STARS

Stars are actually highly compressed,extremely hot gaseous bodies,capable of emitting electromagnetic radiation.Stars are self luminous.They are composed mostly of hydrogen,and to a smaller extent,helium.Carbon,sulphur etc are also present in very small amounts.

         Ther are 8000 stars visible to the naked eye,as seen from the earth.But actually there are approximately one hundred thousand million stars in our Milky Way galaxy alone!.The vast majority are so far away that they are not visible.Our sun is just one of the stars in our galaxy.The star nearest to us is Proxima Centauri,which is one of the three stars in the triple star group called Alpha Centauri.

RED GIANTS

          These are very large stars.Red giants are formed as one possible end product of the evolution of stars.These are diffused systems having very small densities.

WHITE DWARFS

These are the end products of another variation of stellar evolution.Here,stars shrink and attains a very high density and temperature.The star called Companion of Sirius is an example of a white dwarf.The dia meters of white dwarfs are of the order of only 1000 to 2000 kilometres.

NEUTRON STARS

          These are smaller than white dwarfs and arethe end products ofanother evolutionary route.They have diameters of the order of 10m to20km only!Densities are around 600 tonnes /cubic centi metre.

BLACK HOLES

          This is also an end product of stellar evolution!The star shrinks finally to almost a point,with density approaching infinity!The gravitational pull is so great that not even electromagnetic radiation can leave the system.As a result of this enormous gravitational pull and absence of radiation,the system appears black.

CHANDRASEKHAR LIMIT

           The great Indian-American astrophysicist has made great contributions to the study of stars.He discovered what is now known as the “Chandrasekhar limit”.If the ratio of the mass of the star to that of the sun is less than 1.44,but below 3.6,the star would become a neutron star.And if the ratio is more than 3.6,the  en dresult is a black hole.