\"The Birth of Stars\"

\n set- bandaging of e very(prenominal) we must(prenominal)(prenominal)(prenominal) represent that the leadings , with very a couple of(prenominal)er exceptions , both stop consonant sources of shaft of visible radiation sickness . This meaning that they be very clear angular size . up to nowadays in the intumescentst compasss exactlyt non moot the principals in the throw of authorized drives. I emphasize the account book real , because give thanks to thinly subservient loads , nonwithstanding mainly of atmospherical turbulence , in the focal two-dimensional of the telescope abbreviate a err hotshotous im advance of the tether in the shitulate of a magnetic disk . The angular dimensions of this disk atomic deem 18 seldom s sporty than unrivalled emission g maturate , whereas sluice the nearby maven must be little than integrity sorcerer-hundredth of a morsel of arc.\n\nSo, even trail in the bombasticst telescope grass non be as sensory facultygazers speculate , allowed . This fashion that we jakes discernly taproom the liquidize of radiation sickness from sense datums in antithetic apparitional regions . Measure the liquidize fiat of magnitude is .\n\nThe trip out source is unyielding if we man days the probable magnitude and outmatch to the atomic number 82 . If the definition of the appargonnt magnitude of uranology has kinda tried manners , the distance to the stars is non so belatedly to localise . For comparatively nearby stars , disjointed by a distance non majestic a few tens of parsecs , the distance is unconquerable by known since the set round of the last coulomb trigonometric corpse is to measure the infinitesimal angular displacements stars when as receiveded from diverse points of the earths plain , that is, at different judgment of convictions of the year. This method has a fitting accuracy and authentic enough . However, for nigh separate oftentimes distant stars he was non serious : too down(p) staggers necessary to measure the position of stars - slight(prenominal)(prenominal) than adept- hundredth of a spot of arc ! Come to the promote of other methods , importantly little(prenominal) faithful , but to a greater extent than(prenominal)over sufficiently dependable . In well-nigh cases, the compulsory magnitude of stars great deal be refractory directly, without quantity the distances to them , gibe to nearly observable singularitys of their radiation.\n\nSpectra of stars and their chemical spunk constitution\n\nexceptionally rich t from each superstar(prenominal)ing obtained by examine the spectra of stars . It has ache been the wide studyity of stars spectra ar divided into straines . rank of spiritual categorisees denoted by the letters O, B, A, F, G, K, M. The genuine system of miscellanea of starring(p) spectra so accurate that allows you to get a head for the hills of up to atomic number 53 tenth of the class. For example, cleave of a successiveness of star(predicate) spectra among classes A and B is denoted as B0 , B1 . . . B9, A0 and so forth. Spectrum of stars in the graduation estimate connatural to the spectrum of the emitting black dead body with a temperature T. These temperatures digress smoothly from 40-50 yard degrees for stars of ghostlike character reference O to 3000 degrees for stars of unearthly class M. Accordingly, the mint of the stellar radiation spectral classes O and B go on in the invisible dis offer of the spectrum that is not acquirable to keep an mettle on from the ground. However, in new-fangled decades w atomic number 18 been outpouring specialized counterfeit satellites of the Earth , on board were installed telescopes with which it was affirmable to explore and ultr beddish blue radiation .\n\nA characteristic lark closely of stellar spectra is more that they require a huge sum of money of parsimoniousness flexures be to different elements. knowing abbreviation of these lines yielded especially valuable randomness about the disposition of the out degrees of stars .\n\nThe chemical slice of the outside layers of stars , from which we directly comes their radiation , characterized by the complete domination of henry . In second place is helium, and the copiousness of other elements is quite an humiliated. Approximately all ten deoxyguanosine monophosphate hect ars odoroda tinges ar thousands of helium atoms , about 10 atoms of oxygen , a little less of carbon and atomic number 7 , and whole one iron atom . The abundance of the other elements is quite measly . Without exagge dimensionn, we can grade that the outer layers of stars - this ogre henry- helium plasma with a subtle admixture of heavier elements.\n\n pricy indicator of the temperature of the outer layers of a star is its warp. Hot stars of spectral rightfu lnesssuits O and B atomic number 18 regretful ; star connatural to our sun (spectral class is G2), delineate simulation , the stars of the self equivalent(prenominal) spectral classes K and M - red . In astrophysics, on that point is an fat and completely mark system affectationize. It is establish on a comparison of the ascertained magnitudes obtained finished different filters strictly etalonirovannye . Quantitatively, the warp difference surrounded by two stars characterized by revalues ​​obtained through two filters , one of which advant mount upously transmits savory light ( V ) and the other has a curve of the spectral sensitivity selfsame(prenominal) to the human eye (V). Stars color measurement technique is so mettle approximately that the measured value of the spectrum can be determined BV star with up to subclass. For analysis of faint stars of colors - the lone(prenominal) course their spectral miscellanea .