They say that the stars are going out at dawn and light up the evening, but at night, when our atmosphere is transparent to visible light and scattered sunlight to create a bright blue background, the stars Shine just like Shine to our ancestors millions of years ago. And yet the stars are not eternal, they go out for real.

In the sky simultaneously visible stars of different ages: some are lit, others are damped. The most massive live only millions of years, and the stars of small masses survive up to several billion years.

Everything that determines their mass, and therefore gravity. In the depths of the stars, thermonuclear reactions occur, resulting in increased temperature and generates a high gas pressure. Gas pressure, struggling with gravity, keeps the star in equilibrium. When you turn a new reaction, the equilibrium is disturbed: more compressed, compacted and heated, and the atmosphere swells up and cools down slowly. The star turns into a red giant.

In stars with a mass of order the mass of the Sun (in this article, we consider only them) the atmosphere, expanding, pulsing, breaks away from the nucleus and continuing to expand, it turns into a planetary nebula. This is another failed historically the term: planetary nebula have nothing to the planets. Their spherical structure when observed in a small telescope resembled a planetary disk, but the origin remained a mystery. An academician, was the first to realize that planetary nebulae and their nuclei white dwarfs red giants originate from.

With the relatively cold surface of the red giant slowly expires on the substance (stellar wind). From the hot core of the star “blow” is much more energetic winds. They catch up with the flaring atmosphere with its stellar wind, “rake up” the gas, forming around the core more dense spherical shell planetary nebulae.

As the kernel is very hot, a maximum of its radiation falls in the ultraviolet. The shell atoms emit the received energetic quanta in quanta of visible range, and so planetary nebulae are much brighter than their nuclei. The farther from the nucleus, the nebula is colder.

Spectrum of the nebula continuous line radiation. The inner layers of the planetary nebulae radiate in the lines of the ionized elements: helium, carbon, oxygen, nitrogen and others. Especially there are two green lines nobelium. They could not be identified and attributed to a nonexistent chemical element, as if the peculiar nebulae, nebulas. It turned out that it’s forbidden lines of double ionized oxygen, which appear only in a very rarefied gas; these conditions occur in nebulae, including planetary.

Further from the core, the gas becomes neutral, then formed molecules. Their lines in the spectra of planetary nebulae can be observed with ground based radio telescopes. Further, where it is much colder, the molecules are combined in the dust. It showed observations in the infrared spectral region, carried out on spacecraft. Planetary nebula one of the main suppliers of dust in the interstellar medium.

A planetary nebula is slowly and gradually climbing using a rate of tens of thousands of km a minute and little by little, around tens of thousands of thousands of tens of thousands of years, even sprinkled from the interstellar distance.

Planetary nebula white dwarf the center of the previous celebrity that’s stopped atomic consequences. The fever thousands of countless hours, the density attained a million tons each cubic centimeter as it shrunk into the magnitude of the planet. Under those states, the chemical of this nucleus gets electron ion plasma.

Even the bigger that the extent of the white dwarf, the larger the density, the more the more waves tightly approach each other. The larger the density, the more greater, as stated by the Pauli principle, the more the more typical power of the electrons along with their normal rate. The strain generated from the electrons gasoline, interrupts gravitational compression, also a celebrity for years and years accelerates equilibrium. Even cooling, a white dwarf isn’t compressed, so since the rate of electrons currently will not rely on the temperatures, and also depend just on the density of this chemical.

Thus, the pressure of gravity onto its own floor is huge. Within their detected spectra traces of hydrogen and helium, aspects which have burnt out from these celebrities. As it happens that white tape placed to the compound of this interstellar medium. Additionally, the variety traces have been displaced at the long wave facet as “gravitational redshift” emitted photons, escaping out of strong fibrous areas shed a few of these electricity.

Radiation white dwarfs even at rather large surface temperatures is tens of thousands of times less radiation in sunlight due for their limited dimensions. Radiating kept in center electricity, white windmills are still exist for a lot more centuries. Gently warming, they get yellowish, reddish, dark. Their fever is near to nearby temperatures, roughly 10 To, thus from the optical variety, they ceased to radiate.

Outstanding Indian scientist, Nobel laureate, Chandrasekhar ascertained that the top limit of bulk in that white sands stay secure 1.46 legends of their solar.

When substantial populations of leading cores, the rate of electrons means that the rate of lighting. From the brand new bodily states of white dwarfs incapable of hold out against the forces of gravity which disrupts them into the magnitude of just tens of thousands of km. For neutron stars, there’s a limitation to the bulk which may withstand gravity.

But if the mass exceeds this limit, then gravity ceases to be, creating a counter to her power, and turns the former star into a black hole.

Invisible remnants of stars whose mass is concentrated in a small volume, we have a huge gradient of the gravitational field. The acceleration due to gravity in white dwarfs is of the order of thousands of kilometers per second, per second! Neutron stars much more. They represent a great danger to future space ships: can tighten and how to escape? While it is impossible to imagine.