query: star left at the core of a planetary nebula

pos: Planetary nebula that it does not give off enough ultraviolet radiation to ionize the increasingly distant gas cloud. The star becomes a white dwarf, and the expanding gas cloud becomes invisible to us, ending the planetary nebula phase of evolution. For a typical planetary nebula, about 10,000 years passes between its formation and recombination of the resulting plasma. Planetary nebulae may play a very important role in galactic evolution. Newly born stars consist almost entirely of hydrogen and helium, but as stars evolve through the asymptotic giant branch phase, they create heavier elements via nuclear fusion which are eventually expelled by strong

pos: Hen 2-428 Hen 2-428 Hen 2-428 is a planetary nebula with a binary double white dwarf system core. This core star system is the first discovered candidate for Type Ia supernova through binary white dwarf merger process. At the time of its discovery, the star system at the core was the heaviest known double white dwarf binary star system. The planetary nebula is asymmetric, which is the result of there being not a single star, but a binary system at the heart of the nebula. The binary nature of the star at the centre of the nebula was discovered in 2014, when

pos: Hen 2-428 variations in the standard candle to reduce the error uncertainty in determining distance. Hen 2-428 Hen 2-428 is a planetary nebula with a binary double white dwarf system core. This core star system is the first discovered candidate for Type Ia supernova through binary white dwarf merger process. At the time of its discovery, the star system at the core was the heaviest known double white dwarf binary star system. The planetary nebula is asymmetric, which is the result of there being not a single star, but a binary system at the heart of the nebula. The binary nature of

pos: Helix Nebula Nebula has sometimes been referred to as the "Eye of God" in pop culture, as well as the "Eye of Sauron". The Helix Nebula is an example of a planetary nebula, formed by an intermediate to low-mass star, which sheds its outer layers near the end of its evolution. Gases from the star in the surrounding space appear, from our vantage point, as if we are looking down a helix structure. The remnant central stellar core, known as a planetary nebula nucleus or PNN, is destined to become a white dwarf star. The observed glow of the central star is

pos: Little Ghost Nebula Little Ghost Nebula Little Ghost Nebula is a planetary nebula in the constellation Ophiuchus. It was discovered by William Herschel. Round and planet-shaped, the nebula is also relatively faint. Planetary nebulae are not related to planets at all, but instead are created at the end of a sun-like star's life as its outer layers expand into space while the star's core shrinks to become a white dwarf. The transformed white dwarf star, seen near the center, radiates strongly at ultraviolet wavelengths and powers the expanding nebula's glow. The nebula's main ring structure is about a light-year across and the glow

pos: White dwarf hydrogen-burning shell. On the Hertzsprung–Russell diagram, it will be found on the asymptotic giant branch. It will then expel most of its outer material, creating a planetary nebula, until only the carbon–oxygen core is left. This process is responsible for the carbon–oxygen white dwarfs which form the vast majority of observed white dwarfs. If a star is massive enough, its core will eventually become sufficiently hot to fuse carbon to neon, and then to fuse neon to iron. Such a star will not become a white dwarf, because the mass of its central, non-fusing core, initially supported by electron degeneracy

pos: Red giant causing helium in a shell to begin fusing. At the same time hydrogen may begin fusion in a shell just outside the burning helium shell. This puts the star onto the asymptotic giant branch, a second red-giant phase. The helium fusion results in the build up of a carbon–oxygen core. A star below about will never start fusion in its degenerate carbon–oxygen core. Instead, at the end of the asymptotic-giant-branch phase the star will eject its outer layers, forming a planetary nebula with the core of the star exposed, ultimately becoming a white dwarf. The ejection of the outer mass

pos: IC 418 spans 0.3 light-years across. IC 418 IC 418, also known as Spirograph Nebula, is a planetary nebula in the Milky Way Galaxy. The name derives from the intricate pattern of the nebula, which resembles a pattern which can be created using the Spirograph, a toy that produces geometric patterns (specifically, hypotrochoids and epitrochoids) on paper. Only a few million years ago, IC 418 was probably a common red giant star. Since running out of nuclear fuel, though, the outer envelope has begun expanding outward leaving a hot remnant core destined to become a white dwarf star. IC 418 lies about

pos: IC 418 IC 418 IC 418, also known as Spirograph Nebula, is a planetary nebula in the Milky Way Galaxy. The name derives from the intricate pattern of the nebula, which resembles a pattern which can be created using the Spirograph, a toy that produces geometric patterns (specifically, hypotrochoids and epitrochoids) on paper. Only a few million years ago, IC 418 was probably a common red giant star. Since running out of nuclear fuel, though, the outer envelope has begun expanding outward leaving a hot remnant core destined to become a white dwarf star. IC 418 lies about 3600 light-years away and

pos: Alpha Ceti Menkar the red hue of an M-type star. Menkar has evolved from the main sequence after exhausting the hydrogen at its core. It has also exhausted its core helium, becoming an asymptotic giant branch star, and will probably become a highly unstable star like Mira before finally shedding its outer layers and forming a planetary nebula, leaving a relatively large white dwarf remnant. It has been observed to vary in brightness, but only with an amplitude of about one hundredth of a magnitude. "Menkar" (AK-123) was a United States Navy Crater class cargo ship named after the star. Alpha Ceti

pos: NGC 3132 of its intense ultraviolet radiation. NGC 3132 NGC 3132, also known as the Eight-Burst Nebula, the Southern Ring Nebula, is a bright and extensively studied planetary nebula in the constellation Vela. Its distance from Earth is estimated at about 550 pc. or 2,000 light-years. Images of NGC 3132 reveal two stars close together within the nebulosity, one of 10th magnitude, the other 16th. The central planetary nebula nucleus (PNN) or white dwarf central star is the fainter of these two stars. This hot central star of about 100,000 K has now blown off its layers and is making the nebula

pos: NGC 3132 NGC 3132 NGC 3132, also known as the Eight-Burst Nebula, the Southern Ring Nebula, is a bright and extensively studied planetary nebula in the constellation Vela. Its distance from Earth is estimated at about 550 pc. or 2,000 light-years. Images of NGC 3132 reveal two stars close together within the nebulosity, one of 10th magnitude, the other 16th. The central planetary nebula nucleus (PNN) or white dwarf central star is the fainter of these two stars. This hot central star of about 100,000 K has now blown off its layers and is making the nebula fluoresce brightly from the emission

