July 18th, Lecture 5 continuation on another date.docx

2 Pages
Unlock Document

University of Toronto St. George
Astronomy & Astrophysics
Marija Stankovic

July 18 , Lecture 5 Continuation, AST201H1 Sun does not burn. To get particles to overcome their mutual repulsion, they have to have a lot of energy and be very hot. Gas is hydrogen. Need to bind them, bring them close, electromagnetic force (same charge) so will try to repel. Two protons will try to repulse each other. At low speeds, electromagnetic repulsion prevents the collision of nuclei. At high speeds, nuclei come close enough for the strong force to bind them together. Sun’s core is more than 15 million Kelvin. Need this to bring those protons together. Nuclear Fusion. Start off with four protons, combine together, what is produced is a new nucleus that has two protons and two neutrons. This fusion reaction is called the proton-proton or the “p-p” chain. Nuclear fusion- smashing nuclei together to form larger nuclei. Two nuclei of hydrogen to make helium. Can only happen in the universe, centers of stars. Or explosions called supernova explosions. Don’t have enough energy to make this happen on Earth. Nuclear fission- breaking nuclei apart to form smaller nuclei. Same as nuclear plants. The p-p chain has several intermediate steps. Step 1: two protons fuse to make a deuterium nucleus (1 proton and 1 neutron). Heavy hydrogen. These anti-electron, will react something else and will produce gamma rays. Step 2: Other Protons come in to make Helium-3. Two protons and one neutron. Step 3: Smash Helium-3 together to make Helium-4 and return the protons. Anti-matter. Neutrino shooting through our bodies. Only interact weakly with gravi
More Less

Related notes for AST201H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.