Contrary to their name, these nebulae have nothing to do with planets. A planetary nebula is created when a star in the last stage of its life puffs off its outer atmosphere. The nebula usually looks like a donut, sometimes with the small, hot, rapidly evolving star visible in the center. The Ring Nebula (M 57) in the constellation Lyra is an example. See also

slowly expanding envelope of gas surrounding a small, hot central star.

The last gasp of a dying star, a planetary nebula consists of the outer layers of a star. These layers glow brilliantly from the hot ultraviolet radiation from the stellar core in the middle.

A nebula formed from by a shell of gas which was ejected from a certain kind of extremely hot star. As the giant star explodes, the core of the star is exposed. Planetary nebulae have nothing to do with planets.

A shell of glowing gas surrounding a star that was ejected from that star.

A cloud of glowing, ionized gas, usually taking the form of a hollow sphere or shell, ejected by a star in the late stages of its evolution.

A gaseous shell surrounding a hot central star. They often look like planets, but they are much hotter: the surface temperature is anywhere from 30,000 to 150,000 degrees Celsius.

Near the end of their lives, most stars slough off their outer layers, puffing out shells of gas that can grow to several light years in width. These are planetary nebula, named because early astronomers mistook them for distant planets. You can find more information at The Columbia Encyclopedia. Be sure to check out some spectacular Hubble Space Telescope photos of nebulae.

An expanding ring of gas around a star. | Back to Student Center

final mass-loss stage for a dying low-mass star in which the outer layers are ejected during the core's collapse to form a white dwarf.

type of emission nebula containing an expanding shell of gas surrounding very hot stars in a late stage of stellar evolution. Shapes include ring-like or circular structures, dumbbell-like and irregular. Planetary nebulae are of the emission type. Planetary nebulae are often typed by appearance ( Vorontsov-Velyaminov System): (Stellar Image); (Smooth disk with , brighter toward center; , uniform brightness; , traces of a ring structure); (Irregular disk with , very irregular brightness distribution; , traces of ring structure); (Ring structure); (Irregular form, similar to a diffuse nebula); (Anomalous form). More complex structures are designated as , "4+2" (ring and disk), "4+4" (two rings), and "3a+2" (irregular disk with irreg. brightness distribution plus smooth disk).

A shell of gas ejected from and expanding around a star usually seen near the end of the star's life.

a nebula that was once thought to be a star with its planets but is now thought to be a very hot star surrounded by an expanding envelope of ionized gases that emit a fluorescent glow because of intense radiation from the star

a doughnut-shaped ring of gas, nearly half a light year in diameter

a glowing gaseous shell thrown off

a nebula formed from by a shell of gas which was ejected from a certain kind of extremely hot star (a red giant or supergiant)

an object with a small dense core (central blue-white star) surrounded by an extended shell (or shells) of glowing matter

a series of glowing shells of gas around the remains of the star

a shell of gas that has been shed by a star late in its lifetime

a shell of material ejected from a dying star

a spherical shell of gas surrounding a hot star, which provides the energy for its light emissions

a (usually) spherical shell of gas (no, not a "ring") that is ejected from a star that has violently "shed" its outer layers of gas

see nebula

An expanding shell of gas ejected by a red giant star late in its life. (The term has nothing to do with planets.)

A planetary nebula is the nebula formed in the AGB stage of a star's life when it ejects its outer layers of gas. The exposed inner region of the star left behind is initially so hot that the intense ultraviolet radiation it emits ionises the expanding, ejected shell. This results in the cloud glowing, similar to an emission nebula. Such objects are called planetary nebulae after their initial description by Herschel in the 18th century. Through small telescopes they appear as faint discs, like a dim planet though they are not related. Planetary nebulae typically contain 0.1 - 0.2 solar masses at densities equivalent to a vacuum on Earth. Spectacular images by modern telescopes including the HST reveal a wide range of shapes that pose interesting problems for theorists to explain.

a ring of dust and gas blown off a red giant star after it undergoes an explosion.

The gaseous outer layers of a star that have been ejected into space as the star collapses into a white dwarf. The ultraviolet radiation from the white dwarf causes the gas to fluoresce.

A dying star with a shell of gas surrounding an exposed core. Ultraviolet radiation from the core causes the surrounding gas to fluoresce and glow. Eventually this outer shell will expand and dissipate, leaving the core completely exposed as a white dwarf. The Ring nebula, M57, in Lyra is the most observed planetary nebula.

A luminous cloud of gas expelled by an aging star that has become unstable. The name comes from a nebula's superficial resemblance to the faint planets Uranus and Neptune as seen through a small telescope. The Ring Nebula M57 in Lyra is a familiar example.

An expanding envelope of gas surrounding a hot white dwarf. It is formed at the end of a giant star's life when the core contracts ejecting the outer atmosphere of the star creating both the white dwarf and the nebula. The intense radiation from the central white dwarf makes the nebula glow. Planetary nebulae disperse within 50 000 years. They are called planetary nebulae because to early astronomers they looked a bit like planets.

The ejected envelope of a red giant star, spread over a volume roughly the size of our solar system, with a hot central star that is in the process of becoming a white dwarf star. [More Info: Field Guide

A shell of gas surrounding a small, white star. The gas is usually illuminated by the star, producing a variety of colours and shapes.

a great cloud of gas that was blown off by an old star.

A shell of gas ejected from, and enlarging about, a certain kind of extremely hot star that is nearing the end of its life.

A type of nebular where a cloud of gas that has been discharged by a central star.

a glowing shell of gas ejected by a dying low-mass star.

A low-mass star in the final stages of its life that illuminates the outer gas layers that it has previously ejected. Can resemble a planet through a small telescope, but otherwise not related to planets. How can a star become a black hole

Only happens in small stars, when the helium core runs out the outer layers drift away from the core.

a bright nebula thrown off by a dying star

A thick shell of gas ejected from and moving out from an extremely hot star; thought to be the outer layers of a red giant star thrown out into space, the core of which eventually becomes a white dwarf.

A very hot star surrounded by expanding gases that give off a glow because of intense radiation from the star.

The remains of a main sequence star towards the end of its evolution into a white dwarf. The outer layers of the star have been released into the surrounding environment and often form complex and beautiful structures around the intensely hot core. As planetary nebula are very common objects, there are only a few on the galaxy map; mostly near to our Sun or very large ones that were previously mistaken for HII regions. The term "planetary" is a misnomer - these nebula appeared as faint planet-like globes in early telescopes.

A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. They are in fact unrelated to planets; the name originates from a supposed similarity in appearance to giant planets. They are a short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.