Stellar evolution is the study of how a star changes throughout its “lifetime”. The major changes which a star in evolution goes through are classified as: * Birth of the star, it’s the first phase of a star’s life. A “new-born” star can be a * Average star
* Massive star
* Maturity of the star, it’s the second phase of a star’s life. A “mature” star can be a * Red Giant
* Red Supergiant
* Stellar Remnants, it’s the third phase of a star’s life, just before its death. An “elder” star can be a * Planetary Nebula
A star’s life begins with a Stellar Nebula and then it can either become an Average Star or a Massive Star. If it becomes an Average Star, the next phase will be a Red Giant, followed by a Planetary Nebula and ending on a White Dwarf. If it becomes a Massive Star, the next phase will be a Red Supergiant, followed by a Supernova that can develop in either a Neutron Star or a Black Hole.
Now we will begin to go discuss more concretely every kind of star regarding its age.
A Stellar Nebula is an interstellar cloud formed by gravitational force that pulled gases together. Stars usually get formed in their centers. The ultraviolet radiation between the gases makes them visible and luminescent. Stellar nebulas are made of: * Hydrogen
An Average Star is a luminous sphere of plasma that is held together by gravity. Average stars shine due to thermonuclear fusion between hydrogen and helium in their core. An average star’s characteristics are: * 1.98 x 1030 Kg of mass aprox. (4.37 x 1030 pounds)
* 1.412 x 1019 Km3 of volume aprox. (3.11 x 1029 gallons) * 4-5 billion years of age.
A Red Giant is a star on a late phase of stellar evolution. When the hydrogen in the core of an average star is exhausted, the hydrogen in the outer shell begins to ignite due to thermonuclear fusion, causing the star to...