Page 08

Star Movies Page 08

For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. 

Almost all naturally occurring elements heavier than helium are created by stars, either via stellar nucleon synthesis during their lifetimes or by supernova nucleon synthesis when very massive stars explode. Near the end of its life, a star can also contain a proportion of degenerate matter. 

Astronomers can determine the mass, age, chemical composition and many other properties of a star by observing its spectrum, luminosity and motion through space. The total mass of a star is the principal determinant in its evolution and eventual fate. 

Other characteristics of a star are determined by its evolutionary history, including diameter, rotation, movement and temperature. A plot of the temperature of many stars against their luminosities, known as a Hertz sprung–Russell diagram (H–R diagram), allows the age and evolutionary state of a star to be determined.