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NGC 6337, the Ghostly Cheerio or Cheerio Nebula, is a toroidal 
planetary nebula
A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
The term "planetary nebula" is a misnomer because they are unrelated to planets. The ...
in the constellation Scorpius
Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation whose recognition pred ...
. It appears as a ring-shaped (annular
Annulus (or anulus) or annular indicates a ring- or donut-shaped area or structure. It may refer to:
Human anatomy
* ''Anulus fibrosus disci intervertebralis'', spinal structure
* Annulus of Zinn, a.k.a. annular tendon or ''anulus tendineus com ...
) transparent nebula resembling a piece of the breakfast cereal Cheerios
Cheerios is a brand of cereal manufactured by General Mills in the United States and Canada, consisting of pulverized oats in the shape of a solid torus. In Europe, Cheerios is marketed by Cereal Partners under the Nestlé brand; in Austral ...
, hence the name. Filament and knots, and a faint shell surround the ring. Its magnitude is 11.90; its position in Scorpius is right ascension
Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the equinox (celestial coordinates), March equinox to the (hour circle of the) point in questio ...
17h 22m15.67s, declination
In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or ...
-38° 29' 01.73". The Ghostly Cheerio has a redshift
In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...
value of -0.000236.
There is convincing evidence that a binary nucleus exists at the center of the nebula, with masses of 0.6 and 0.3 M⊙, and a separation of ≤ 1.26 R⊙, indicating a probable common envelope
In astronomy, a common envelope (CE) is gas that contains a binary star system. The gas does not rotate at the same rate as the embedded binary system. A system with such a configuration is said to be in a common envelope phase or undergoing comm ...
phase. The Ghostly Cheerio's projected radial expansion is slow, averaging .
See also
*List of NGC objects (6001–7000)
This is a list of NGC objects 6001–7000 from the New General Catalogue (NGC). The astronomical catalogue is composed mainly of star clusters, nebulae, and galaxies. Other objects in the catalogue can be found in the other subpages of the list of ...
References
Scorpius 6337 Planetary nebulae {{nebula-stub