Neon-burning process

As Neonbrennen are a group of nuclear fusion reactions inside massive stars with an initial mass of at least eight solar masses, in which the conversion of the starting material neon energy is released. This requires high temperatures of at least 1.2 x 109 Kelvin and high density of at least 4109 kg / m³.

At such high temperatures, the photo- disintegration plays an important role. Here, some of the former by fusion processes (see carbon burning) produced neon nuclei 20Ne are γ by high-energy gamma quanta split 4He ( α - particles ) in 16O oxygen and helium:

The 4He can react with another 20Ne to produce magnesium 24Mg:

In an alternative reaction pathway initially takes place at the Neutronenanlagerung 20Ne, which is then reacted with an α - particle and a neutron emission is also n 24Mg:

The neutron produced in the second step can be received in a re- run of the reaction.

The Neonbrennen begins when the carbon is used up in the core of the star by the foregoing carbon burning, and an oxygen -neon magnesium core is formed. The fusion processes grind to a halt, after which the radiation pressure in the core is no longer sufficient to counteract its own gravity. Therefore, he is so far compressed until the created by temperature and pressure increase caused eventually the conditions for the Neonbrennen.

During the Neonbrennens the core with oxygen and magnesium enriched, and neon is reduced. After a few years ( in the article Star there is an exemplary time scale for the duration of the individual combustion phases) the star has consumed all of its neon, and the core cools down again now and is compressed by gravity. Temperature and pressure rise again, until the onset of the oxygen burning.

Credentials

Hydrogen burning helium burning · · · carbon burning Neonbrennen · · oxygen burning silicon burning

• Astrophysical process