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Nebulas

Nebula of the eye of cat or NGC 6543

category : nebulas

The nebula of the eye of cat (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.

The nebula of the eye of the cat or NGC 6543 seen by the spatial telescope Hubble

Nebula of the red square or MWC 922

category : nebulas

Situated about 5000 light years in the constellation of Ophiucus, still called Secretary bird, MWC 922 indeed shows a stunning symmetric structure in the form of square, when she is observed with the telescope of the Mountain Palomar and that of Keck.
The combination of both observations in infrared close (1,6 microns) shows in fact, under a certain angle, two conical cavities constituting a bipolar nebula produced by the ejection of matter from the superior layers of an unstable star.
The regularities, that we can observe associates in this biconic structure, are can be due to periodic waves propagating inside a disk of matter orbiting around the star, according to the astrophysicists.
How come that this nebula has a square shape? The hypothesis which privileges the birth of the square nebula would want that the central stars expelled cones of gas. In the case of MWC 922 seen since the Earth, these cones would have practically been in right angle and seen each other by the side.
The researchers suppose that cones seen under another angle would appear under the same shape as the gigantic rings of supernovae 1987A.

The nebula of the red square or MWC 922 seen by the telescope of the Mountain Palomar in California and the telescope Keck 2 of Mauna kea in the Hawaiian Islands

Nebula NGC 3603

category : nebulas

The huge nebula NGC 3603 accommodates within it, thousands of young glittering stars. This magnificent stellar panorama is one of the most massive heap of young stars of the Milky Way. NGC 3603 is an active nursery of formation of stars situated in the arm of the Hull of our Galaxy, in approximately 20 000 light years of our Solar system.
The image opposite of the telescope Hubble shows a heap of young stars surrounded by a vast region of dusts and gas.
The intense ultraviolet radiation and the solar winds of the most blue and the warmest stars inflated a big bubble around the heap.
The movement in the nebula of these winds of radiations formed big dark zones in the nebula.
These gaseous regions which extend over several light years, are directed to the center of the heap. We observe dark clouds in heap, called globules de Bok A globule of Bok is a dark heap of dusts and gas of the interstellar middle within which the birth of stars can begin. , visible in the right superior corner.
These clouds are constituted by dusts and by dense gases and are approximately 10 - 50 times as massive as the Sun.
A globule of Bok can undergo a gravitational collapse and lead to the formation of new stars. Most of the stars of this photo, are young very warm, visible stars in blue.

They emit ultraviolet radiations and violent winds which dig sorts of cavities in the gas and the dust which surround them The nebula NGC 3603 was discovered by John Herschel in 1834. The image covers approximately 17 light years and was realized on December 29th, 2005 with the instrument ACS (Advanced Camera for Surveys).

A nursery activates of stars within the nebula NGC 3603 (shots of the spatial look-out observatory Hubble).

Sharpless 171

category : nebulas

Sharpless 171 is a nebula, of dusts and dense and cold gas, which accommodates within it, thousands of young glittering stars.
This region of formation of star in about 3000 light years of us is situated in the constellation of Cepheus. This region of formation of stars is 171eme of the catalog of nebulas in emission, created in 1959 by the astronomer Stewart Sharpless.
They are the warm stars of the heap of stars, Berkeley 59 which supply the energy which makes brilliant, the nebula Sharpless 171.

 

This heavenly landscape shows us the diffuse emission some atomic gas thanks to the use of a filter to narrow band and to a subtle coding of colors.

credit & copyright: Antonio Fernandez

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Astronomy - October 15, 2007