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Planetary nebulas

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What is a planetary nebula?

 Updated June 01, 2013

Planetary nebulae are simple spheres shaped planet when viewed through a small telescope. But the Hubble Space Telescope is able to show us today the details of these beautiful celestial objects. Planetary nebulae have spherical shapes varied, are balls of gas and fluorescent material expelled by a central star at the end of life. These are the winds of intense heat and radiation of the central white dwarf that create the characteristic shape of the nebulae. The central star dying, shining like a thousand Suns. It expels its outer gaseous layers and exposes its core burning whose strong ultraviolet radiation illuminates the ejected gas. Nebulae that show the death of a star are common, so that astronomers have been able to study closely the different steps of this scenario well understood. Planetary nebulae are the most beautiful cosmic objects that can be admired with a large telescope. Ultraviolet radiation from the central star excites the atoms of the matter ejected, giving a different color characteristic to each element. Planetary nebulae do not live long they eventually disperse in less than 50,000 years.


NB: NGC (New General Catalog) is one of the best known catalogs in the field of amateur astronomy with the Messier catalog.

NB: IC (Index Catalogue of galaxies, nebulae and groups of Stars), serves as a supplement to the New General Catalogue.

NB: A (Abell catalog of clusters of galaxies). It is a catalog published in 1958 by George Abell (1927 - 1983) which lists 4073 clusters of galaxies.

Video: Life and death of stars, ordinary Jean-Pierre Luminet.


Butterfly Nebula or NGC 2346


The butterfly nebula is situated in the approximately 2000 years light of the Earth in the direction of the constellation of the Unicorn.
It is the last moments of the spectacular system of binary stars that we see on the photo opposite in the center of the nebula.
These two stars are so close as they orbit the one around the other one in 16 days. Even with Hubble, the pair of stars cannot be seen as two separate constituents.
The astronomers think that one of the stars, by evolving developed to become a red giant and literally absorbed her companion.
Stars swirled together in spirals, and most of the external layers of the red giant were ejected in a dense disk which surrounds now the central star.
The nebula is also rich in clouds of dust, among which some form of long streak sink who point far from the central star.


The spatial telescope Hubble arrested this image of the nebula in shape "of wing of butterfly", NGC 2346.

Image: The Butterfly Nebula seen by the Hubble Space Telescope.

 Butterfly Nebula

Ring Nebula or Lyre Nebula or M57


Lyre nebula or M57 is among objects the most known for the catalog Messier. It was discovered in 1779 by Antoine Darquier de Pellepoix. It is an annular nebula which looks like the nebula Helix a lot. The real diameter of the ring is 1,3 al, is about a visible diameter 2 min of bow. The visible ring consists of oxygen and nitrogen ionized. The outside edge of the ring consists as for him of hydrogen. The dark part inside the ring is made by helium, and emits in the ultraviolet ray. M57 is often named Misty of the Ring, Nebula of the Lyre or simply The Lyre, the name that she pulls of her constellation host. A global nebula is a fine disk, in the irregular forms and in the luxurious colors. We so called up them, because seen in a small instrument, in the debuts of the observations, they appeared as weak planets. They appear as a nebula of small angular dimensions, often very symmetric circular shape and bounded well, by opposition at the diffuse nebulas which seem to dilute in the space and of irregular shape.
Numerous global nebulas have a shape of ring, as the ring of the Lyre, opposite. They show a density of matter stronger in suburb than inside.


A star is always in the center. At the end of life, when they exhausted their hydrogen, stars see their peripheral layers dilating and cooling, whereas the heart collapses and warms up to reach the melting point of the helium. Certain stars go as far as ejecting their peripheral layers creating an expanding cocoon. The heart put in nude is a star of type W or O which shines a lot of ultraviolet light and which incites the nebula.

Image: In this composite image, visible-light observations by NASA’s Hubble Space Telescope are combined with infrared data from the ground-based Large Binocular Telescope in Arizona to assemble a dramatic view of the well-known Ring Nebula. Credit: NASA, ESA, C.R. Robert O’Dell (Vanderbilt University), G.J. Ferland (University of Kentucky), W.J. Henney and M. Peimbert (National Autonomous University of Mexico) Credit for Large Binocular Telescope data: David Thompson (University of Arizona).

 Ring Nebula, Lyre Nebula planetary or M57

Nebula Dumbbell or M57


In 1764, the French astronomer Charles Messier described this magnificent cloud cosmic as an oval nebula without star.
Cataloged under the name of M 27, it is now known under the name of Nebula Dumbbell ("barbell" in English) because of its lengthened shape, what the eyes of Messier had noticed.
This deep image of brilliant misty global reveal the central star of Dumbbell and a network of stars of front and back plan in the pinkish constellation of the Fox (Vulpecula in Latin).
The dissimilar image adds up 8 hours of pose through a filter intended to record only the light resulting from atoms of hydrogen, drawing the structure of the weak outside halo of the nebula which extends over light years.
The Nebula Dumbbell, is a nebula similar to the fact that will happen our Sun when it will have exhausted its nuclear fuel.


The central star (at the origin of the nebula) has a visible magnitude of 13,5, what makes it with difficulty observable for an amateur astronomer. It is a dwarf white with very warm blue color (85 000K). It is accompanied with another stud, even weaker (magnitude 17).

