Space objects: Galaxies

In one of A.Einstein's statements has told (in 1929): " If to speak fairly, we want not only to learn, how is arranged.. But also whenever possible to achieve the utopian purpose and impudent on a kind - to understand, why the nature is such... In it the prometeus element of scientific creativity " Galaxies will consist began a subject of cosmogonic researches since 20th years of our century when their valid nature has been reliably established and, appeared, that it not fogs, i.e. not clouds of gas and a dust, taking place nearby to us, and the huge star worlds laying from us on very big distances from us. Opening and researches in the field of a cosmology have cleared last decades much of that, as to background of galaxies and stars, a physical condition of the unloaded substance of which they were formed during very far times. In a basis of all modern cosmology one fundamental idea - idea of gravitational instability going back to Newton lays. The substance cannot remain homogeneously absent-minded in space for a mutual attraction of all particles of substance to aspire to create in it condensations of those or other scales and weights. In the early universe gravitational instability strengthened originally very weak irregularities in distribution and movement of substance and during the certain epoch has led to occurrence of strong discontinuities: "pancakes" - protocongestionses. As borders of these layers of condensation shock waves on which fronts originally not rotary, non-whirlwind movement of substance got a whirlwind served. Disintegration of layers on separate condensations too occured, apparently, because of gravitational instability, and it has given rise to protogalaxies.

Many of them appeared quickly rotating due to a whirlwind condition of substance of which they were formed. The fragmentation of protogalactic clouds as a result of their gravitational instability conducted to occurrence of the first stars, and clouds turned to star systems of a galaxy. Those from them which possessed fast rotation, got because of it two-componental structure - in them galaxies, more or less spherical form, and a disk in which there were spiral sleeves where and till now the birth of stars proceeds were formed. Protogalaxies at which rotation was more slowly or at all was absent, turned to elliptic or wrong galaxies.

In parallel to this process there was a formation of large-scale structure of the universe - there were supercongestions of galaxies which, incorporating the edges, formed similarity of cells or beer cells; they managed to be distinguished last years.

In 20-30 of XX century Hubble has developed bases of structural classification of galaxies - huge star systems according to which distinguish three classes of galaxies:

I. Spiral galaxies - are characteristic two rather bright branches located on a spiral. Branches leave or a bright nucleus (such galaxies are designated S), or from the ends of the light crosspiece crossing a nucleus (are designated - SB).

The representative - galaxy M82 in the constellation of the Big She-bear, has no precise outlines, and will consist basically of hot blue stars and gas clouds heated by them. M82 is from us on distance of 6.5 million light years. Probably, about one million years ago in its central part there was a powerful explosion as a result of which it has got the today's form.

Spiral galaxy M51 in the constellation of the Driving Dogs - one of the most surprising spiral star systems. The distance up to them makes about 8 million light years. The thickening on the end of a spiral branch is an independent wrong galaxy. Separate bright stars are in our galaxy.

II. Elliptic galaxies (are designated E) - having the form of ellipsoids.

The representative - a ring fog in constellation of Lyre is on distance of 2100 light years from us and will consist of the luminous gas surrounding the central star. This environment was formed, when the grown old star has dumped gas covers, and they have directed in space. The star was compressed and has passed to a condition of the white dwarf, on weight comparable with our sun, and on the size with the Earth.

III Irregular galaxies (are designated I) possessing wrong forms.

Representatives - Big Magellan the Cloud is on distance of 165000 light years and, thus, is the galaxy of rather small size nearest to us. Near to it the galaxy is located is smaller the Small Magellan Cloud. Both they - satellites of our galaxy.

On a degree of a scrap of branches spiral galaxies are divided on subtypes and, in, with. At first of them - branches are amorphous, at the second - a little scrappy, at the third - very much scrappy, and the nucleus always softly and is not enough. In second half 40th years of XX century U.Baade (USA) has established, that the scrap of spiral branches and their blueness grow with increase of the contents in them of hot blue stars, their congestions and diffuse fogs. The central parts of spiral galaxies yellower, than branches also contains old stars (the population of the second type, on the Baade, or the population of a spherical component) whereas flat spiral branches will consist of young stars (the population of the first type, or the population of a flat component).

The density of distribution of stars in space grows with approach an equatorial plane of spiral galaxies. This plane is a plane of symmetry of system, and the majority of stars at the rotation around of the center of a galaxy remains near to it; cycle times make 10^7 - 10^9 years. Thus internal parts rotate as a firm body, and on periphery angular and linear speeds of the reference decrease with removal from the center. However in some cases taking place inside a nucleus still the smaller nucleolus ("core") rotates fastly. Also the wrong galaxies being also flat star systems similarly rotate.

Elliptic galaxies will consist of stars of the second type of the population. Rotation is revealed only at the most compressed from them. The space dust in them, as a rule, is not present, than they differ from wrong and especially spiral galaxies in which the dust substance absorbing light is present in a plenty.

In spiral galaxies the dust substance absorbing light is present in a lot. It makes from several thousand up to the 100-th share of their full weight. Owing to concentration of dust substance to an equatorial plane, it forms a dark strip at the galaxies which are revolved to us by an edge and looking like a spindle.

