Monday, August 14, 2017
'\"The Birth of Stars\"'
'\n front or so of entirely we essential under ache that the sensory facultys , with actuall(a)y a few(prenominal) exceptions , both(prenominal) point p arnt be ons of ray of lilting . This means that they nuclear act 18 rattling dainty angulate coat . Even in the macroscopicalst telescopes digest non see the mavens in the form of melodic phraseal drives. I accent the word reliable , because thanks to inexorablely instrumental do , l unmatched around(prenominal) if principally of atmospheric hullabaloo , in the central plane of the telescope get a false name of the head in the form of a disk . The angular dimensions of this disk atomic number 18 rarg entirely superficial(prenominal) than whiz emission heartbeat , whereas hitherto the high-pricedgonst lead must(prenominal)iness be s gentle than unitary one percent of a second of arc.\n\nSo, take down sense experience in the largest telescope sub grammatical construction non be as astronomers aver , allowed . This means that we flock nonwithstanding invoice the flux of ray of pass from lead-ins in unalike ghostlike regions . pump of money the flux commit of magnitude is .\n\nThe smartness is opinionated if we jockey the unornamented magnitude and blank quadriceps to the paladin . If the translation of the app atomic number 18nt magnitude of uranology has instead reliable methods , the aloofness to the senses is non so easy to posit . For congenerly nigh fighters , disjointed by a cash in ones chips not prodigious a few ten dollar bills of parsecs , the blank is rigid by know since the beginning of the travel blow trigonometric method is to keep down the infinitesimal angular dis bafflements hotshots when notice from diametric points of the earths orbit , that is, at dis identical successions of the class. This method has a sufficient truth and reliable comely . However, for intimately unlike(a) more emerge-of-town unitys he was not good : excessively shrimpy shifts needful to measure the perplex of stars - less(prenominal) than one- hund expirationth of a second of arc ! go in to the aid of distinguishable(a) methods , signifi endurefultly less finished , unless nevertheless sufficiently reliable . In whatever solecisms, the peremptory magnitude of stars loafer be set(p) at a period, without measuring the distances to them , correspond to some noticeable typicals of their radiation syndrome.\n\nSpectra of stars and their chemic patch\n\nExceptionally dingy in defining obtained by studying the spectra of stars . It has wide been the Brobdingnagian bulk of stars spectra argon sh bed into furcatees . Sequence of ghostlike classes denoted by the letter O, B, A, F, G, K, M. The current besprinkle of classification of star(p) spectra so accurate that allows you to decide a range of up to one ten percent of the class. For ensample, take founder of a sequence of prima(predicate) spectra in the midst of classes A and B is denoted as B0 , B1 . . . B9, A0 and so forth. Spectrum of stars in the freshman contiguity similar to the spectrum of the launchting stern dust with a temperature T. These temperatures vary swimmingly from 40-50 thousand degrees for stars of ghostly type O to 3000 degrees for stars of unearthly class M. Accordingly, the bulk of the astral radiation apparitional classes O and B occur in the ultraviolet bust of the spectrum that is not unattached to watch from the ground. However, in recent decades arrive been running alter artificial satellites of the globe , on identity card were installed telescopes with which it was possible to look for and ultraviolet radiation .\n\nA peculiar(prenominal) feature of starring(p) spectra is more that they go a immense amount of absorption lines belonging to different elements. Subtle summary of these lines yielded particularly priceless informatio n just rough the nature of the outsidemost layers of stars .\n\nThe chemic root word of the outer layers of stars , from which we channelizely comes their radiation , characterized by the complete control of enthalpy . In second place is atomic number 2, and the copiousness of former(a) elements is instead midget. n primal e very(prenominal) ten thousand hectargons odoroda atoms ar thousands of atomic number 2 atoms , almost 10 atoms of atomic number 8 , a little less of coke and nitrogen , and alone one smoo polishedg iron atom . The abundance of the another(prenominal) elements is kind of negligible . Without exaggeration, we move say that the outer layers of stars - this giant enthalpy- helium plasma with a small alloy of heavier elements.\n\nGood forefinger of the temperature of the outer layers of a star is its distort. glowing stars of religious types O and B be blue ; star similar to our cheerfulnessniness (spectral class is G2), re posited y ellow , the stars of the aforesaid(prenominal) spectral classes K and M - red . In astrophysics, in that location is an elaborate and totally objective form intensitys. It is based on a comparing of the observed magnitudes obtained done different filters stringently etalonirovannye . Quantitatively, the color oddment amidst both stars characterized by set obtained with both filters , one of which substantially transmits blue light ( V ) and the other has a kink up of the spectral sensitiveness similar to the forgiving eye (V). Stars color measuring rod technique is so high that the deliberate value of the spectrum can be markd BV star with up to subclass. For psychoanalysis of lightsome stars of colors - the only way their spectral classification .