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Transcript
Learning Objectives: • Where do the elements come from? • What can we learn from telescopes? • How do heavy elements form? The equation below shows a typical fusion reaction that occurs in stars. It is interesting to note that the overall mass of the reactants is bigger than the overall mass of the products. Drag the labels in the correct place. What happens to the missing mass? Why do you think two anti-electrons are released? 4 H He 2 e 1 1 What happens to the Helium Ionprocess? reactants in this Where do the elements come from? 4 2 Positron 0 1 Is this equation balanced? In what sense is/isn’t it? Hydrogen Ion Einstein discovered that: E mc ALT + Click to edit this text, or delete and use INK for PowerPoint (the interactive pen in the bottom left corner) to write your conclusions! 2 What do E, m and c mean? Use the information below and the above equation to work out the energy released by the fusion reaction 4 H He 2 e 1 1 4 2 0 1 What other reactions could Reactants = Would Products occur inmass a star? they mass = produce more 6.69x10-27 kg or less energy? 6.64x10-27 kg Where do the elements come from? Do you think this energy is large or small? Why? How many reactions like this one do you think occur in a star every second? What can you notice about the Binding Energy per Nucleon in different elements? Which is the most stable element? Why did you choose that one? Where do the elements come from? Average Binding Energy per Nucleon (1.66 x 10-13 J) The binding energy per nucleon is a measurement of the energy that holds each particle (nucleon) in the nucleus of an atom. Compare the B.E. Per Nucleon of He and H. What can you notice? Could you use this graph to predict the energy released by nuclear reactions? Explain your answer Average Binding Energy per Nucleon (1.66 x 10-13 J) Drag the labels in the correct place on the graph. In this region nuclear fission happens In this region nuclear fusion happens In this region nuclei are very stable The next three images show the same region of rapid star formation in the Orion Nebula and the wavelengths emitted by the cosmic gas surrounding these newly born stars. Use the information in these images to discuss the possible consequences of the presence of these molecules in such regions. What can we learn from telescopes? What types of molecules are these? What would your Biology teacher associate these molecules with? What can we learn from telescopes? What elements can you spot in this emission spectrum? What would you Chemistry teacher associate these molecules with? Orion Nebula (Herschel Space Observatory) Do you think Scientists expected to find these molecules in young star forming regions? Explain your answer. Would you expect to find heavier elements like Iron in this region? Why? What can we learn from telescopes? Were you expecting to find these molecules in young star forming regions? What other elements are formed in a young star? What do the sharp peaks in the spectral graph mean? Which molecule is most abundant in this star forming region? Why are these molecules important? Why are Scientists interested in them? Do you think Scientists are looking at a particular part of the EM Spectrum here? Why? What can we learn from telescopes? Orion Nebula (Herschel Space Observatory) What is this type of star called? What elements would you expect this star to produce when it comes to the end VY Canisof Majoris (Herschel) its life? What can we learn from telescopes? In what stage of its life is this star? What will happen to this star eventually according to the theory of evolution of stars? Why is this called Tycho’s Supernova? Would we be able to see these Supernova remnants, if we used the same instruments Thyco used? Why? Tycho's Supernova How do heavy elements form? What elements can you spot in this emission spectrum? Compare the elements from this supernova with the elements surrounding young stars. What can you notice? Complete the postcard below to tell Tycho Brahe how much we have discovered about “his” Supernova and other stars with modern telescopes Dear Tycho, You wouldn't believe what we have discovered about Supernovae and stars with modern telescopes... Tycho Brahe Benátky nad Jizerou Czech Republic 11th How do heavy elements form? November 1572 Back Front of of Postcard Postcard • Where do the elements come from? A variety of elements are found in regions surrounding relatively young stars • What can we learn from telescopes? Modern telescopes (especially space telescopes) allow us to observe all the EM waves emitted by stars, not just visible light • How do heavy elements form? Heavy elements like Iron are found in remnants of dead stars (Supernovae) and this suggests that such elements form in the last stages of the life of a star Learning outcomes