Subatomic Particles

Even though astrophysicists looks at the largest objects in the universe, you can't understand how they work unless you also understand the smallest objects in the universe. These are particles that are even smaller than a single atom, and are thus called Subatomic Particles. Atoms, as you may know, are made up of a nucleus surrounded by orbiting electrons. The nucleus of an atom is made up of protons and neutrons. Besides these, there are many other subatomic particles that we need to know about in order to understand the internal workings of a star.


ProtonProtons are one of the fundamental building blocks that make up atoms. In fact, the simplest atom, a hydrogen atom, is just one proton orbited by a single electron. In stars, most of the hydrogen has been ionized (losing its electron), which means that when we're talking about hydrogen inside of stars, we're usually just talking about protons.

Protons are fairly large and heavy for subatomic particles, and they carry a positive charge.


ProtonNeutrons are very similar to protons, in that they are found in the nucleus of an atom, and they are fairly large. Unlike protons, however, a neutron has no charge. Neutrons are important in the creation of atoms because they help stabilize the nucleus. An atom that has too many or too few neutrons generally won't last very long, and will simply break apart into smaller atoms that are more stable.


ProtonElectrons are negatively charged particles that generally orbit the nucleus of an atom. Electrons are much smaller than protons or neutrons. Despite being so small, their charge is as strong as a proton, which means that one proton and one electron will balance each other out.

Even though electrons don't normally exist in the nucleus of an atom, the nucleus of an atom will occasionally give off an electron in a process known as Beta Decay. When this happens a neutron turns into a proton and an electron is released in order to balance out the charges. The opposite can also occur, where the nucleus of an atom can absorb an electron, changing a proton into a neutron. This is known as Electron Capture.


ProtonPositrons are particles of antimatter. They are the antimatter equivalent to an electron, which means that they are small, positively charged particles. Positrons are created during the process of hydrogen fusion, where they carry away the positive charge from protons so that they can become neutrons. However, since positrons are antimatter, they don't usually make it very far. As soon as one comes into contact with an electron (which most atoms have a lot of), the two particles annihilate each other, releasing Gamma Rays.


ProtonNeutrinos are very small, neutrally charged particles. They are even less massive than electrons and positrons. Because they are so small and they don't interact with electromagnetic fields, neutrinos usually pass straight through solid matter, making them very hard to detect. They carry energy away from reactions in the form of their own kinetic energy. Since it's very unlikely for these tiny particles to interact with any others on their way out of the star, the generally carry their energy away into space.

The only time neutrinos really react much with other particles is during huge neutrino bursts, like the kind that occur during a supernova. During a supernova, there are so many neutrinos released that they crash into other particles, transferring huge amounts of energy and starting off new fusion reactions.

Gamma Rays

ProtonGamma Rays are photons, or particles of light, with extremely high energy. Gamma Rays have no mass, but they can carry huge amounts of energy and can still interact with other particles. That makes gamma rays one of the most dangerous kind s of radiation for humans.


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