Stellar Evolution and Hydrostatic Equilibrium

Stellar Evolution and Hydrostatic Equilibrium in the Study of Stars in the Field of Astronomy

Science of Stars

In studying the science of stars in the field of astronomy, it is vital to determine its physical properties and chemical composition in order to have an understanding of how equilibrium takes place and is a vital process that stars undergo. Stars are generally known as spheres containing hot gases and emit light and electromagnetic radiation.

The chemical components of stars mainly include the presence of incandescent gases, specifically hydrogen and helium. Stars' physical properties include mass, size, luminosity, temperature, and energy output. Combining both the chemical components and physical properties of stars make up the stellar structure, a fact generated from the theory of stellar structure.

In the theory of stellar structure, it was posited that the mass and chemical components of a star ultimately determines a star's other characteristics. This theory was especially applicable to stars with different masses, since all of the stars have no difference in chemical composition (i.e., hydrogen and helium). A star that has greater mass would have greater and increased luminosity as compared to a star with lesser mass.

Over time, however, as stars consume the hydrogen contained within them, the process of equilibrium takes place. The death of a star occurs when the hydrogen is consumed, and it no longer has capability to induce nuclear reactions as a result of this loss of hydrogen component. Its death, however, is compensated and buffered by the birth of another star from that same (dead) star.

A dead star or black dwarf would be converted to interstellar matter spread out in space, and would eventually form a new star. This equilibrium process is made possible through thermonuclear reactions, wherein remaining hydrogen atoms are formed together to create a helium nucleus. Thus, through this process of death and eventual birth of a new star through stellar evolution, equilibrium was conducted and achieved.

Another equilibrium process that stars undergo is through the concept of hydrostatic equilibrium. Hydrostatic equilibrium looks into the relationship of the star's thermal pressure and its weight (mass plus the force of the gravity). This process is characterized as the balance between thermal pressure, which is directed outward, and the weight of the material above pressing downward -- that is, directed inwardly.