What does "Ionisation" mean?
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Ionisation is the process where an atom or molecule gains or loses an electric charge. This happens when the energy supplied to it is enough to remove electrons, which are the negative particles in an atom. When this occurs, the atom becomes positively charged, while the free electron is negatively charged.
Importance of Ionisation in Space
In space, ionisation plays a key role in shaping the environment of galaxies. It occurs in areas with high energy, often where new stars are being born. The light and energy from these stars can cause the surrounding gas to ionise, which means the gas becomes a mix of charged particles.
Types of Ionised Gas
There are different types of ionised gas found in galaxies:
HII Regions: These are areas filled with ionised hydrogen, often found around young, hot stars. They act as a sign of new star formation.
Diffuse Ionised Gas (DIG): This is a more spread-out form of ionised gas that exists in the space between stars. It is less dense than HII regions and has its own unique properties.
Factors Influencing Ionisation
Several factors can affect how ionisation happens in galaxies:
Star Age: Different ages of stars emit different types of energy. Young stars provide a lot of energy, creating a strong ionisation effect, while older stars become less effective over time.
Cosmic Rays: These are high-energy particles traveling through space. They can also contribute to ionisation in areas like the Galactic Centre, helping to explain the high ionisation rates in those regions.
Shocks in Space: When stars explode or form, they can create shock waves that also contribute to the ionisation processes in the surrounding gas.
In summary, ionisation is a vital process that helps scientists understand how stars interact with their environment and contribute to the overall structure of galaxies.