NGC 6751, like all planetary nebulae was formed when a dying

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

threw off its outer layers of gas several thousand years ago. It is estimated to be around 0.8 light-years in diameter. NGC 6751 has a complex

bipolar Bipolar may refer to: Astronomy * Bipolar nebula, a distinctive nebular formation * Bipolar outflow, two continuous flows of gas from the poles of a star Mathematics * Bipolar coordinates, a two-dimensional orthogonal coordinate system * 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 is extremely faint and is broken, while the inner halo with a radius of 27 is roughly spherical). On both the west and east sides of the inner shell, knots can be seen that are surrounded by faint "lobes". These lobes are actually a ring, and the eastern side is nearer than the western side. As a whole, the system is approaching the Solar System with a heliocentric

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

of −31.7 km/s. The central star of the nebula has a similar spectrum to a

Wolf–Rayet star Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface ...

(spectral type C4, and has an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of about 140,000 K and a radius of about . It is losing mass at a rate of per year, and its surface composition is mostly

helium Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. ...

and

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

. The winning image of the 2009 Gemini Astronomy Contest shows a nebula at the top left of NGC 6751. 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 The Haute-Provence Observatory (OHP, french: Observatoire de Haute-Provence) is an astronomical observatory in the southeast of France, about 90 km east of Avignon and 100 km north of Marseille. It was established in 1937 as a nationa ...

(O.H.P.) Saint Michel l'Observatoire.

References

External links

* *
NGC 6751
seds.org * {{DEFAULTSORT:NGC 6751 Planetary nebulae 6751 Aquila (constellation) 177656

Properties

See also

References

External links