Space is often called the airless space, believing it empty. However, it is not. In interstellar space is dust and gas (mostly helium and hydrogen, the latter much more). In the Universe there are whole cloud of dust and gas. These clouds we do not see the center of our Galaxy. Of these clouds can have dimensions in hundreds of light years, and part of them can be compressed under the influence of gravitational forces.

During the compression part of the cloud will be compacted, decreasing in size and at the same time heating up. If the mass is shrinking substances sufficient to in the compression process inside it started to happen nuclear reactions, some of this cloud is obtained star.

It should be noted that usually from one cloud born a group of stars called the star cluster. In this cloud formed a separate seal (we also will continue to call the clouds), each of which can create a star. As mentioned, the lightest stars have a lot to 12 times smaller than the Sun. If compressible cloud less massive, but not inferior to the Sun in the mass of more than a hundred times, these clouds form the so-called brown dwarfs. Brown dwarfs even colder red stars. These objects is quite warmed up by the forces of gravitational compression and emit a lot of heat (infrared radiation), and glow barely. But nuclear reactions in brown dwarfs do not begin. In the end, gravitational compression stops gas pressure inside, cease to be allocated new portions of energy, and brown dwarfs in a relatively short period cool down. One of the last open a brown dwarf is a dwarf in the constellation Hydra, his brilliance is only 22,3, although he was removed from the Sun by only 33 light years. The nearest uniqueness of this brown dwarf is that all previously opened such objects included in the binary system, and this is single. Noticed it only due to its proximity to the Earth. Planet Jupiter, the largest in the Solar system, 80 times lighter than most low-mass stars and only 8-10 times lighter brown dwarfs. Again notice the role of the mass of the object in its own destiny.

If massive enough to form a star, the cloud is so heated that begins to actively radiate warmth and may be poorly lit red color (before the start nuclear fusion), the cloud made already be called a protostar (up-star). As soon as the temperature in Central protostar will reach 10 000 000 To, nuclear fusion begins. Compression protostar stops by the pressure of light, it becomes a star. Again, from the mass depends how quickly protostar will become a star. Stars like the Sun spend on this stage of his birth 30 000 000 years of age, star in three times more massive - 100,000 years, and in ten less massive - 100 000 000 years. So, amassive stars do everything slowly, and are born and live. As we remember, so light the stars are red stars, which are small and are called red dwarfs. Red dwarfs ten times less than the Sun. Style star of the Sun is called the yellow dwarf, such stars are also relatively small. The most heavy and large normal stars are called blue giants.

Young star is still surrounded by its parent cloud, which is in the form of a gas or gas-dust disk rotates around it. This stellar wind - the stream of various particles spewing from the surface of stars with high velocities, pressures on the material of the cloud, trying to push him away. As the cloud was flat disk, the motion of particles in its plane under the pressure of the stellar wind difficult. The substance is directed along the axis of rotation of stars and clouds, in two opposite directions. In these areas substances little, and particle clouds almost unimpeded plunged away from the star. It formed often seen outflows of substances by young stars.