Necklace Nebula
Encyclopedia
The Necklace Nebula is a planetary nebula
located about 15,000 light-years away in the northern constellation Sagitta
. It was discovered in 2005 from the Isaac Newton Telescope Photometric H-alpha Survey
(IPHAS), a ground-based H-alpha
planetary nebula study of the North Galactic Plane.
The Necklace Nebula is the exploded aftermath of a giant star that came too close to its Sun-like binary companion. The two stars that produced the Necklace Nebula are in a relatively small orbit about each other. They have a period of 1.2 days and a separation on the order of 5 times the radius of the Sun.
About 10,000 years ago one of the aging stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate.
The bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force
, most of the gas escaped along the star’s equator
, producing a ring. The embedded bright knots are dense gas clumps in the ring.
Planetary nebula
A planetary nebula is an emission nebula consisting of an expanding glowing shell of ionized gas ejected during the asymptotic giant branch phase of certain types of stars late in their life...
located about 15,000 light-years away in the northern constellation Sagitta
Sagitta
Sagitta is a constellation. Its name is Latin for "arrow", and it should not be confused with the larger constellation Sagittarius, the archer. Although ancient, it is insignificant, for it has no star brighter than the 4th magnitude and is the third smallest of all constellations...
. It was discovered in 2005 from the Isaac Newton Telescope Photometric H-alpha Survey
The INT Photometric H-Alpha Survey
The INT Photometric H-Alpha Survey is an astronomical survey of the northern plane of our Galaxy, the Milky Way, as visible from the Isaac Newton Telescope in the Canary Islands, Spain. The survey uses two broad-band filters and a narrow H-alpha filter to obtain deep images of nebulae in our...
(IPHAS), a ground-based H-alpha
H-alpha
H-alpha is a specific red visible spectral line created by hydrogen with a wavelength of 656.28 nm, which occurs when a hydrogen electron falls from its third to second lowest energy level...
planetary nebula study of the North Galactic Plane.
The Necklace Nebula is the exploded aftermath of a giant star that came too close to its Sun-like binary companion. The two stars that produced the Necklace Nebula are in a relatively small orbit about each other. They have a period of 1.2 days and a separation on the order of 5 times the radius of the Sun.
About 10,000 years ago one of the aging stars ballooned to the point where it engulfed its companion star. The smaller star continued orbiting inside its larger companion, increasing the giant’s rotation rate.
The bloated companion star spun so fast that a large part of its gaseous envelope expanded into space. Due to centrifugal force
Centrifugal force
Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...
, most of the gas escaped along the star’s equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
, producing a ring. The embedded bright knots are dense gas clumps in the ring.