Stars are born in giant stellar nurseries of gas and dust called molecular clouds. The gas that forms these vast clouds is much thinner than the atmosphere on Earth, yet there is just enough gravity to force clumps of gas and dust to contract into a ball. This is the beginning of a star. It will continue to grow until it is large enough for nuclear reactions to begin in its core. A molecular cloud remains dark until the light from new stars illuminates the surrounding gas, turning it into a nebula.
Nebulas are either remnants of matter from the original big bang or the result of stars either collapsing or going supernova. Nebulas have long been noted and observed by astronomers but very little was known about them until the 21st century. Galaxies because of their similar appearance were once thought of as nebulas. It was later determined that they were actually larger grouping of stars a great distance away from the Earth. So how are Nebulas star forming regions? The answers lie in the gravitational force and nuclear fusion.
Most nebulas are disparate clouds of gas and cosmic dust floating in the interstellar medium. Nebulas are the more dense parts of the gas and dust that exist in the space between stars and galaxies. We know due to the law of universal gravitation that every particle in the universe exerts an attractive force on every other particle. This happens over times with nebulas as the particles that make up the interstellar medium start to gather together.
Since gases have mass it is inevitable that the process will continue as great mass will create a stronger gravitational field. At some undefined point in time a tipping point between the gas pressure and the gravity of the nebula is crossed and the nebula collapses under its own gravity. Since molecular hydrogen is the most abundant element in the nebula the pressure from the collapse causes the nebula to undergo nuclear fusion. This starts the birth of a star.
As evidenced by how many stars and galaxies are in the universe you can see that is process that happens just about everywhere. More recently scientists have started become interested in how common it is for stars to from planets, especially those that are likely to support life. Scientists have recently discovered one such planet Gliese 581-g. This planet while closer to it star than Earth is well within habitable zone necessary for liquid water and the right temperatures for life to occur.
The study of nebulas and the interstellar medium have yielded a lot important information about the formation and stars. As better telescopes and probes are created we will get a clearer picture about our universe and how it was formed and continues to grow over time.
Picture Credit : Google
