This is a list of protoplanetary nebulae . These objects represent the final stage before a planetary nebula. During this stage, the red giant star begins to slowly expel its outermost layers of material. A protoplanetary nebula usually glows by reflecting the light from its parent star. This stage is usually brief, typically lasting no more than a few thousand years.
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| Image | Name | NGC | Other designation | Date discovered | Distance (ly) |
|---|---|---|---|---|---|
 | Boomerang Nebula | Centaurus Bipolar Nebula | About 5,000 | ||
 | Calabash Nebula | OH231.8+4.2 | About 4,200 | ||
 | Egg Nebula | CRL 2688 | 1996 | About 3,000 | |
 | Frosty Leo Nebula | IRAS 09371+1212 | About 3,000 | ||
 | Red Rectangle Nebula | HD 44179 | 1973 | 2,300 ± 300 | |
 | Cotton Candy Nebula | IRAS 17150-3224 | |||
 | Water lily nebula | IRAS 16594-4656 | |||
 | IRAS 22036+5306 | About 6,500 | |||
 | Westbrook Nebula | IRAS 04395+3601 | |||
 | IRAS 13208-6020 | ||||
 | IRAS 20068+4051 | ||||
 | LL Pegasi | IRAS 23166+1655 | |||
 | M1-92 | IRAS 19343+2926 | About 8000 | ||
 | IRAS 19024+0044 | 11 000 | |||
 | Minkowski's Butterfly | M2-9 | 2 100 | ||
 | Roberts 22 (MR 22) | AFGL 4104 |
| Visible nebula | |
|---|---|
| Pre-stellar nebulae | |
| Stellar nebula | |
| Post-stellar nebulae | |
| Clouds | |
| Morphology | |
| Intergalactic blobs | |
 Lists |
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| Related | |
A nebula is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions, the formations of gas, dust, and other materials "clump" together to form denser regions, which attract further matter and eventually become dense enough to form stars. The remaining material is then thought to form planets and other planetary system objects.
The Orion Nebula is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion, and is known as the middle "star" in the "sword" of Orion. It is one of the brightest nebulae and is visible to the naked eye in the night sky with apparent magnitude 4.0. It is 1,344 ± 20 light-years (412.1 ± 6.1 pc) away and is the closest region of massive star formation to Earth. The M42 nebula is estimated to be 24 light-years across. It has a mass of about 2,000 times that of the Sun. Older texts frequently refer to the Orion Nebula as the Great Nebula in Orion or the Great Orion Nebula.
Planetesimals are solid objects thought to exist in protoplanetary disks and debris disks. Believed to have formed in the Solar System about 4.6 billion years ago, they aid study of its formation.
The Boomerang Nebula is a protoplanetary nebula located 5,000 light-years away from Earth in the constellation Centaurus. It is also known as the Bow Tie Nebula and catalogued as LEDA 3074547. The nebula's temperature is measured at 1 K making it the coolest natural place currently known in the Universe.
The nebular hypothesis is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System. It suggests the Solar System is formed from gas and dust orbiting the Sun which clumped up together to form the planets. The theory was developed by Immanuel Kant and published in his Universal Natural History and Theory of the Heavens (1755) and then modified in 1796 by Pierre Laplace. Originally applied to the Solar System, the process of planetary system formation is now thought to be at work throughout the universe. The widely accepted modern variant of the nebular theory is the solar nebular disk model (SNDM) or solar nebular model. It offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. Some elements of the original nebular theory are echoed in modern theories of planetary formation, but most elements have been superseded.
A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may also be considered an accretion disk for the star itself, because gases or other material may be falling from the inner edge of the disk onto the surface of the star. This process should not be confused with the accretion process thought to build up the planets themselves. Externally illuminated photo-evaporating protoplanetary disks are called proplyds.
A proplyd, short for ionized protoplanetary disk, is an externally illuminated photoevaporating protoplanetary disk around a young star. Nearly 180 proplyds have been discovered in the Orion Nebula. Images of proplyds in other star-forming regions are rare, while Orion is the only region with a large known sample due to its relative proximity to Earth.