pos: Astronomy is in turn consumed. Very massive stars can also undergo a series of evolutionary phases, as they fuse increasingly heavier elements. The final fate of the star depends on its mass, with stars of mass greater than about eight times the Sun becoming core collapse supernovae; while smaller stars blow off their outer layers and leave behind the inert core in the form of a white dwarf. The ejection of the outer layers forms a planetary nebula. The remnant of a supernova is a dense neutron star, or, if the stellar mass was at least three times that of the

pos: Stellar evolution energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached

pos: White dwarf carbon and oxygen in its core by the triple-alpha process. If a red giant has insufficient mass to generate the core temperatures required to fuse carbon (around 1 billion K), an inert mass of carbon and oxygen will build up at its center. After such a star sheds its outer layers and forms a planetary nebula, it will leave behind a core, which is the remnant white dwarf. Usually, white dwarfs are composed of carbon and oxygen. If the mass of the progenitor is between 8 and 10.5 solar masses (), the core temperature will be sufficient to fuse carbon

pos: Epsilon Boötis orange hue of a K-type star. The companion star has a classification of A2 V, so it is a main sequence star that is generating energy through the thermonuclear fusion of hydrogen at its core. This star is rotating rapidly, with a projected rotational velocity of By the time the smaller main sequence star reaches the current point of the primary in its evolution, the larger star will have lost much of its mass in a planetary nebula and will have evolved into a white dwarf. The pair will have essentially changed roles: the brighter star becoming the dim dwarf,

pos: NGC 6302 NGC 6302 NGC 6302, also called the Bug Nebula, Butterfly Nebula, is a bipolar planetary nebula in the constellation Scorpius. The structure in the nebula is among the most complex ever observed in planetary nebulae. The spectrum of NGC 6302 shows that its central star is one of the hottest stars in the galaxy, with a surface temperature in excess of 250,000 degrees Celsius, implying that the star from which it formed must have been very large ("cf." PG 1159 star). The central star, a white dwarf, was only recently discovered , using the upgraded Wide Field Camera 3 on

pos: Nebula has lost enough material, its temperature increases and the ultraviolet radiation it emits can ionize the surrounding nebula that it has thrown off. Our Sun will produce a planetary nebula and its core will remain behind in the form of white dwarf. Objects named nebulae belong to four major groups. Before their nature was understood, galaxies ("spiral nebulae") and star clusters too distant to be resolved as stars were also classified as nebulae, but no longer are. Not all cloud-like structures are named nebulae; Herbig–Haro objects are an example. Most nebulae can be described as diffuse nebulae, which means that

pos: Stingray Nebula (AGB) B1 supergiant. Planetary nebula (PN) emission lines were identified in this star in 1989 by the IUE (Parthasarathy et al. 1993). As the nebula would be newly formed and very small, ground-based observations were not able to resolve it; so Bobrowsky observed it with the Hubble Space Telescope, discovering the nebula, which he named the "Stingray Nebula." In 1995 the central planetary nebula nucleus (PNN) was observed as a DA white dwarf, having seemingly faded by a factor of three between 1987 and 1995. The PNN has an estimated mass of , and has an observed companion star separated

pos: Carbon-burning process outer envelope in a planetary nebula. In stars with masses between 8 and 11 solar masses, the carbon-oxygen core is under degenerate conditions and carbon ignition takes place in a "carbon flash", that lasts just milliseconds and disrupts the stellar core. In the late stages of this nuclear burning they develop a massive stellar wind, which quickly ejects the outer envelope in a planetary nebula leaving behind an O-Ne-Na-Mg white dwarf core of about 1.1 solar masses. The core never reaches high enough temperature for further fusion burning of heavier elements than carbon. Stars with more than 11 solar masses

pos: Nebulae in fiction 45 variable stars of the T Tauri type, young stars still in the process of formation, as well as some 17 Herbig–Haro objects are known in this nebula. Planetary nebula cataloged as NGC 2440. Its central star, HD62166, is possibly the hottest known white dwarf. The nebula, situated in the Puppis constellation, was discovered in 1790 by William Herschel, who described it as a "beautiful planetary nebula of a considerable degree of brightness, not very well defined." The nebula is located about 4,000 light years from the Sun, has a spectacular appearance and is located in a rich star field.

pos: Saturn Nebula Saturn Nebula The Saturn Nebula or NGC 7009 is a planetary nebula in the constellation Aquarius. It appears as a greenish-yellowish hue in a small amateur telescope. It was discovered by William Herschel on September 7, 1782, using a telescope of his own design in the garden at his home in Datchet, England, and was one of his earliest discoveries in his sky survey. The nebula was originally a low-mass star that ejected its layers into space, forming the nebula. The central star is now a bright white dwarf star of apparent magnitude 11.5. The Saturn Nebula gets its name

pos: Gravitational collapse be halted only if it reaches a new state of equilibrium. Depending on the mass during its lifetime, these stellar remnants can take one of three forms: The collapse of the stellar core to a white dwarf takes place over tens of thousands of years, while the star blows off its outer envelope to form a planetary nebula. If it has a companion star, a white dwarf-sized object can accrete matter from the companion star. Before it reaches the Chandrasekhar limit (about one and a half times the mass of our Sun, at which point gravitational collapse would take start

pos: Future of Earth trajectory towards the Sun may remove Earth's mantle, leaving just its core, which will finally be destroyed after at most 200 years. Following this event, Earth's sole legacy will be a very slight increase (0.01%) of the solar metallicity. After fusing helium in its core to carbon, the Sun will begin to collapse again, evolving into a compact white dwarf star after ejecting its outer atmosphere as a planetary nebula. The predicted final mass is 54.1% of the present value, most likely consisting primarily of carbon and oxygen. Currently, the moon is moving away from Earth at a rate of

pos: NGC 2440 dense star, with an estimated 0.6 solar mass and 0.028 solar radius, has an apparent magnitude of 17.5. NGC 2440 NGC 2440 is a planetary nebula, one of many in our galaxy. Its central star, HD62166, is possibly the hottest known white dwarf. The nebula is situated in the constellation Puppis. It was discovered by William Herschel on March 4, 1790. He described it as "a beautiful planetary nebula of a considerable degree of brightness, not very well defined." The nebula is located about 1.23 kiloparsecs (3.79×10 m) or about 4,000 light years from the Sun. HD 62166 has an

