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Birth of a Nebula
A nebula is born in two primary ways -- moments after the creation of the universe itself and after a supernova. After the birth of the universe atoms were created and congregated in large dust clouds. This means a nebula made of these dust particles contains no stellar or planetary matter; instead it's made up of original matter from the beginning of the universe. A supernova occurs at the end of a star's life cycle when the star explodes. The matter ejected from the star creates massive dust and particle clouds made up of a mixture of primordial and new materials from previous stars.
Types of Nebula
The five types of nebulae are the emission nebula, reflection nebula, dark nebula, planetary nebula and supernova remnants. An emission nebula is a large cloud high temperature gas, mostly hydrogen. The hydrogen atoms are energized by ultraviolet light from nearby stars and emit synchrotron radiation, as well as red light, as they fall down to a lower energy level. The reflection nebula contain dust that reflects the light from a nearby stars. A dark nebula is very similar in composition to a reflection nebula, but instead of reflecting light it blocks the light emitting from the stars behind it. The planetary nebula actually has nothing to do with planets; it manifests when stars enter the red dwarf stage and shed their outer layer of gas into space. Supernova remnants are caused by a violent explosion of a star at the end of its life.
Synchroton Radiation
Synchrotron radiation refers to a type of radiation that occurs when particles are accelerated in an orbit around a large celestial object in a curved path. This happens when relativistic and ultrarelativistic electrons gyrate in a magnetic field which accelerates them on a curved path. Furthermore, synchrotron radiation is nonthermal, a term that describes the emission of high-energy particles. The particles gyrate in spiral moving from high to low-energy frequencies. If the gyrating particles remain constant it means that there is an energy source feeding the process, and radiation isn't emitted. Gas and dust particles of nebulae make this energy shift because of large celestial bodies, such as suns and planets, that emit massive magnetic fields found within nebulae.
The Crab Nebula
The Crab Nebula is an excellent source of synchrotron radiation. The nebula is a remnant of a supernova which was observed by the Chinese and Arab astronomers in 1054 A.D. The nebula has been a rich source of information and provides an excellent example of synchrotron radiation. The characteristic red light emitted by the Crab Nebula is a visible testament of gyrating hydrogen atoms moving from high to low energy frequencies along a magnetic curve and emitting synchrotron radiation.
Other Types of Radiation Found In Nebulae
Although nebulae themselves are only capable of emitting synchrotron radiation, plenty of other forms of radiation called electromagnetic radiation are emitted from celestial bodies found within nebulae. Suns are the primary source of radiation in the universe because they heat the gases to extreme temperatures that infusion and split atoms. Suns produce ultraviolet, infrared, x-rays and gamma rays, all of which are highly irradiated. Of these, gamma rays are the most harmful and happen when atoms are accelerated to extreme speeds by heat. Electromagnetic radiation is best described as a stream of photons that moves at the speed of light. The wave length and frequency of this stream of photons is what distinguishes one type of electromagnetic radiation from another.