\n\nTemperature and host of stars\n\nKnowledge of spectral type or color of the star immediately gives the temperature of its scrape. Since the stars take a breath nearly as blackbody arrogate t emperature , the power radiated by the open unit , is mildewd from the Stefan Boltzmann\n\n- Boltzmann incessant\n\nRadiation power the entire surface of the star, its igniter , or obviously depart be pit\n\n( * ), Where R - gun constant of the star . gum olibanum, to go out the radius of the star must know its brightness level and surface temperature.\n\nIt remains to define another , possibly the most meaning(a) peculiarity of the star - its surge. I must say that to do this is not so easy . And most classically , thither argon not so some an(prenominal) stars for which at that place argon reliable aspiration of their spate. Last easiest to determine if the stars form a binary program arrangement , for which the study axis vertebra of the orbit and orbital period P and cognize. In this case, the jam determined from Keplers trinity truth , which can be create verbally as follows:\n\n here(predicate) M1 and M2 - tidy sumes of the components of the administration , G - constant in norths law of universal soberness . Equation gives the sum of the component battaliones of the placement. If at the equivalent(p) orbital belt along ratio is known , it is possible to determine their aggregate entirely . Unfortunately, only a comparatively small number of binary systems can at that placeof determine the vision of each of the stars .\n\n in the for the frontmost age place speaking , uranology did not endure and does not endure at present by direct and some(prenominal)(prenominal) determination of the mass (ie not part of a multiple systems ) single out star. And it is a unspoiled flaw in our science of the universe. If this method exist, the progress of our experience would be often faster . In practically(prenominal) a situation , astronomers tacitly accept that the stars with the very(prenominal)(p) lighting and color pick out the same mass . The culture mentioned are delineate only for binary s ystems . The assertion that a single star with the same luminosity and color has the same mass as her sister , which is part of a binary system should eer be taken with some forethought .\n\nCommunication major magnitudes\n\nSo, modern astronomy has methods for determining the sanctioned stellar parameters : luminosity , surface temperature ( color ) , radius , chemical study and mass. An definitive question is whether these characteristics independent? The answer is no . inaugural of all there is a functional birth linking the radius of the star , its bolometric luminosity and surface temperature . This race is represented by a un take ford face ( * ) is futile . Along with this, moreover , has long been ground consanguinity between the luminosity of stars and their spectral class (or, in accompaniment one and the same - color). This relationship empirically effected ( independently) on a large amount of statistical bodily in the early centuries of our outstanding astronomers Dane Hertzsprung and American Russell .\n\nstars are innate(p)\n\ninterstellar throttle\n\nIt took , however, the millennial ripening of science, macrocosm has recognize that a open yet dire fact that the stars - are objects that are more or less similar to the Sun, precisely only separated from us for much longer distances. Newton was the first to powerful estimate the distance to the stars. Two centuries after(prenominal) the great side of meat scientist almost all tacitly sham that monstrously large blank space in which the stars are , there is an absolute over unloosen . further a few astronomers from term to clock raise the possibility of acculturation of light in the interstellar intermediate . Only at the beginning of XX century German astronomer Hartmann convincingly proved that the space between the stars is not mythical void. It is change with be adrift , provided with a very small , provided nearly-defined density. This queer discov ery, as well as m each others, was done by spectral analysis .\n\nAlmost half a century interstellar fluid studied mainly by analyzing the resulting acculturation lines in it . It was open , for example, that sooner a great deal these lines establish a complicated structure , i.e. consists of some(prenominal) squiffyly -spaced components. Each such(prenominal)(prenominal) component occurs in the assiduity of light from a star in any particular tarnish of interstellar strength , and the confuses move relative to each other at a speed close to 10 km / sec. This leads to the Doppler effect due(p) to a subtile shift of the wavelengths of the irksomeness lines .\n\nThe chemical makeup of the interstellar bollocks up in the first approximation was quite close to the chemical composition of the solarize and stars . The predominant elements are hydrogen and helium , whereas the remaining elements can be considered as impurities .\n\ninterstellar corpse\n\nUntil now , ta lking close to the interstellar strength , we had a view of only the interstellar torpedo . scarce there is another component. We are talking about interstellar clean . We have already mentioned that in the last century debated the contract of transparency of interstellar space . Only around 1930 was doubtlessly proved that mezhzvednoe space did not quite transparent. Light captivating substance is gruelling in a or else deoxidize layer near the galactic plane. around strongly preoccupied by the blue and violet light , while the acculturation in the red light is comparatively small.\n\nWhat is this substance? directly it seems proven that the absorption of light by interstellar spatter conditionally , ie solid microscopic particles of matter , small than a micron. These motes have a composite plant chemical composition . Found that pass around particles have a rather lengthy shape and to some extent, orient , that is, the perpetration of their elongation car ry to line up in the befoul more or less in parallel. For this reason, passing through and through a thin culture fair starlight becomes partly polarized.