pos: Variable star caused by a white dwarf or a star core reaching a certain mass/density limit, the Chandrasekhar limit, causing the object to collapse in a fraction of a second. This collapse "bounces" and causes the star to explode and emit this enormous energy quantity. The outer layers of these stars are blown away at speeds of many thousands of kilometers an hour. The expelled matter may form nebulae called "supernova remnants". A well-known example of such a nebula is the Crab Nebula, left over from a supernova that was observed in China and North America in 1054. The core of the

pos: NGC 2818 NGC 2818 NGC 2818 is a planetary nebula located in the southern constellation Pyxis (The Compass). It consists largely of glowing gases from the star's outer layers ejected during the final stages of its life when it had run out of the fuel necessary to sustain its core fusion processes. The remnants of its core will remain as a white dwarf. It is often cited as a member of the open cluster NGC 2818A framing it, however, radial velocity differences between the planetary nebula and open cluster suggest a chance alignment. The case is an example of a superimposed pair,

pos: Sun The luminosity stays approximately constant as the temperature increases, with the ejected half of the Sun's mass becoming ionised into a planetary nebula as the exposed core reaches 30,000 K. The final naked core, a white dwarf, will have a temperature of over 100,000 K, and contain an estimated 54.05% of the Sun's present day mass. The planetary nebula will disperse in about 10,000 years, but the white dwarf will survive for trillions of years before fading to a hypothetical black dwarf. The Sun lies close to the inner rim of the Milky Way's Orion Arm, in the Local Interstellar

pos: NGC 1360 NGC 1360 NGC 1360, also known as the Robin's Egg Nebula, is a planetary nebula in the constellation of Fornax. It was identified as a planetary nebula due to its strong radiation in the OIII (oxygen) bands. Reddish matter, believed to have been ejected from the original star before its final collapse, is visible in images. It is slightly fainter than IC 2003. In 2017 it was discovered the central source was a long period double degenerate in a 142-day orbit, with masses of 0.555 (Central Star) and 0.70 (White Dwarf Companion) Solar Masses respectively. Although it was suspected to

pos: NGC 6905 nebulae. Moreover, O emission has been detected in NGC 6905. The ansae were particularly intense in N. The central star, a white dwarf is estimated to have surface temperature 150.000 K. NGC 6905 can be detected under dark skies with a 4-inch telescope, but it better observed with larger instruments. NGC 6905 NGC 6905, also known as the Blue Flash Nebula, is a planetary nebula in the constellation Delphinus. It was discovered by William Herschel in 1784. The central star is 14.0 mag. The distance of the nebula, as with most planetary nebulae, is not well determined and estimates range

pos: La Superba to eject its outer layers to form a planetary nebula, leaving behind its core in the form of a white dwarf. La Superba La Superba (Y CVn, Y Canum Venaticorum) is strikingly red giant star in the constellation Canes Venatici. It is a carbon star and semiregular variable. La Superba is a semiregular variable star, varying by about a magnitude over a roughly 160-day cycle, but with slower variation over a larger range. Periods of 194 and 186 days have been suggested, with a resonance between the periods. Y CVn is one of the reddest stars known, and it is

pos: IK Pegasi the star's outer envelope. This ejected material formed an immense cloud of material called a planetary nebula. All but a small fraction of the hydrogen envelope was driven away from the star, leaving behind a white dwarf remnant composed primarily of the inert core. The interior of IK Pegasi B may be composed wholly of carbon and oxygen; alternatively, if its progenitor underwent carbon burning, it may have a core of oxygen and neon, surrounded by a mantle enriched with carbon and oxygen. In either case, the exterior of IK Pegasi B is covered by an atmosphere of almost pure

pos: Chi Cygni then around 6 million years to reach the TP-AGB, and spend one million years in the TP-AGB phase. It will lose around before the TP-AGB and on the TP-AGB. The carbon-oxygen core of will go on to become a white dwarf and the remaining envelope will be shed to possibly become a planetary nebula. Chi Cygni Chi Cygni (Latinised from χ Cygni) is a Mira variable star in the constellation Cygnus, and also an S-type star. It is around 500 light years away. χ Cygni is an asymptotic giant branch star, a very cool and luminous red giant nearing the

pos: NGC 2440 NGC 2440 NGC 2440 is a planetary nebula, one of many in our galaxy. Its central star, HD62166, is possibly the hottest known white dwarf. The nebula is situated in the constellation Puppis. It was discovered by William Herschel on March 4, 1790. He described it as "a beautiful planetary nebula of a considerable degree of brightness, not very well defined." The nebula is located about 1.23 kiloparsecs (3.79×10 m) or about 4,000 light years from the Sun. HD 62166 has an exceptionally high surface temperature of about 200,000 kelvins and a luminosity 1,100 times that of the Sun. This

pos: Shapley 1 Shapley 1 Shapley 1 ("Sp 1" or "PLN 329+2.1") is an annular planetary nebula in the constellation of Norma with a magnitude of +12.6. As viewed from Earth, it is peculiar in that it seems to be a non-bipolar, torus-shaped planetary nebula. However, it is thought that this is due to the viewpoint of looking directly down on a binary system whose orbit is perpendicular to Earth. Discovered in 1936 by Harlow Shapley, it is approximately 4900 light years from Earth, and is around 8700 years old. At the center of the nebula is a magnitude 14 white dwarf star.

pos: Jones-Emberson 1 basically represents the planetary nebula that when using the galactic coordinate system has a galactic longitude of 164 degrees, a galactic latitude of +31 degrees, and is the first such object in the Perek-Kohoutek catalog to occupy that particular one square degree area of sky). Jones-Emberson 1 Jones-Emberson 1 (PK 164+31.1) is a 14th magnitude planetary nebula in the constellation Lynx at a distance of 1600 light years. It is a larger planetary with low surface brightness. The 16.8-magnitude central star is a very blue white dwarf. Discovered in 1939 by R. Jones and R. Emberson, it's "PK" designation comes

pos: Solar System fraction of the time it burned hydrogen in the core. The Sun is not massive enough to commence the fusion of heavier elements, and nuclear reactions in the core will dwindle. Its outer layers will move away into space, leaving a white dwarf, an extraordinarily dense object, half the original mass of the Sun but only the size of Earth. The ejected outer layers will form what is known as a planetary nebula, returning some of the material that formed the Sun—but now enriched with heavier elements like carbon—to the interstellar medium. The Sun is the Solar System's star and

pos: Red supergiant star luminosity, around , when they are on the asymptotic giant branch (AGB) undergoing helium shell burning. Researchers now prefer to categorise these as AGB stars distinct from supergiants because they are less massive, have different chemical compositions at the surface, undergo different types of pulsation and variability, and will evolve in a different way, usually producing a planetary nebula and white dwarf. Most AGB stars will not become supernovae although there is interest in a class of "super-AGB" stars, those almost massive enough to undergo full carbon fusion, which may produce peculiar supernovae although without ever developing an iron core.