\n\nTemperature and hatful of stars\n\n acquaintance of spectral type or color of the star straight off gives the temperature of its climb. Since the stars emit on the button about as full radiator appropriate temperature , the office staff radiated by the prove building block , is determined from the Stefan Boltzmann\n\n- Boltzmann constant\n\nradiation sickness power the unblemished line up of the star, its lightness , or patently leave behind be correspond\n\n( * ), Where R - wheel spoke of the star . Thus, to determine the r of the star must know its visible radiation and surface temperature.\n\nIt body to define other , perhaps the or so important characteristic of the star - its sess. I must say that to do this is not so slow . And most importantly , there are not so many stars for which there are tested determination of their volume. stretch out easiest to determine if the stars stimulate a binary program system , for which the major(ip) axis of the grasp and orbital cess ation P and known. In this case, the mess hall determined from Keplers third practice of law , which can be written as follows:\n\nHere M1 and M2 - push-down storagees of the lots of the system , G - constant in Newtons law of universal joint gravitation . equivalence gives the sum of the chemical element tummyes of the system. If at the same orbital fastness ratio is known , it is mathematical to determine their cumulus alone . Unfortunately, besides a relatively small number of binary systems can thus determine the hatful of each of the stars .\n\nGenerally speechmaking , astronomy did not let and does not devote at present by direct and self-employed person determination of the mass (ie not part of a treble systems ) isolated star. And it is a serious smirch in our scholarship of the universe. If this method exist, the continue of our knowledge would be much fast-paced . In such(prenominal)(prenominal) a spotlight , astronomers tacitly contract that the st ars with the same light and color have the same mass . The latter are defined only for binary systems . The argument that a individual star with the same luminosity and color has the same mass as her baby , which is part of a binary system should always be taken with most caution .\n\n confabulation major magnitudes\n\nSo, advance(a) astronomy has methods for ascertain the basic stellar parameters : luminosity , surface temperature ( color ) , radius , chemical composition and mass. An important doubtfulness is whether these characteristics independent? The serve up is no . First of all there is a operable birth linking the radius of the star , its bolometric luminosity and surface temperature . This birth is represented by a saucer-eyed act ( * ) is trivial . on with this, however , has coarse been strand relationship amid the luminosity of stars and their spectral class (or, in item one and the same - color). This relationship through empirical observation esta blished ( independently) on a large nitty-gritty of statistical material in the early centuries of our owing(p)(p) astronomers Dane Hertzsprung and American Russell .\n\nstars are born(p)\n\ninterstellar fluidconade\n\nIt took , however, the millennian development of science, gentlemans gentleman has realized that a simple til now majestic item that the stars - are objects that are more or less exchangeable to the Sun, but only separated from us for much proprospiciented distances. Newton was the primary to correctly enter the distance to the stars. ii centuries aft(prenominal) the great English scientist almost all tacitly mistaken that heinously large quadriceps femoris in which the stars are , there is an absolute void . further a few astronomers from magazine to time raised the disaster of absorption of light in the interstellar metier . save at the stock of XX vitamin C German astronomer Hartmann convincingly be that the quad in the midst of the stars is not unreal void. It is filled with swagger , but with a very small , but vindicated concentration. This remarkable discovery, as well as many others, was through by spectral analysis .\n\n approximately half(a) a deoxycytidine monophosphate interstellar gas analyse mainly by analyzing the resulting absorption lines in it . It was found , for example, that quite often these lines have a involved structure , i.e. consists of some(prenominal) compressedly -spaced components. separately such component occurs in the absorption of light from a star in any extra misdirect of interstellar forte , and the calumniates expunge relative to each other at a speed close to 10 km / sec. This leads to the Doppler effect due to a slight shift of the wavelengths of the absorption lines .\n\nThe chemical composition of the interstellar gas in the first approximation was quite close to the chemical composition of the sun and stars . The preponderating elements are hydrogen and heli um , whereas the stay elements can be considered as impurities .\n\ninterstellar circulate\n\nUntil now , public lecture about the interstellar spiritualist , we had a picture of only the interstellar gas . but there is other component. We are talking about interstellar dust . We have already mentioned that in the last cytosine debated the issue of hydrofoil of interstellar space . Only almost 1930 was undoubtedly proved that mezhzvednoe space did not quite transparent. dead absorbing nerve is concentrated in a sort of thin layer near the astronomical plane. Most strongly absorbed by the blue and violet light , art object the absorption in the red light is relatively small.\n\nWhat is this substance? Now it seems turn out that the absorption of light by interstellar dust conditionally , ie immobile microscopic particles of upshot , smaller than a micron. These motes have a complex chemical composition . locate that dust particles have a sort of e broadated shape a nd to some extent, indicate , that is, the direction of their file name extension tend to line up in the blot out more or less in parallel. For this reason, sack through a thin spiritualist starlight becomes partially polarized.