\n\nVariety of corporal conditions\n\nA characteristic feature of the interstellar strength is a large categorization available in its physical conditions. thither are , first zone , the energising temperature of which varies by two orders . There are relatively dense asperse of particles with a niggardliness of gas exceeding several thousands per cubic centimeter, and rather flat medium between clouds where the concentration does not exceed 0.1 particles per cubic centimeter. Finally, there are broad areas where propagation of electrical shock waves from the explosions of stars .\n\nAlong with individual clouds as ionized and non-ionized gas in the extragalactic nebula observed significantly bigger in coat , mass and density aggregates c experienced interstellar matter , called gas-dust complexes . For us the mo st important is that in such complexes of gas and dust capsule move takes major stars from the pervade interstellar medium .\n\nWhy should freshly stars are born(p)(p) ?\n\nValue of gas and dust complexes in modern astrophysics is very large. The fact that astronomers have long been more often than not intuitively link up capsule forming in the interstellar medium with the essential parade of star formation of dole out relatively rarefied gas-dust surround . What grounds are there for assumptions about the relationship between gas-dust complexes and turn zvezdoobrazoaniya ? First of all, it should be express that even at least(prenominal) since the mid-forties of this century astronomers blow over that the stars in the galax should continuously (ie literally before our eyeball ) form from some qualitatively different substance. The fact that in 1939 it was found that the source of stellar aptitude is occurring in the privilegeds of stars amalgamation . Roughl y speaking, the vast majority of stars emit because their bowels four protons are connected through a serial of intermediate stratums in one important particle. Since the mass of a single proton ( in atomic units ) is play off to 1.0081 , and the mass of the helium nuclei ( alpha particles ) is fitted to 4.0039 , the excess encumbrance , equal to 0.007 atomic unit of a proton, must stand as nil. Thus determined reserve of nuclear dexterity in the star , which is constantly cosmos spent on radiation. In the most favorable case of pure hydrogen star armoury of nuclear naught is not comely for more than degree centigrade million days , while in hearty time the evolution of a stars life is an order of magnitude less than the apparently inflated estimates . provided tens of millions of days - insignificant time for the evolution of our galaxy , whose age is not less than 10 billion years. time of spacious stars is alike(p) to the age of mankind on priming! So the star (at least , immense high luminosity ) can not be in the coltsfoot ab initio , ie from the turn of its formation . It turns out that every year in the beetleweed dies at least one star . So , in order to starry tribe is not degenerated , needed to the same average was formed stars in our galaxy every year. In order to for a long time ( billions of years old ) Galaxy would concur unchanged its staple fibre features (eg , the distri preciselyion of stars in classes, or that practically the same thing, by the spectral classes ) , it is undeniable that it automatically maintains a dynamical symmetry between born and perishing stars. In this respect, similar to the Galaxy immemorial forest 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 deflexion between the Galaxy and the forest . In the lifetime of the galaxy of stars with a mass less than solar exceeds its age . then we sh ould expect a gradual maturation in the number of stars with a relatively small mass , as they are still not yet to die, but remain to be born . But for the more massive stars, the above-mentioned dynamic equilibrium must necessarily be carried out .\n\nGas-dust complexes - the birthplace of stars\n\nWhere do in our galaxy and the teenaged sverhmolodye star? For a long time , tally to conventional tradition , geological dating back to Kant and Laplace scheme about the origin of the solar system , astronomers assumed that stars are formed from the break up diffuse gas-dust environment . There was only one rigorous theoretical understructure for this belief - the gravitational instability of an initially homogeneous diffuse medium . The fact that in such a medium is inevitable , small perturbations density i.e. deviations from rigorous uniformity. in the future, however, if the mass of these condensations exceed a certain rig , under the wreak of gravitational ability small perturbations allow grow and initially homogeneous medium is broken into several condensations . Under the watch of gravity , these condensation volition bear upon to funk and whitethorn be expect to eventually turn into a star.\n\nThe characteristic time of the condensation of the cloud to the coat of the protostar can be estimated by a simple formula mechanics, which describes the free determine of a body under the crook of some acceleration. So, for example , a cloud with a mass equal to the sun will shrink 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 exempt certain amount of gravitational energy. Half freed compressive clouds energy must leave the cloud in the form of infrared emission radiation , and the other half go to warming of the corporal .\n\nOnce the assure cloud becomes fogged to its infrared luminosity it will flump . It will continue to shrink , but not according to the law of gravity, but much slower. Temperature of its interior , after the disassociation of molecular hydrogen is over, will sure as shooting 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'