Page 09

Star Movies Page 09

A star begins as a collapsing cloud of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Once the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process. 

The remainder of the star's interior carries energy away from the core through a combination of radioactive and convective processes. The star's internal pressure prevents it from collapsing further under its own gravity. Once the hydrogen fuel at the core is exhausted, a star with at least 0.4 times the mass of the Sun expands to become a red giant, in some cases fusing heavier elements at the core or in shells around the core. 

The star then evolves into a degenerate form, recycling a portion of its matter into the interstellar environment, where it will form a new generation of stars with a higher proportion of heavy elements. Meanwhile, the core becomes a stellar remnant a white dwarf, aneutron star, or (if it is sufficiently massive) a black hole.

Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. 

When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a cluster or a galaxy.