pos: Stellar evolution hotter and denser as it gains material from fusion of hydrogen at the base of the envelope. In all massive stars, electron degeneracy pressure is insufficient to halt collapse by itself, so as each major element is consumed in the center, progressively heavier elements ignite, temporarily halting collapse. If the core of the star is not too massive (less than approximately , taking into account mass loss that has occurred by this time), it may then form a white dwarf (possibly surrounded by a planetary nebula) as described above for less-massive stars, with the difference that the white dwarf is

neg: Planetary nebula exceeding about 30,000 K, there are enough emitted ultraviolet photons to ionize the ejected atmosphere, causing the gas to shine as a planetary nebula. After a star passes through the asymptotic giant branch (AGB) phase, the short planetary nebula phase of stellar evolution begins as gases blow away from the central star at speeds of a few kilometers per second. The central star is the remnant of its AGB progenitor, an electron-degenerate carbon-oxygen core that has lost most of its hydrogen envelope due to mass loss on the AGB. As the gases expand, the central star undergoes a two-stage evolution,

neg: Planetary nebula Once most of the red giant's atmosphere is dissipated, ultraviolet radiation from the hot luminous core, called a planetary nebula nucleus (PNN), ionizes the ejected material. Absorbed ultraviolet light then energises the shell of nebulous gas around the central star, causing it to appear as a brightly coloured planetary nebula. Planetary nebulae likely play a crucial role in the chemical evolution of the Milky Way by expelling elements to the interstellar medium from stars where those elements were created. Planetary nebulae are observed in more distant galaxies, yielding useful information about their chemical abundances. Starting from the 1990s, Hubble Space

neg: Boomerang Nebula Boomerang Nebula 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 making it the coolest natural place currently known in the Universe. The Boomerang Nebula is believed to be a star system evolving toward the planetary nebula phase. It continues to form and develop due to the outflow of gas from its core where a star is in its late stage life sheds mass and emits starlight illuminating dust in the nebula.

neg: Emission nebula both reflection and emission components such as the Trifid Nebula. Emission nebula An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them. Usually, a young star will

neg: Emission nebula Emission nebula An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy photons emitted from a nearby hot star. Among the several different types of emission nebulae are H II regions, in which star formation is taking place and young, massive stars are the source of the ionizing photons; and planetary nebulae, in which a dying star has thrown off its outer layers, with the exposed hot core then ionizing them. Usually, a young star will ionize part of the same cloud from which it was

neg: Crab Nebula fusion reactions and collapses in on itself, releasing gravitational potential energy in a form that blows away the star's outer layers. The presence of a pulsar in the Crab Nebula means that it must have formed in a core-collapse supernova; Type Ia supernovae do not produce pulsars. Theoretical models of supernova explosions suggest that the star that exploded to produce the Crab Nebula must have had a mass of between . Stars with masses lower than are thought to be too small to produce supernova explosions, and end their lives by producing a planetary nebula instead, while a star heavier

neg: Nebula produces. One of the best examples of this is the Crab Nebula, in Taurus. The supernova event was recorded in the year 1054 and is labeled SN 1054. The compact object that was created after the explosion lies in the center of the Crab Nebula and its core is now a neutron star. Still, other nebulae form as planetary nebulae. This is the final stage of a low-mass star's life, like Earth's Sun. Stars with a mass up to 8–10 solar masses evolve into red giants and slowly lose their outer layers during pulsations in their atmospheres. When a star

neg: Black hole its core temperature. In either case the star's temperature is no longer high enough to prevent it from collapsing under its own weight. The collapse may be stopped by the degeneracy pressure of the star's constituents, allowing the condensation of matter into an exotic denser state. The result is one of the various types of compact star. Which type forms depends on the mass of the remnant of the original star left after the outer layers have been blown away. Such explosions and pulsations lead to planetary nebula. This mass can be substantially less than the original star. Remnants exceeding

neg: Dumbbell Nebula Dumbbell Nebula The Dumbbell Nebula (also known as Apple Core Nebula, Messier 27, M 27, or NGC 6853) is a planetary nebula in the constellation Vulpecula, at a distance of about 1,360 light-years. This object was the first planetary nebula to be discovered; by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and its diameter of about 8 arcminutes, it is easily visible in binoculars, and a popular observing target in amateur telescopes. The Dumbbell Nebula appears to be shaped like an prolate spheroid and is viewed from our perspective along the plane of its equator. In

neg: Fleming 1 a torus of expanding hot gas forming the inner bright ellipse. Fleming 1 is probably 5,000 years old. Like any other planetary nebula Fleming 1 was formed when an old asymptotic giant branch (AGB) star lost its outer hydrogen-rich envelope, leaving behind a hot core (young white dwarf)—the central star of the nebula. The star in the center of Fleming 1 has a temperature of and mass of 0.56 . Observations performed by European Southern Observatory showed that the central star is in fact a double degenerate (made of two white dwarfs) binary with a period of days. The companion

neg: Little Ghost Nebula from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively. The Little Ghost Nebula should not be confused with the Ghost Nebula (Sh2-136) or the Ghost Head Nebula (NGC 2080). Little Ghost Nebula Little Ghost Nebula is a planetary nebula in the constellation Ophiuchus. It was discovered by William Herschel. Round and planet-shaped, the nebula is also relatively faint. Planetary nebulae are not related to planets at all, but instead are created at the end of a sun-like star's life as its outer layers expand into space while the star's core shrinks to become a white

neg: Little Dumbbell Nebula is now classed as a bipolar planetary nebula (BPNe). Distance to M76 is currently estimated as 780 parsecs or 2,500 light years, making the average dimensions about 0.378 pc. (1.23 ly.) across. The total nebula shines at the apparent magnitude of +10.1 with its central star or planetary nebula nucleus (PNN) at +15.9v (16.1B) magnitude. The UV-light from the PNN is expanding outer layers that form the present nebula, and has the surface temperature of about 88,400 K. The whole planetary nebula is approaching us at 19.1 km/s. The Little Dumbbell Nebula derives its common name from its resemblance to

neg: V605 Aquilae source of the nebula. The visible planetary nebula is approximately spherical and far older than the 1919 outburst. A much smaller nebula originating from the outburst is non-spherical. The shape may be a disc plus a bipolar nebula or torus containing a dusty band. The band or disc almost entirely obscures the central star. Comparison of the angular size changes of the nebula and its radial velocities suggest a distance of 4,600 parsecs. V605 Aquilae V605 Aquilae, in the constellation Aquila, is the variable central star of the planetary nebula Abell 58. It is a highly unusual hydrogen-deficient carbon-rich star.

