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What a supernova?

 Automatic translation  Automatic translation Updated June 01, 2013

A supernova is visible phenomenon, directly from the cataclysmic explosion of a star that leads to its destruction and thus the death of the star. This explosion is accompanied by massive increases its brightness as seen from Earth, which can last up to several weeks and even months. It is visible in daylight and at night it can be as bright as the moon and even give a shadow to objects. A supernova appears so often as a new star, hence its name, nova. Supernovae are rare events in our Milky Way, about one to three per century, against the scale of the Universe we observe every day. It was during the supernova explosion the star releases the chemical elements, it was synthesized in its existence and during the explosion itself. The shock wave from the supernova favors the formation of new stars, accelerating the contraction of regions of gas and dust in the interstellar medium. The novas, unlike supernovae come from thermonuclear explosions, causing a partial destruction of the star by expelling part of its surface into interstellar space. Our sun will not end his life as a supernova but much quieter.
The death of a star can be mild or severe, depending on its mass. Below 1.4 times the mass of the Sun, the star goes out in peace, it will pass the size of a red giant (about 50 million km radius) to that of the Earth (about 6 000 km radius). The star becomes a white dwarf. Between 1.4 and 5 times the mass of the Sun, his agony is much more violent.


Its radius shrinks to 10 km The final density is enormous, the nuclei can not resist and the heart of the star becomes a giant nucleus of neutrons. The collapse caused a terrible explosion, which will project the upper layers of the star into space and it will shine in the sky, a supernova. Above 5 times the mass of the Sun, the collapse is extremely violent. It can not be stopped. The heart of the star becomes a black hole.
The violence of the collapse produces a huge explosion, which projects the upper layers of the star into space. As in the previous case a supernova will spread, hundreds of billions of miles, seeding the interstellar medium of heavy elements produced during the life of the star during the explosion. These heavy elements are the building blocks of terrestrial planets like Earth.
This new Hubble image, is one of the most important images ever produced with an observatory in Earth orbit. It shows us a full and very detailed, the Crab Nebula. The Crab is arguably the most interesting subject, and also one of the most studied in the world of astronomy. The image of this nebula is the largest image ever taken with Hubble camera.
It was assembled from 24 individual exposures taken by the Hubble NASA / ESA Hubble Space.

Image: List of the supernovae

 nébuleuse du crabe

Image:  The most famous supernova of the history of the astronomy. SN 1054 is a supernova the explosion of which was seen since the Earth from July 4th, 1054, called misty of the crab today which is situated in our galaxy in the constellation of the bull.

Stellar explosions in NGC 6984


Supernovae are extremely luminous explosions of stars, so bright they are remarkable among the stars shining like a spiral galaxy NGC 6984. In the picture below you can see against near the center right, a very bright star that shows the end of its life in a spectacular explosion. Already in 2012, the star named SN 2012im expelled much of its material in the middle of the spiral galaxy NGC 6984 arm. And in 2013 it was the turn of SN 2013ek another supernova explodes in this galaxy. It is it which is visible in the foreground of this picture, as a very bright star just above and right of the center of the galaxy.
SN 2012im was a Type Ic supernova, while the more recent SN 2013ek is a type Ib. They are both, supernovae resulting from the collapse of their core who have lost their outer layers of hydrogen. However, the supernova SN 2013ek type Ib lost more, its outer layers of helium. This image was taken August 19, 2013, very close to where SN 2012im exploded, so close that the two events are thought to be linked.


Two independent supernovae same class, which explode a year apart is a very unlikely event. It was initially believed that SN 2013ek was a revival of SN 2012im, but other observations showed that they were well separated, although they may be closely related by an unknown cause.

NB: Supernovae of type II, Ib and Ic are stars at the end of life. Type II supernovae have a spectrum that contains hydrogen, while Ib and Ic supernovae type are stars who have already used up their hydrogen, so it does not appear on their spectrum. Type Ic supernovae have also exhausted their helium and does not appear in the spectrum.

Image:  The supernova SN 2013ek that can be seen near the center right of the spiral galaxy NGC 6984 is an extremely bright star that announces the end of its life in a spectacular explosion. Image Credit: NASA / ESA / Hubble.

 Explosion 2013ek supernova in the galaxy NGC 6984

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