Image: Dumbell planetary Nebula or M57

 Dumbell planetary Nebula or M57

Helix Nebula or NGC 7293


The Helix nebula of the is a cosmic star often photographed by the amateur astronomers for its lively colors and its resemblance with a gigantic eye. The nebula discovered to 18th century, is situated in approximately 650 light years in the constellation of the Aquarius and belongs to a class of called objects misty global.
The global nebulas are the vestiges of stars which looked like in their past our Sun. When these stars die, they expel in the space their external gaseous layers.
These layers are warmed by the warm nucleus of the dead star, a white dwarf, and shine in the infrared and visible wavelengths.
Our Sun will undergo the same evolution when he will die in approximately five billion years. 
The infrared light of the external gaseous layers is represented in blue and in green.
The white dwarfish star is the tiny white point in the center of the photography.
The red color in the middle of the eye represents the last layers of gas blown during the death of the star.


The brilliant red circle situated in the center is the light of a disk of dust surrounding the white dwarfish star.
All the internal planets of the system were carbonized or vaporized whereas the volume of the dying star increased.

Image: The Helix nebula or NGC 7293 seen by the spatial telescope Spitzer

 Helix nebula or NGC 7293

Cat's Eye Nebula or NGC 6543


The Cat's Eye Nebula (NGC 6543 or of cat eye nebula) with a diameter of 20 seconds of bow, is situated in the north pole of the ecliptic, this very brilliant global nebula, is situated in the constellation of the Dragon.
This nebula possesses a very vast halo of matter, ejected during its phase of red giant. The halo measures 386 seconds of bow (5,8 minutes of bow).
According to a first interpretation, a binary system would be at the origin of the nebula.
The dynamic effects of two stars turning in orbit the one around the other one explain more easily the structure of this nebula, which seems much more complex than most of the other known global nebulas.
According to this model, the stellar wind of the central star created the envelope lengthened, made by dense and brilliant gas.
This structure is included inside two lobes of gas, ejected earlier by this star.
These lobes are marked by a ring of denser gas, probably ejected in the orbital plan of the companion of the central star.


Image: The Cat's Eye Nebula or NGC 6543 seen by the spatial telescope Hubble

 Cat's Eye Nebula or NGC 6543

Nebula NGC 2818


The planetary nebula NGC 2818 is nested inside the open cluster NGC 2818A Star and has a visual magnitude of 8.2 and therefore invisible to the naked eye. The cluster and nebula are more than 10,000 light-years away in the southern constellation Pyxis called Compass. The colors seen from the various components more or less ionized in which each emit a wavelength-kind. The colors in this image represent a range of emissions from clouds of the nebula.
Red represents nitrogen, green represents hydrogen, and blue, oxygen. The name "planetary nebula" comes from the first observations of these objects, which sometimes have a circular appearance, like a planet.


In reality it is star reached the end of life, violently expelled in the form of gas, much of the material they are made. The planetary nebula NGC2818 is detached from the surrounding stars. This Hubble image was taken in November 2008 with the WFPC2 instrument (Wide Field Planetary Camera 2).

Image: Source press release Hubble & Gilbert Javaux - PGJ Astronomy Illustration: NASA, ESA, et the Hubble Heritage Team (STScI/AURA)

 Planetary Nebula NGC 2818

Eskimo Nebula or NGC 2392


The planetary nebula NGC 2392 or the Eskimo, was discovered in 1787 by astronomer William Herschel in the constellation Gemini.
NGC 2392 looks like a head surrounded by a parka. This nebula consists of two discs, the inner disk bright enough and the outer disc ring-shaped irregular.
NGC 2392 is at a distance of approximately 4000 years light.
There are only 10 000 years, gas visible on the image below against constituted the outer layers of a sun-like star. The central star is clearly visible in this image.
The internal filaments visible in white were ejected by strong wind of particles from the central star.
The outer disk contains filaments of orange color, a light-year long.


Image: taken by the Hubble Space Telescope in January 2000. One can observe its concentric rings that justifies its name of Eskimo Nebula. His modest apparent magnitude (9.90) can not see with the naked eye, but can be seen with small telescopes. Credit: NASA

 Eskimo Nebula or NGC 2392

Planetary Nebula NGC 6751


Planetary nebulae are simple spheres shaped planet when viewed through a small telescope. But the Hubble Space Telescope is able to show us the details of his celestial objects. Planetary nebulae have spherical shapes varied, are fluorescent balls of gas expelled by a central star at the end of life.
This Hubble image is a composite colored example of a planetary nebula, but with complex characteristics. This image of NGC 6751 was selected in April 2000 to commemorate the tenth anniversary of Hubble in orbit. The colors were chosen to represent the relative temperatures of gas (blue, orange and red, the hottest gas gas coldest).
These are the winds of intense heat and radiation from the central star that create the characteristic shape of nebulae. The central star dying, shines as Suns 9000. It expels its outer gaseous layers and exposes its core burning whose strong ultraviolet radiation illuminates the ejected gas.


The diameter of the nebula is about 0.85 light-years, or about 600 times the size of our solar system. NGC 6751 is 6500 light-years from us in the constellation of the Eagle.

NB: NGC (New General Catalog) is one of the best known catalogs in the field of amateur astronomy with the Messier catalog.

Image: The gas cloud of the planetary nebula NGC 6751 looks like a celestial eye. The dying star at the center and winds eject dust from outer gaseous layers of the star. Credit: Hubble Heritage Team (STScI/ AURA), NASA

 Planetary Nebula NGC 6751

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