Stars of the greater mass of end their life otherwise. Helium nucleus of such stars, compressed, heated. It begins synthesis of carbon, forming carbon core. It also shrinks begins, the larger heating, synthesis of oxygen, etc. In the end, the star begins to resemble a bulb in the middle of which, at the last stage of the chain reactions Matures iron-Nickel core, in which no reaction to go can't do it anymore, that is formed white dwarf.

But this white dwarf increase in mass, as the reaction in the overlying layers continue. When the dwarf reaches a mass of 1.4 solar, pressure electron gas cannot dwarf to keep the forces of gravity. Electrons are pressed into protons, forming neutrons, which seamlessly converge (protons was not allowed to approach the power of electrostatic repulsion, and neutrons, recall that the charge does not have). In the second dwarf decreases the size of the Earth up to 10(!)km Almost reaching the density of nuclear matter, dwarf abruptly stops shrinking.

The substance of such density his inner pressure (here participate special nuclear repulsive forces) once again for the life of the star stops gravity. The outer layers formed neutron star for a moment still continue to fall by inertia to the heart, increasing the pressure, resulting in the emergence of shock waves and release in the outer layers of the star huge number of neutrinos. This resets the outer layers, to the grandiose explosion, the energy of which is comparable with the energy emitted by the whole galaxy! Such an explosion called a supernova explosion. In the process of dissipation in the space of the upper layers of the star, its brightness falls, supernova fades away, and the place of flash, you can see her balance - expanding nebula.

This figure shows the development of the fate of our three stars. About the expanding supernova explosion planetary nebula in the form of a ring, generated by the lower a star: yellow stars "ripen" later than blue. Upper red namasivaya asterisk will Shine without disasters, until after many billions of years, too, will not generate a planetary nebula.

The expanding gas supernova explosion also can then log in to the cloud, where born, another star. Only in this cloud will not only helium and hydrogen, but also other elements, formed at the last stages of life of the first stars and during its explosion. One of the stars "second generation" is our Sun.

In the center of the explosion remains extremely hot neutron star with a size of several kilometers. If from the star after the explosion are still a lot of substance, so that its weight is more than three times that of the sun, instead of a neutron star can produce amazing object is a black hole. The force of gravity at its surface is so high that it cannot leave even light. The properties of these stars are very complex, their study is theoretically the most complex mathematical means. To see the same black hole cannot - as mentioned, it does not produce light, even the most high-energy photons. Holes such objects are called is because all too closely approached him, inevitably falls on the surface, and nothing can leave. All the matter as if lost in a black hole forever. The initial mass of the star, which in the end will turn out black hole, 30 and more times exceed the mass of the Sun. Very frequent formations black holes are in double stars, the evolution of which is read on the next page.

Neutron stars and black holes are combined into one class of stars, referred to as the relativistic. The properties of these objects can be described by the laws of relativistic physics.

Putting the point in this part of the story, we emphasize once again the dependence of the fate of the heavenly bodies from their mass, indeed the main characteristics of objects in the Universe. Amassive stars end their life, becoming white dwarfs and dissipating into interstellar space, its outer layers. It formed a planetary nebula. Massive stars, covering the whole range of nuclear reactions, break out the supernova explosion, which is the formation of a nebula of another type. In the center of the explosion remains a neutron star or a black hole, to explain the properties of which are taken only the most modern physics. And so many contributes to the existence of double star systems.