neg: Aquarius (constellation) resemble Saturn's rings. It appears blue-green in a telescope and has a central star of magnitude 11.3. Compared to the Helix Nebula, another planetary nebula in Aquarius, it is quite small. NGC 7293, also known as the Helix Nebula, is the closest planetary nebula to Earth at a distance of 650 light-years. It covers 0.25 square degrees, making it also the largest planetary nebula as seen from Earth. However, because it is so large, it is only viewable as a very faint object, though it has a fairly high integrated magnitude of 6.0. One of the visible galaxies in Aquarius

neg: NGC 2346 the two stars evolved into a red giant, it engulfed its companion, which stripped away a ring of material from the larger star’s atmosphere. When the red giant’s core was exposed, a fast stellar wind inflated two ‘bubbles’ from either side of the ring. NGC 2346 NGC 2346 (also known as the Butterfly Nebula) is a planetary nebula near the celestial equator in the constellation Monoceros. It is bright and conspicuous and has been extensively studied. Among its most remarkable characteristics is its unusually cool central star, which is a spectroscopic binary, and its unusual shape. The binary star, which

neg: Helix Nebula for the inner disk. Spectroscopically, the outer ring's expansion rate is 40 km·s, and about 32 km·s for the inner disk. The Helix Nebula was the first planetary nebula discovered to contain cometary knots. Its main ring contains knots of nebulosity, which have now been detected in many nearby planetaries. These knots are highly radially symmetric (from the PNN) and are described as "cometary", each centered on a core of neutral molecular gas and containing bright cusps (local photoionization fronts) towards the central star and tails away from it. All tails extend away from the PNN in a radial direction.

neg: Abell 39 the face of the shell. The source of the east-west asymmetry is not known but it could be related to the offset of the central star. The central star is classified as a subdwarf O star. The bright rim of the planetary nebula has an average thickness of about 10″.1 or about 0.34 light-years. There is a faint halo that extends about 18″ beyond the bright rim giving a complete diameter of around 190″ under the assumption that this emission is uniform around the planetary nebula. This planetary nebula has been expanding for an estimated 22,100 years, based on an

neg: Planetary nebula first growing hotter as it continues to contract and hydrogen fusion reactions occur in the shell around the core and then slowly cooling when the hydrogen shell is exhausted through fusion and mass loss. In the second phase, it radiates away its energy and fusion reactions cease, as the central star is not heavy enough to generate the core temperatures required for carbon and oxygen to fuse. During the first phase, the central star maintains constant luminosity, while at the same time it grows ever hotter, eventually reaching temperatures around 100,000 K. In the second phase, it cools so much

neg: NGC 3195 is estimated at about 1.7 kpc. NGC 3195 NGC 3195 is a planetary nebula located in the constellation Chamaeleon. It is the most southern of all the bright sizable planetary nebula in the sky, and remains invisible to all northern observers. Discovered by Sir John Herschel in 1835, this 11.6 apparent magnitude planetary nebula is slightly oval in shape, with dimensions of 40×35 arc seconds, and can be seen visually in telescopic apertures of at low magnifications. Spectroscopy reveals that NGC 3195 is approaching Earth at , while the nebulosity is expanding at around . The central star is listed

neg: NGC 3195 NGC 3195 NGC 3195 is a planetary nebula located in the constellation Chamaeleon. It is the most southern of all the bright sizable planetary nebula in the sky, and remains invisible to all northern observers. Discovered by Sir John Herschel in 1835, this 11.6 apparent magnitude planetary nebula is slightly oval in shape, with dimensions of 40×35 arc seconds, and can be seen visually in telescopic apertures of at low magnifications. Spectroscopy reveals that NGC 3195 is approaching Earth at , while the nebulosity is expanding at around . The central star is listed as >15.3V or 16.1B magnitude. Distance

neg: NGC 3918 is approaching us at 17±3.0 kilometres per second, while the nebulosity is expanding at around 24 kilometres per second. The central star is 14.6 visible light magnitude, and remains invisible to optical observers, as it is obscured by the sheer brightness of the surrounding nebula. The distance is estimated at 1.5 kpc (4 900 ly) . NGC 3918 NGC 3918 is a bright planetary nebula in the constellation Centaurus, nicknamed the "Blue Planetary" or "The Southerner". It is the brightest of the far southern planetary nebulae. This nebula was discovered by Sir John Herschel in March 1834, and is easily

neg: Gemini (constellation) light-years from Earth. Another open cluster in Gemini is NGC 2158. Visible in large amateur telescopes and very rich, it is more than 12,000 light-years from Earth. The Eskimo Nebula or Clown Face Nebula (NGC 2392) is a planetary nebula with an overall magnitude of 9.2, located 4,000 light-years from Earth. In a small amateur telescope, its 10th magnitude central star is visible, along with its blue-green elliptical disk. It is named for its resemblance to the head of a person wearing a parka. The Medusa Nebula is another planetary nebula, some 1,500 light-years distant. Geminga is a neutron star

neg: Nebula rapid stellar evolution between the late asymptotic giant branch (LAGB) phase and the following planetary nebula (PN) phase. During the AGB phase, the star undergoes mass loss, emitting a circumstellar shell of hydrogen gas. When this phase comes to an end, the star enters the PPN phase. The PPN is energized by the central star, causing it to emit strong infrared radiation and become a reflection nebula. Collimated stellar winds from the central star shape and shock the shell into an axially symmetric form, while producing a fast moving molecular wind. The exact point when a PPN becomes a planetary

