Stars: Star and Encyclopædia Britannica Essay

Submitted By tlaxer
Words: 655
Pages: 3

The birth of a star is a very long and complex process. It take a great length of time for a nebulae, which is a cloud of gas and dust in space, to transform into a full-fledged star. The most basic process of a star’s formation is that stars develop due to the gathering of enough matter to achieve a critical mass around 80 times of what Jupiter’s mass is. At this point internal pressures increase the core temperatures high enough to spark nuclear fusion. Brown dwarfs are an example of a type of failed star. They don’t fuse hydrogen so they technically are not considered to be stars. They do not fuse due to the fact their masses are below 80 times Jupiter’s, therefore not enough pressure is created to raise internal temperatures necessary to fuse. If two of these brown dwarfs were to merge a star would be created. The first step in the birth of a star is to wait. Things like dust, gas and other materials sit around the nebulae, and wait for eons until a passing star passes through or by the nebula. Once this process happens its gravity makes swirls and ripples. This process involving the stars is called accretion, and causes the stars or clusters to grow larger. Though, if the molecules in the nebula have energy of their own, they will resist the collapse. Next, If the cloud’s mass is larger then its critical mass, it will collapse. If not the star will keep on swirling and clumping, but these clumps are not permanent. Continuing on the process of becoming a star, the clumps of matter continue to group together in the nebula until they are giant clumps of dust and gas. After this the clumps have almost reached sun-like sizes. The gas is so dense that it no longer loses heat in the surrounding nebula. Now the heat that it generates is retained, and it begins to heat up. At this stage of the process the star is known as a protostar. An interesting fact is that from the start of the collapse to the current stage which we are at right now takes around a few hundred years. Slowly as the protostar becomes larger, gravity acts on it squeezing it tighter, which makes pressure build up and heat increase. Next, in the development of stars there is a time period between when protostars develop and they reach their main stage of development, and this is called the pre-main sequence. During this point in the birth of a star, it is is still a proto, not having ignited fusion, but still is contracting. The final step in the birth of a star is when the pressure of a star’s center…