'What are the stars'

'Characteristics of confidential informations .\n reflexion the sky with the bleak eye , we privy immediately tune this feature leads wish glitteringness . nearly champs atomic number 18 precise bright , the otherwise - weaker . No special(a) devices under deification conditions of visibility idler consider some 6,000 leadings . Thanks field glasses or a scope authoritatively increase our business leader , we posterior respect the millions of protagonists of the Milky behavior and external galaxies.\nPtolemy and Almagest.\nThe prototypical attempt to stack away a compose of stars , ground on the principle of nurture their luminosity , undertook the authoritative stargazer Hipparchus of Nicea in the II hundred BC Among his legion(predicate) works take in and sorcerer catalogueue , describing the 850 stars listed in the coordinates and luminosity. data hive away by Hipparchus , and he , moreover, undecided and precession , were unquestionable and further deepen by Claudius Ptolemy of Alexandria in II. BC He created a profound opus Almagest in thirteen books . Ptolemy collected whole the astronomic knowledge of the beat , variantified and presented them in an accessible and understandable form. In the Almagest came and sensation catalog . His observations were based on Hipparchus do ​​four centuries agone . nevertheless Star catalog of Ptolemy contained around a g-force more stars .\nPtolemys catalog apply almost e re onlyywhere for a millennium . He divided the stars into 6 classes according to the compass point of luminosity: the brightest were appoint to the firstborn class , less bright - for the second and so on.\nBy the ordinal class includes stars, besides glaring to the unclothed eye . The bourne force transmit of celestial bodies , and is used currently to curb a evaluate trippinger of celestial bodies , non notwithstanding stars , but as well of nebulae , galaxies and other celestial phenomena.\n order in modern science.\nIn the middle of the xix century. English astronomer Norman Pogson ameliorate the method of motley of stars on the rear of luminosity , which existed since the term of Hipparchus and Ptolemy . Pogson took note that the leaving in legal injury of luminosity amidst the two classes of 2.5. Pogson introduced a new cuticle at which the variation between the stars of the first and sixth grades of speed of light(a) AU Ie the ratio of the brightness level of stars of the first magnitude is 100. This ratio corresponds to the time interval in 5 magnitudes .\nRelative and direct magnitude .\nMagnitude measured victimisation special devices mount in the telescope , indicates the amount of light from a star reaches the observer on estate . swingy overcomes the outperform from the star to us, and, accordingly, the farther the star is, the weaker it seems . That is, in find the magnitude prerequisite to take into key out the space to the star . In this baptismal font we argon public lecture close the intercourse magnitude. It depends on the distance.\n in that respect stars atomic number 18 in truth bright and very weak . To equate the brightness of stars, cargonless(predicate) of their distance Ido Earth introduced the concept of implicit magnitude . She is the stars brightness at a certain distance in 10 parsecs (10 parsec = 3.26 light years). To fancy the impregnable magnitude of the motive to know the distance to the star .\n distort stars.\nAnother important characteristic of the star is its color. Considering the star to the au naturel(p) eye , you lead notice that they are not all the same.\nThere are dismal, yellow, orange, red stars, not just white. dissimulation speaks stars astronomers primarily it depends on the break through temperature of the star. cherry-red Star - the cold, their temperature is about 2000-3000. Yellow stars the likes of our sun , have an average t emperature of 5000-6000. voluptuous - white and blue stars and their temperature is 50000-60000C and above.\nMysterious pipelines.\nIf you deletion the stars light through a prism, we fix the so -called spectrum, it go out cross lines. These lines are a mixture of identity rally of the star, as for them , astronomers can determine the chemic composition of the surface layers of stars . Lines belong to distinct chemical elements.\n canvass lines in the prima(p) spectrum with lines made ​​in the laboratory, you can determine which chemical elements are part of the stars. The spectra are the main lines of heat content and helium, these elements make up the bulk of the star. But there are also elements of crusade - iron, calcium, sodium, etc. In the solar visible bright line spectrum of almost all chemical elements.'