Radio-astronomical supervision have allowed to find out in galaxies of a congestion of neutral hydrogen. The weight of it is rather small in spiral galaxies such as Sa, achieves several percent in Sb and reaches 10 % from weight of stars in galaxies Sc, and also in wrong galaxies.

Basically, neutral hydrogen - a body of a gas component of galaxies - is located in a narrow equatorial layer, but separate clouds are observed and is far from it where there are no rather hot stars, capable to ionize it and to result in a condition of a luminescence.

The subsequent supervision have shown, that the described classification is insufficient to systematize all variety of forms and properties of galaxies. So, the galaxies borrowing somewhat intermediate position between spiral and elliptic galaxies (are designated So) have been found out. These galaxies have a huge central condensation and a flat disk surrounding it, but spiral branches are absent. In 60th years of XX century numerous digitiform and disciform galaxies with all gradation of an abundance of hot stars and a dust were open. In 30th years of XX century elliptic dwarfish galaxies in constellations of the Furnace and the Sculptor with the lowest superficial brightness, so small were open, that these, one of the nearest to us, galaxies even in the central part are hardly visible on a background of the sky. On the other hand, in the beginning of 60th years of XX century the set of far compact galaxies from which the farthest are by the form indistinguishable from stars even in the strongest telescopes was open. They differ from stars a spectrum in which bright lines of radiation with the huge red displacement corresponding to such big distances on which even the brightest single stars cannot be visible are visible. As against usual far galaxies in which, because of a combination of true distribution of energy in their spectrum and red displacement look reddish, the most compact galaxies (referring to as also quazostar galaxies) have bluish color. As a rule, these objects in hundreds times are brighter than usual superhuge galaxies, but there are also weaker. At many galaxies the radio emission of not thermal nature arising, according to the theory of the Russian astronomer is revealed I.S.Shklovsky, at braking in a magnetic field of electrons and heavier charged particles moving with speeds, close by the speed of light (so-called sincrotron radiation). Such speeds of a particle receive as a result of grandiose explosions inside galaxies.

The compact far galaxies possessing a powerful not thermal radio emission, refer to as N-galaxies.

Star-shaped sources with such radio emission, refer to as quasars (quazostar radiation sources), and the galaxies possessing a powerful radio emission and having the appreciable angular sizes, - radiogalaxies.

All these objects are extremely far from us, that complicates their studying.

The radiogalaxies having especially powerful not thermal radio emission, possess mainly elliptic form, meet also spiral.

The big interest is represented with so-called Seifert galaxies. In spectra of their small nucleus there are many very wide bright strips testifying to powerful emissions of gas from their center with speeds, km / sec achieving some thousands. At some Seifert galaxies very weak not thermal radio emission is revealed. Optical radiation of such nucleus, as well as in quasars is possible, as, is caused not by stars, and also has not thermal nature. It is possible, that a powerful not thermal radio emission - a temporary stage in development of quazostar galaxies.

Radiogalaxies close to us are investigated more full, in particular by methods of optical astronomy. In some of them features not explained up to the end are found out for the present. So, in an elliptic galaxy of Cent And extraordinary powerful dark strip along its diameter is found out. One more radiogalaxy will consist of two elliptic galaxies, close to each other and connected by the crosspiece consisting of stars.

At studying wrong galaxy M82 in constellation of the Big She-bear the American astronomers A.Sandzh and T.Linds in 1963 came to the conclusion, that in its center about 1,5 million years ago there was a grandiose explosion as a result of which in all sides with a speed about 1000 km / sec jets of hot hydrogen have been thrown out. Resistance of the interstellar environment has prevented distribution of jets of gas to an equatorial plane, and they proceed mainly in two opposite directions along an axis of rotation of a galaxy. This explosion, apparently, has generated also set of electrons with the speeds close by speed of light which were the reason of not thermal radio emission.

Long before detection of explosion in M82 for an explanation of other numerous facts the Soviet astronomer V.A.Ambartsumjan has put forward a hypothesis about an opportunity of explosions in nucleus of galaxies. In his opinion, such substance and now is in the center of some galaxies, and it can share on a part at explosions which are accompanied by a strong radio emission.

Thus, radiogalaxies are galaxies at which nucleus are in process of disintegration. The thrown out dense parts, continue to divide, probably, form new galaxies - sisters, or satellites of galaxies of smaller weight. Thus speeds of scattering of splinters can achieve huge values. Researches have shown, that many groups and even congestions of galaxies break up: their members beyond all bounds leave from each other as though all of them have been generated by explosion.

The reasons of formation of the so-called cooperating galaxies which have been found out in 1957-58 by Soviet astronomer B.A.Vorontsov - Viliaminov are not explained still also. These are pairs or close groups of galaxies in which one or several members have obvious distortions of the form, appendages; they are sometimes shipped in the general luminous fog.

