Credit & Copyright: Matthew Spinelli
One of the most recognizable objects in the sky, the Orion constellation contains the Orion Nebula among several other known nebulas which are in the process of forming stars. The Orion Nebula is visible to the eye in pinkish light, emitted just bellow the three diagonal stars.
Introduction
The purpose of this project is to learn something new and exciting in our complicated universe and then show how it is related to physical concepts. I hope that in clicking through the several pages on this site you will also learn something new or interesting about the subject, and then you may even go and explore on your own.
The formation of stars and planets is one of the most fundamental problems in astrophysics and the reasons are obvious as one thinks about the origins of our universe. In studying the formation of other solar systems, scientists are finding more information about our own solar system and the wonders if life exists on other planets.
The process of star formation basically takes place as a war between entropy and gravity. Entropy and gravity are discussed in most general physics books. Entropy is defined as a measure of disorder in an isolated system. Stars are born within molecular clouds, which can define an isolated system. In a molecular cloud, "entropy" manifests itself as pressure forces and turbulence. Within this process gravitational forces tend to pull things together, whereas entropy tends to spread things out. The issues involved between entropy and gravity are the basic physical concepts in the star formation process.
Definitions
Molecular Clouds are large massive aggregations of molecular gas that are much denser and colder than the surrounding interstellar gas (space).
Cores of molecular clouds are where the stars actually form; they are regions of small subcondensations within the much larger molecular clouds.
Ambipolar Diffusion is a process through which the cores develop; this process supports the core against self gravity as the magnetic field slowly diffuses outward contributing to the pressure support.
Collapse occurs after the core enters an unstable equilibrium state as the thermal pressure alone supports the core against self gravity (at least in the central regions).
Circumstellar Disk forms around the forming star after the core's collapse due to the rotating cloud cores which contain large amount of angular momentum (i.e., spin).
Protostellar Phase of evolution indicates a protostar surrounded by disk and the infalling gas and dust.
Bipolar Outflow phase occurs when the incoming material slowly decreases outward in a narrow angular extent from the rotational poles of the protostar.
The outflow of the material eventually separates the star/disk system from the core that it was made of and the object becomes a young star.