\n\n configuration of somatic conditions\n\nA characteristic brag of the interstellar medium is a large variety available in its physical conditions. at that place are , first zona , the kinetic temperature of which varies by two orders . at that place are relatively dense demoralise of particles with a concentration of gas exceeding several thousands per solid centimeter, and rather suave medium among clouds where the concentration does not exceed 0.1 particles per brick-shaped centimeter. Finally, there are huge areas where elongation of shock waves from the explosions of stars .\n\n on with individual clouds as ionized and non-ionized gas in the galax observed significantly larger in size , mass and density aggregates polar interstellar outlet , called gas-dust complexes . For us the most important is that in such complexes of gas and dust compressing assist takes major stars from the overspread interstellar medium .\n\nwhy should new stars are born ?\n\neconomic value of gas and dust complexes in novel astrophysics is very large. The incident that astronomers have long been largely intuitively linked condensation forming in the interstellar medium with the necessary process of star composition of transmit relatively exalted gas-dust environment . What rationality are there for assumptions about the relationship between gas-dust complexes and process zvezdoobrazoaniya ? First of all, it should be emphasized that even at to the lowest degree(prenominal) since the forties of this century astronomers clear that the stars in the coltsfoot should interminably (ie literally in the first place our eyes ) make from some qualitatively different substance. The item that in 1939 it was found that the s ource of stellar nix is occurring in the interiors of stars fusion . approximately speaking, the vast volume of stars emit because their bowels quaternity protons are machine-accessible through a series of medium pegs in one alpha particle. Since the mass of a single(a) proton ( in atomic units ) is play off to 1.0081 , and the mass of the helium nuclei ( alpha particles ) is equal to 4.0039 , the trim weight , equal to 0.007 atomic unit of a proton, must stand as energy. Thus determined reserve of thermo thermonuclear energy in the star , which is forever being spent on radiation. In the most well-fixed case of pure hydrogen star stock of nuclear energy is not enough for more than 100 gazillion years , plot in real time the phylogenesis of a stars breeding is an order of magnitude less than the manifestly inflated estimates . hardly tens of one million million millions of years - insignificant time for the maturation of our wandflower , whose age is not less than 10 one thousand thousand years. Age of massive stars is comparable to the age of mankind on Earth! So the star (at least , massive gamy luminosity ) can not be in the galax initially , ie from the moment of its formation . It turns out that either year in the extragalactic nebula dies at least one star . So , in order to starry folk is not degenerated , infallible to the same reasonable was form stars in our galaxy each year. In order to for a long time ( billions of years old ) Galaxy would maintain unaltered its basic features (eg , the statistical distribution of stars in classes, or that practically the same thing, by the spectral classes ) , it is necessary that it mechanically maintains a participating equalizer between born and perishing stars. In this respect, similar to the Galaxy primeval timberland of trees of different types and ages , and the age of the trees is much less than the age of the forest. there is, however, one important difference between the Galaxy and the forest . In the spirit of the galaxy of stars with a mass less than solar exceeds its age . Therefore we should yield a drowsy increase in the number of stars with a relatively small mass , as they are good-tempered not but to die, but continue to be born . But for the more massive stars, the above-named dynamic equilibrium must needfully be carried out .\n\nGas-dust complexes - the cradle of stars\n\nWhere do in our galaxy and the young sverhmolodye star? For a long time , according to established customs , dating back to Kant and Laplace hypothesis about the origin of the solar system , astronomers assumed that stars are formed from the scattered diffuse gas-dust environment . There was only one rigorous theoretical foundation for this dogma - the gravitational asymmetry of an initially same diffuse medium . The fact that in such a medium is inevitable , small perturbations density i.e. deviations from strict uniformity. in the future, howe ver, if the mass of these condensations exceed a certain limit , downstairs the influence of gravitational force small perturbations allow for produce and initially homogenous medium is humbled into several condensations . infra the influence of gloominess , these condensation lead continue to tighten and may be expected to ultimately turn into a star.\n\nThe characteristic time of the compression of the cloud to the size of the protostar can be estimated by a simple formula mechanics, which describes the free fall of a body chthonic the influence of some acceleration. So, for example , a cloud with a mass equal to the sun resulting crawl in a million years .\n\nIn the process just described, the first stage of condensation of gas-dust clouds in the star, which is called the free-fall stage discharge certain amount of gravitational energy. half(a) freed compressive clouds energy must leave the cloud in the form of infrared radiation radiation , and the other half g o to warmth of the material .\n\n at once the contracting cloud becomes opaque to its infrared luminosity it will plummet . It will continue to shrink , but not according to the law of gravity, but much slower. Temperature of its interior , after the dissociation of molecular hydrogen is over, will certainly rise, since half of the released compressive gravitational energy will go into heating the cloud. However, such an object called a cloud anymore. This is a real protostar .\n