Photoevaporation is the process where energetic radiation ionises gas and causes it to disperse away from the ionising source. The term is typically used in an astrophysical context where ultraviolet radiation from hot stars acts on clouds of material such as molecular clouds, protoplanetary disks, or planetary atmospheres.
The Egg Nebula is a bipolar protoplanetary nebula approximately 3,000 light-years away from Earth. Its peculiar properties were first described in 1975 using data from the 11 µm survey obtained with sounding rocket by Air Force Geophysical Laboratory (AFGL) in 1971 to 1974.
In astrophysics, accretion is the accumulation of particles into a massive object by gravitationally attracting more matter, typically gaseous matter, into an accretion disk. Most astronomical objects, such as galaxies, stars, and planets, are formed by accretion processes.
A protoplanetary nebula or preplanetary nebula is an astronomical object which is at the short-lived episode during a star's rapid evolution between the late asymptotic giant branch (LAGB) phase and the subsequent planetary nebula (PN) phase. A PPN emits strongly in infrared radiation, and is a kind of reflection nebula. It is the second-from-the-last high-luminosity evolution phase in the life cycle of intermediate-mass stars.
M1-92, also known as Minkowski’s Footprint or the Footprint Nebula, is a bipolar protoplanetary nebula in the constellation of Cygnus. It is a type of reflection nebula, visible only by light reflected from the central star. The central star is not yet a white dwarf but is quickly becoming one. In a few thousand years the star will be hot enough to emit vast quantities of ultraviolet radiation that will ionize the nebula surrounding it, making it a fully fledged planetary nebula.
The Red Rectangle Nebula, so called because of its red color and unique rectangular shape, is a protoplanetary nebula in the Monoceros constellation. Also known as HD 44179, the nebula was discovered in 1973 during a rocket flight associated with the AFCRL Infrared Sky Survey called Hi Star. The binary system at the center of the nebula was first discovered by Robert Grant Aitken in 1915.
A bipolar outflow comprises two continuous flows of gas from the poles of a star. Bipolar outflows may be associated with protostars, or with evolved post-AGB stars.
The Cotton Candy Nebula is an astronomical object in the constellation of Scorpius. It is considered to fall into an unusual category of nebulae known as protoplanetary nebulae or post-AGB stars. A proto-planetary nebulae is an astronomical object that is in a stellar evolution phase where the star begins to discard its outer layers and is about to proceed to becoming a true planetary nebula, which is another astronomical object made up mostly of gaseous materials that was originally discovered by the IRAS satellite. IRAS was launched in January 1982 and overlooked about 97 percent of the sky. It is also known as IRAS 17150-3224. It is a good example of a DUPLEX-type protoplanetary nebula.
Sh2-155 is a diffuse nebula in the constellation Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. It is widely known as the Cave Nebula, though that name was applied earlier to Ced 201, a different nebula in Cepheus. Sh2-155 is an ionized H II region with ongoing star formation activity, at an estimated distance of 725 parsecs from Earth.
Westbrook Nebula is a bipolar protoplanetary nebula which is located in the constellation Auriga. It is being formed by a star that has passed through the red giant phase and has ceased nuclear fusion at its core. This star is concealed at the center of the nebula, and is ejecting gas and dust at velocities of up to 200 km/s. The nebula is named after William E. Westbrook, who died in 1975.
IRAS 23304+6147 is a protoplanetary nebula in the constellation Cassiopeia, 16,000 light years away. The central star is a G-type supergiant.
A post-AGB star is a type of luminous supergiant star of intermediate mass in a very late phase of stellar evolution. The post-AGB stage occurs after the asymptotic giant branch has ended. The stage sees the dying star, initially very cool and large, shrink and heat up. The duration of the post-AGB stage varies based on the star's initial mass, and can range from 100,000 years for a solar-mass star to just over 1,000 years for more massive stars. The timescale gets slightly shorter with lower metallicity.
A circumstellar disc is a torus, pancake or ring-shaped accretion disk of matter composed of gas, dust, planetesimals, asteroids, or collision fragments in orbit around a star. Around the youngest stars, they are the reservoirs of material out of which planets may form. Around mature stars, they indicate that planetesimal formation has taken place, and around white dwarfs, they indicate that planetary material survived the whole of stellar evolution. Such a disc can manifest itself in various ways.