neg: Nebula similar to those of emission nebulae found in star formation regions. Technically they are HII regions, because most hydrogen are ionized, but are denser and more compact than nebulae found in star formation regions. Planetary nebulae were given their name by the first astronomical observers who were initially unable to distinguish them from planets, and who tended to confuse them with planets, which were of more interest to them. Our Sun is expected to spawn a planetary nebula about 12 billion years after its formation. A protoplanetary nebula (PPN) is an astronomical object at the short-lived episode during a star's

neg: Planetary nebula luminosity function PNLF cutoff dim by more than a small percentage. The relative independence of the PNLF cutoff with respect to population age is harder to understand. The [O III] λ5007 flux of a PNe directly correlates to the brightness of its central star. Further, the brightness of its central star directly correlates to its mass and the central star's mass directly varies in relation to its progenitor's mass. However, by observation, it is demonstrated that reduced brightness does not happen. Planetary nebula luminosity function Planetary nebula luminosity function (PNLF) is a secondary distance indicator used in astronomy. It makes use of

neg: Future of an expanding universe of low to medium mass, such as our own sun, will expel some of their mass as a planetary nebula and eventually become white dwarfs; more massive stars will explode in a core-collapse supernova, leaving behind neutron stars or black holes. In any case, although some of the star's matter may be returned to the interstellar medium, a degenerate remnant will be left behind whose mass is not returned to the interstellar medium. Therefore, the supply of gas available for star formation is steadily being exhausted. The Andromeda Galaxy is currently approximately 2.5 million light years away from our galaxy,

neg: NGC 40 dwarf star approximately the size of Earth. NGC 40 NGC 40 (also known as the Bow-Tie Nebula and Caldwell 2) is a planetary nebula discovered by William Herschel on November 25, 1788, and is composed of hot gas around a dying star. The star has ejected its outer layer which has left behind a smaller, hot star with a temperature on the surface of about 50,000 degrees Celsius. Radiation from the star causes the shed outer layer to heat to about 10,000 degrees Celsius, and is about one light-year across. About 30,000 years from now, scientists theorize that NGC 40

neg: Cat's Eye Nebula is O7 + [WR]–type star Calculations suggest the PNN is over one solar mass, from a theoretical initial 5 solar masses. The central Wolf-Rayet star has a radius of (452,000 km). The Cat's Eye Nebula, given in some sources, lies about three thousand light-years from Earth. The Cat's Eye was the first planetary nebula to be observed with a spectroscope by William Huggins on August 29, 1864. Huggins' observations revealed that the nebula's spectrum was non-continuous and made of a few bright emission lines, first indication that planetary nebulae consist of tenuous ionised gas. Spectroscopic observations at these wavelengths are

neg: Lemon Slice Nebula Lemon Slice Nebula IC 3568 is a planetary nebula that is 1.3 kiloparsecs (4500 ly) away from Earth in the constellation of Camelopardalis (just 7.5 degrees from Polaris). It is a relatively young nebula and has a core diameter of only about 0.4 light years. It was dubbed the Lemon Slice Nebula by Jim Kaler, due to its appearance in one false-colour image from the Hubble Space Telescope. The Lemon slice nebula is one of the most simple nebulae known, with an almost perfectly spherical morphology. The core of the nebula does not have a distinctly visible structure in formation

neg: Wolf–Rayet star as 98%, although less than half are actually observed to have a massive companion. The binary fraction in the Milky Way is around 20%, in line with theoretical calculations. A significant proportion of WR stars are surrounded by nebulosity associated directly with the star, not just the normal background nebulosity associated with any massive star forming region, and not a planetary nebula formed by a post-AGB star. The nebulosity presents a variety of forms and classification has been difficult. Many were originally catalogued as planetary nebulae and sometimes only a careful multi-wavelength study can distinguish a planetary nebula around a

neg: Abell 39 light-years. Its central star is slightly west of center by about 2″ or 0.1 light-years. This offset does not appear to be due to interaction with the interstellar medium, but instead, it is hypothesized that a small asymmetric mass ejection has accelerated the central star. The mass of the central star is estimated to be about with the material in the planetary nebula comprising an additional . This planetary nebula has a nearly uniform spherical shell. However, the eastern limb of the nebula is 50% more luminous than the western limb. Additionally, irregularities in the surface brightness are seen across

neg: Messier 15 Way galaxy. Its core has undergone a contraction known as 'core collapse' and it has a central density cusp with an enormous number of stars surrounding what may be a central black hole. Home to over 100,000 stars, the cluster is notable for containing a large number of variable stars (112) and pulsars (8), including one double neutron star system, M15 C. M15 also contains Pease 1, the first planetary nebula discovered within a globular cluster in 1928. Just three others have been found in globular clusters since then. At magnitude 6.2, M15 approaches naked eye visibility under good conditions

neg: Cotton Candy Nebula Cotton Candy Nebula The Cotton Candy Nebula is considered to fall into an unusual category of astronomical objects known as protoplanetary nebulae or post-AGB star. A proto-planetary nebulae is essentially 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. Which was launched in January 1982 and overlooked about 97 percent of the sky. It is also known as IRAS 17150-3224.

neg: Planetary nebula K, the available helium nuclei fuse into carbon and oxygen, so that the star again resumes radiating energy, temporarily stopping the core's contraction. This new helium burning phase (fusion of helium nuclei) forms a growing inner core of inert carbon and oxygen. Above it is a thin helium-burning shell, surrounded in turn by a hydrogen-burning shell. However, this new phase lasts only 20,000 years or so, a short period compared to the entire lifetime of the star. In either scenario, the venting of atmosphere continues unabated into interstellar space, but when the outer surface of the exposed core reaches temperatures

neg: NGC 6905 NGC 6905 NGC 6905, also known as the Blue Flash Nebula, is a planetary nebula in the constellation Delphinus. It was discovered by William Herschel in 1784. The central star is 14.0 mag. The distance of the nebula, as with most planetary nebulae, is not well determined and estimates range between 1.7 and 2.6 kpc. The shape of NGC 6905 is characterised by an internal shell with angular dimensions 47" ×34" and roughly conical extensions, with ansae-type formations along the major axis. The nucleus of the nebula possesses one of the most broad emission of O emission lines among planetary

neg: Cotton Candy Nebula ring structures around the nebulae are created throughout the red-giant stage which is the ultimate stage in stellar evolution. Cotton Candy Nebula The Cotton Candy Nebula is considered to fall into an unusual category of astronomical objects known as protoplanetary nebulae or post-AGB star. A proto-planetary nebulae is essentially 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. Which was

