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.
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.
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.
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.
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).
Nebula Dumbbell or M57
In 1764, the French astronomer Charles Messier described this magnificent cloud cosmic as an oval nebula without star.
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
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 brilliant red circle situated in the center is the light of a disk of dust surrounding the white dwarfish star.
Image: The Helix nebula or NGC 7293 seen by the spatial telescope Spitzer
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.
Image: The Cat's Eye Nebula or NGC 6543 seen by the spatial telescope Hubble
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.
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)
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.
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
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.
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.
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