ASTRO-110 Lecture Notes - Lecture 28: Massless Particle, Helioseismology, Positron
18 Sep 2020
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Document Summary
Hydrogen burning at the center of the sun usually takes place in a three-step process. Step 1: two protons (hydrogen nuclei, or 1h, shown in red) combine to form a heavy isotope of hydrogen (2h) with one proton and one neutron. ), a neutral, nearly massless particle, as well as a positively-charged electron called a positron (e+). This positron encounters an ordinary electron (e-), annihilating both particles and converting them into gamma-ray photons ( Step 2: the nucleus of 2h from the first step combines with a third proton, forming an isotope of helium (3he) and releasing another gamma-ray photon. Step 3: two 3he nuclei formed via the first and second steps collide, forming a different helium isotope with two protons and two neutrons (4he) and releasing two protons. The gamma-ray photons released in these steps, as well as the kinetic energy (energy of motion) of the released protons, are the source of the sun"s energy.