neg: NGC 40 NGC 40 NGC 40 (also known as the Bow-Tie Nebula and Caldwell 2) is a planetary nebula discovered by William Herschel on November 25, 1788, and is composed of hot gas around a dying star. The star has ejected its outer layer which has left behind a smaller, hot star with a temperature on the surface of about 50,000 degrees Celsius. Radiation from the star causes the shed outer layer to heat to about 10,000 degrees Celsius, and is about one light-year across. About 30,000 years from now, scientists theorize that NGC 40 will fade away, leaving only a white

neg: Planetary nebula possible to determine distances to the nearest planetary nebula by measuring their expansion rates. High resolution observations taken several years apart will show the expansion of the nebula perpendicular to the line of sight, while spectroscopic observations of the Doppler shift will reveal the velocity of expansion in the line of sight. Comparing the angular expansion with the derived velocity of expansion will reveal the distance to the nebula. The issue of how such a diverse range of nebular shapes can be produced is a debatable topic. It is theorised that interactions between material moving away from the star at

neg: Engraved Hourglass Nebula hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud which is denser near its equator than its poles. The vivid colours given off by the nebula are the result of different 'shells' of elements being expelled from the dying star, in this case helium, nitrogen, oxygen and carbon. The Hourglass Nebula was photographed by the Wide Field and Planetary Camera 2 of the Hubble Space Telescope. A less-famous "Hourglass Nebula" is located inside the Lagoon Nebula. Engraved Hourglass Nebula The Engraved Hourglass Nebula (also known as MyCn 18) is a young planetary

neg: WR 31a a planetary nebula, but rather as a much larger expanding gas shell, formally classified as a Wolf–Rayet nebula or WR nebula. Its observed expansion velocity is , and is estimated to be some across. The dynamical age of the nebula is estimated at 18,000 years and the total mass of ionised gas at . WR 31a itself, the highly luminous central star of the nebula, is invisible to the naked-eye at magnitude 10.85V. It has a spectral classification of WN11h, indicating a WR star with strong N emission but no N emission, and with hydrogen features visible in the spectrum.

neg: Necklace Nebula Necklace Nebula The Necklace Nebula (PN G054.2-03.4) is a 19-trillion-kilometre-wide ( light-year-wide) 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

neg: Westbrook Nebula of interaction between rapid bi-polar outflow and the gas that was ejected when the star was passing through its asymptotic giant branch phase. The lobes are inclined about 24° to the line of sight. The energy being radiated from the nebula consists of scattered light from the star at the core, light being emitted from a compact HII region surrounding the star, and energy from the shock-excited gas in the lobes. The core star is believed to be of spectral class B0 and has 12,200 times the solar luminosity. Westbrook Nebula Westbrook Nebula (CRL 618) is an aspherical protoplanetary nebula

neg: IC 2149 IC 2149 IC 2149 is a planetary nebula in the constellation of Auriga. It is a small, bright planetary nebula with something to offer in telescopes of most sizes. Visually it has an apparent magnitude of 10.6 and an apparent size of 12 arc seconds and like other objects of its class a nebular filter may help on its observation. Its distance to the Solar System has been estimated to be around 1.1 kiloparsecs, having a total mass of 0.03 solar masses and being thought to have been produced by a low-mass star. Some authors have proposed the planetary nebula

neg: Planetary nebula luminosity function abundance. At the same time, the PNe’s core responds to metallicity the opposite way. In the case where the metallicity of the progenitor star is smaller, the PNe’s central star will be a bit more massive and its illuminating ultraviolet flux will be a bit greater. This added energy almost precisely accounts for the decreased emissions of the PNe. Consequently, the total <nowiki>[O III]</nowiki> λ5007 lumonisity that is produced by a PNe is practically uncorrelated to metallicity. This beneficial negation is in agreement with more precise models of PNe evolution. Only in extremely metal-poor PNe does the brightness of the

neg: Corona Australis much further away. Near Epsilon and Gamma Coronae Australis is Bernes 157, a dark nebula and star forming region. It is a large nebula, 55 by 18 arcminutes, that possesses several stars around magnitude 13. These stars have been dimmed by up to 8 magnitudes by its dust clouds. IC 1297 is a planetary nebula of apparent magnitude 10.7, which appears as a green-hued roundish object in higher-powered amateur instruments. The nebula surrounds the variable star RU Coronae Australis, which has an average apparent magnitude of 12.9 and is a WC class Wolf–Rayet star. IC 1297 is small, at only

neg: NGC 7027 a molecule which is believed to exist in interstellar space, but which has never been conclusively identified. There is evidence for the presence of nanodiamond in NGC 7027. It was photographed by the Hubble Space Telescope in 1996. Prior to these observations, NGC 7027 was thought to be a proto-planetary nebula with the central star too cool to ionize any of the gas, but it is now known to be a planetary nebula in the earliest stage of its development. The progenitor star is believed to had been about 3–4 times the mass of the Sun before the nebula has

neg: Corvus (constellation) of 17 that brightens periodically to magnitude 12, discovered by Clyde Tombaugh in 1931 and David Levy in 1990 and 2005. Corvus contains no Messier objects. It has several galaxies and a planetary nebula observable with amateur telescopes. The center of Corvus is home to a planetary nebula, NGC 4361. The nebula itself resembles a small elliptical galaxy and has a magnitude of 10.3, but the magnitude 13 star at its centre gives away its true nature. The NGC 4038 Group is a group of galaxies across Corvus and Crater. The group may contain between 13 and 27 galaxies. The

neg: Stingray Nebula 15th-magnitude central star. The image of the Stingray Nebula shown here shows how the outer shells of gas are collimating the continuing outflow of gas from the central star—an important observation, as the process of how these outflows become collimated has not been well understood. Prior to the discovery of the nebula, the central star of the Stingray Nebula was known as He3-1357, which Karl Gordon Henize classified as an A or B type Hα emission line star in 1967. It was observed in 1971 to be a pre-planetary nebula (PPNe) when it seemed to be an asymptotic giant branch

neg: NGC 6751 to select an astronomical target to be imaged by Gemini. NGC 6751 NGC 6751, also known as the Glowing Eye Nebula, is a planetary nebula in the constellation Aquila. The nebula is estimated to be around 0.8 light-years in diameter. The star at the centre of the nebula has a surface temperature of approximately 140,000 K. It has been calculated to be roughly 6,500 light-years away from Earth. It was formed when a star collapsed and threw off its outer layer of gas several thousand years ago. The nebula was the subject of the winning picture in the 2009 Gemini

