Ch. 14.2 Nuclear Fusion in the Sun
Ch. 14.2 Nuclear Fusion in the Sun -Nuclear fission splits a nucleus into smaller nuclei, while nuclear fusion combines smaller nuclei into a larger nucleus. -Nuclear fusion occurs in core, where energy from process makes it’s way to photosphere, the outer layer of the sun. -In the Sun, four hydrogen nuclei (protons) fuse into one helium-4 nucleus by way of the proton-proton chain. Gamma rays and subatomic particles known as neutrinos and positrons carry off the energy released in the reaction. Steps: 1.Two protons fuse to make a deuterium nucleus (1 proton and 1 neutron). This step occurs twice in the overall reaction. 2. The deuterium nucleus and a proton fuse to make a nucleus of helium-3 (2 protons, 1 neutron). This step also occurs twice. 3. Two helium-3 nuclei fuse to form helium-4 (2 protons, 2 neutrons), releasing two excess protons in the process.
-Radiative diffusion: the slow outward migration of photons -Gravitational equilibrium regulates the Sun’s core temperature: A rise in core temperature triggers a chain of events that causes the core to expand, lowering its temperature to the original value. A decrease in core temperature triggers the opposite chain of events, also restoring the original core temperature. -Energy moves through the deepest layers of the Sun—the core and the radiation zone—in the form of randomly bouncing photons: energy of each photon gets lower on the way. After energy emerges from the radiation zone, convection carries it the rest of the way to the photosphere, where it is radiated into space as sunlight (peaking in visible) Practice Questions: Which of these groups of particles has the greatest mass? Four individual protons Scientists estimate the central temperature of the Sun using mathematical models of the Sun. Solar energy leaves the core of the Sun in the form of photons. How does the number of neutrinos passing through your body at night compare with the number passing through your body during the day? About the same. Outward pressure and gravity are balanced in gravitational equilibrium.
-Radiative diffusion: the slow outward migration of photons -Gravitational equilibrium regulates the Sun’s core temperature: A rise in core temperature triggers a chain of events that causes the core to expand, lowering its temperature to the original value. A decrease in core temperature triggers the opposite chain of events, also restoring the original core temperature. -Energy moves through the deepest layers of the Sun—the core and the radiation zone—in the form of randomly bouncing photons: energy of each photon gets lower on the way. After energy emerges from the radiation zone, convection carries it the rest of the way to the photosphere, where it is radiated into space as sunlight (peaking in visible) Practice Questions: Which of these groups of particles has the greatest mass? Four individual protons Scientists estimate the central temperature of the Sun using mathematical models of the Sun. Solar energy leaves the core of the Sun in the form of photons. How does the number of neutrinos passing through your body at night compare with the number passing through your body during the day? About the same. Outward pressure and gravity are balanced in gravitational equilibrium.
