Stars are the beautiful objects seen in the sky but what makes them beautiful? What are they made up of?
Stars emerge from the dust clouds that are present in all galaxies. The great disturbance and movement deep within the dust cloud causes the knots of a particular mass by which gas and dust particles present in the clouds strike with each other having their own gravitational attraction. With the collapsing of dust particles and gas the knots present in the center begins to heat up. These are called as protostar which gradually changes to star because of regular collision of gases and dust particles. Sometimes these gases and dust particles collapse in such a way that they form two or sometimes three blobs which make some stars to appear in a group. Most of the stars in the Milky Way galaxies are multiple stars. It is not necessary that whole of the cloud changes to star but the left dust can become planets, comets, asteroids or they remain as it is.
U.S astronomers say that the stars are formed in one of the two ways. One is top-down process. This is a process in which molecular bodies break into gaseous form which further collapses and forms a small seed like body and the surrounding gas and dust particles settles on these bodies which further becomes a big star but according to Mark Kreimholz of Princeton university, Christopher Mckee of California university and Richard Klein of National laboratory believes that this theory of bottom-up is wrong because a small body like seed cannot grow to a big star within the life time of a cloud.
After the star is formed the internal core having central force of gravity attracts the surrounding materials by which it may happen that star can become supernova, and explodes violently forming even heavier elements. But sometimes in the other cases explosion does not happen and only the interior raise to the surface and then leaves in the space with the blowing off the outer layer.