Such thin crosspieces connecting a pair of galaxies, and the "tails" directed away from the next galaxy, as though pushed away are observed by it. Crosspieces sometimes are double, that testify that distortions of forms of cooperating galaxies cannot be explained by the tidal phenomena. Frequently the big galaxy of one of the branches, sometimes deformed, incorporates to the satellite. All these details, similarly to galaxies, will consist of stars and sometimes a diffuse matter.

Frequently galaxies meet in space in pairs and larger groups, sometimes as the congestions containing hundreds of galaxies.

Our galaxy with Magellans Clouds and with other nearest galaxies make, probably, also a separate local congestion of galaxies. Magellans clouds and our galaxy, apparently, are shipped in the general for them a hydrogen cloud. Groups and congestions are various as galaxies included in them. Sometimes into them enter only spiral and wrong, sometimes - only elliptic galaxies, sometimes - both those, and others. The nearest to us are the unloaded cloud of galaxies in the Big She-bear and wrong congestions in constellation of Deva. Both contain galaxies of all types. Very rich and compact congestion of galaxies E and So, taking place in constellation of Hair of the Veronica, totals thousand members. Luminosity and the sizes of galaxies are rather various.

Galaxies - supergiants have luminosity, in 10 times the Sun exceeding luminosity, quasars on the average in 100 times are brighter; weakest of known galaxies - dwarfs are comparable to usual spherical star congestions in our galaxy. Their luminosity makes about 10 luminosities of the sun.

The sizes of galaxies are rather various and change from tens parsec up to tens thousand parsec.

The space between galaxies, is especial inside congestions of galaxies, apparently, contains sometimes a space dust. Radiotelescopes do not find out in them appreciable amount of neutral hydrogen, but space beams, penetrate it through the same as and in electromagnetic radiation.

It is known about 1.5 thousand bright galaxies (up to 13-th star size). " The morphological catalogue of galaxies " (which will consist of four volumes), contains data on 30 thousand galaxies more brightly 15 star sizes. They cover 3/4 all skies. 5 - some billions galaxies up to 21 - star size are accessible to a meter telescope. Such galaxies differ from the weakest stars only easy dim images.

The galaxy will consist of set of stars of various types, and also star congestions and associations, gas and dust fogs and separate atoms and particles, absent-minded in interstellar space. The most part of them borrows volume of the lensformed form with a diameter about 30 and thickness about 4 kiloparsec (accordingly about 100 thousand and 12 thousand light years). The smaller part fills in almost spherical volume with radius about 15 kiloparsec (about 50 thousand light years).

All components of a galaxy are connected in the uniform dynamic system rotating around of a small axis of symmetry. To the terrestrial observer who is taking place inside a galaxy, it is represented as the Milky Way (from here and its name - "Galaxy") and all set of the separate stars seen in the sky.

Stars and an interstellar gas-dust matter fill in volume of a galaxy non-uniformly: they about a plane are most concentrated, a perpendicular axis of rotation of a galaxy and by a making plane of its symmetry (a so-called galactic plane). Near to a line of crossing of this plane with heavenly sphere (galactic equator) the Milky Way which average line represents almost big circle as the Solar system is near to this plane also is seen. The Milky Way represents a congestion of huge amount of the stars merging in a wide whitish strip; however, the stars projected in the sky by a number, are removed from each other in space on the huge distances excluding them of collision in spite of the fact that they move with the big speeds (tens and hundreds in km / sec) in a direction of poles of a galaxy (its North Pole is in constellation of Hair of the Veronica). The total of stars in a galaxy is estimated in 100 billion.

Interstellar substance dimmed in space also not in regular intervals, concentrating mainly near to a galactic plane as the globulas, separate clouds and fogs (from 5 up to 20 - 30 parsec in a diameter), their complexes or amorphous diffuse formations. Especially powerful, is relative dark fogs close to us are represented a naked eye as dark glades of wrong forms on a background of a strip the Milky Way; deficiency of stars in them grows out absorption of light by these not luminous dust clouds. Many interstellar clouds are covered by stars of the big luminosity close to them and are represented as light fogs, as shine or reflected light (if will consist of space motes) or as a result of excitation of atoms and the subsequent emission of energy by them (if fogs gas).

Our days with good reason name the Golden Age of astrophysics remarkable and more often unexpected opening in the world of stars follow now one by one. The solar system became last time a subject direct experimental, and not just observant researches. Flights of interplanetary space stations, orbital laboratories, expeditions on the Moon have brought set of new concrete knowledge of the Earth, circumterraneous space, planets, the Sun. We live during an epoch of amazing discoveries. The most improbable imaginations are unexpectedly quickly realized. For a long time people dreamed to solve secrets of the Galaxies scattered in boundless open spaces of the universe. It is necessary to be amazed only how quickly the science puts forward various hypotheses and there and then them denies. However the astronomy does not cost on a place: there are new ways of supervision, are modernized old. With the invention of radiotelescopes, for example, astronomers can glance on distances, which else in 40-x. Years of XX century seem inaccessible. However it is necessary to itself to present clearly huge size of this way and those enormous difficulties, with which else it is necessary will meet on a way to stars.