neg: NGC 6751 NGC 6751 NGC 6751, also known as the Glowing Eye Nebula, is a planetary nebula in the constellation Aquila. The nebula is estimated to be around 0.8 light-years in diameter. The star at the centre of the nebula has a surface temperature of approximately 140,000 K. It has been calculated to be roughly 6,500 light-years away from Earth. It was formed when a star collapsed and threw off its outer layer of gas several thousand years ago. The nebula was the subject of the winning picture in the 2009 Gemini School Astronomy Contest, in which Australian high school students competed

neg: Triangulum Australe year. Triangulum Australe has few deep-sky objects—one open cluster and a few planetary nebulae and faint galaxies. NGC 6025 is an open cluster with about 30 stars ranging from 7th to 9th magnitude. Located 3 degrees north and 1 east of Beta Trianguli Australis, it lies about away and is about in diameter. Its brightest star is MQ Trianguli Australis at apparent magnitude 7.1. NGC 5979, a planetary nebula of apparent magnitude 12.3, has a blue-green hue at higher magnifications, while Henize 2-138 is a smaller planetary nebula of magnitude 11.0. NGC 5938 is a remote spiral galaxy around 300

neg: Serpens Despite the presence of the Milky Way in Serpens Cauda, one globular cluster can be found: NGC 6535, although invisible to the naked eye, can be made out in small telescopes just north of Zeta Serpentis. Rather small and sparse for a globular cluster, this cluster contains no known RR Lyrae variables, which is unusual for a globular cluster. MWC 922 is a star surrounded by a planetary nebula. Dubbed the Red Square Nebula due to its similarities to the Red Rectangle Nebula, the planetary nebula appears to be a nearly perfect square with a dark band around the equatorial

neg: Serpens regions. The nebula contains concentric rings, which are similar to those seen in the supernova SN 1987A. MWC 922 itself is an FS Canis Majoris variable, meaning that it is a Be star containing exceptionally bright hydrogen emission lines as well as select forbidden lines, likely due to the presence of a close binary. East of Xi Serpentis is another planetary nebula, Abell 41, containing the binary star MT Serpentis at its center. The nebula appears to have a bipolar structure, and the axis of symmetry of the nebula has been found to be within 5° of the line perpendicular

neg: Orion (space telescope) December 1973, a spacecraft modified to become the first manned space observatory. The observatory was operated by crew member Valentin Lebedev. The designer of the observatory was Grigor Gurzadyan, then at Garni Space Astronomy Laboratory in Armenia. Ultraviolet spectrograms of thousands of stars to as faint as 13th stellar magnitude were obtained by a wide-angle meniscus telescope. The first satellite UV spectrogram of a planetary nebula (IC 2149) was obtained, revealing spectral lines of aluminum and titanium - elements not previously observed in planetary nebulae. Two-photon emission in that planetary nebula and a remarkable star cluster in Auriga were also

neg: Stellar mass loss such as the beginning of a helium flash in the core. The final stage of a red giant's life will also result in prodigious mass loss as the star loses its outer layers to form a planetary nebula. Stellar mass loss Stellar mass loss is a phenomenon observed in some massive stars. It occurs when a triggering event causes the ejection of a large portion of the star's mass. Stellar mass loss can also occur when a star gradually loses material to a binary companion or into interstellar space. A number of factors can contribute to the loss of mass

neg: Ring Nebula existence shows they are probably only located closer to the ionization front than those found in the Lupus planetary IC 4406. Some of the knots do exhibit well-developed tails which are often detectable in optical thickness from the visual spectrum. The central PNN was discovered by Hungarian astronomer Jenő Gothard on September 1, 1886, from images taken at his observatory in Herény, near Szombathely (now part of Szombathely). Within the last two thousand years, the central star of the Ring Nebula has left the asymptotic giant branch after exhausting its supply of hydrogen fuel. Thus it no longer produces its

neg: Lemon Slice Nebula and is mostly composed of ionized helium. A faint halo of interstellar dust surrounds the nebula. Lemon Slice Nebula IC 3568 is a planetary nebula that is 1.3 kiloparsecs (4500 ly) away from Earth in the constellation of Camelopardalis (just 7.5 degrees from Polaris). It is a relatively young nebula and has a core diameter of only about 0.4 light years. It was dubbed the Lemon Slice Nebula by Jim Kaler, due to its appearance in one false-colour image from the Hubble Space Telescope. The Lemon slice nebula is one of the most simple nebulae known, with an almost perfectly

neg: NGC 6302 lobes that may have belonged to a previous phase of mass loss. A dark lane runs through the waist of the nebula obscuring the central star at all wavelengths. Observations of NGC 6302 suggest that there may be an orthogonal skirt (or chakram) similar to that found in Menzel 3 The nebula is orientated at an angle of 12.8° against the plane of the sky. This planetary nebula contains a prominent northwest lobe which extends up to 3′.0 away from the central star and is estimated to have formed from an eruptive event around 1,900 years ago. It has a

neg: Mu Hydrae Mu Hydrae μ Hydrae, Latinised as Mu Hydrae, is a solitary, orange-hued star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 3.83. Positioned just 1.8° to the south-southwest is the planetary nebula NGC 3242. Mu Hydrae has an annual parallax shift of 13.93 mas, which yields a distance estimate of 234 light years. This is an evolved K-type giant star with a stellar classification of K4 III, having used up its core hydrogen and has expanded to around 45 times the radius of the Sun. It is a suspected

neg: NGC 7027 formed. In a 6" telescope at around 50x it appears as a relatively bright bluish star. At magnifications around 180x a vaguely ursine shape has led to the epithet of the "Gummy Bear Nebula". It is best viewed with the highest magnification possible. NGC 7027 NGC 7027 is a very young and dense planetary nebula located around away in the constellation Cygnus. It was discovered in 1878 by Édouard Stephan, using the 31 inch reflector at Marseille Observatory. It is one of the smallest planetary nebulae, and by far the most extensively studied. NGC 7027 is one of the visually

neg: Necklace Nebula 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. Necklace Nebula The Necklace Nebula (PN G054.2-03.4) is a 19-trillion-kilometre-wide ( light-year-wide) planetary nebula located