Final Exam Study Guide (Answers)

Final Exam Study Guide (Answers) - ASTRONOMY 180...

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ASTRONOMY 180 INTRODUCTORY ASTRONOMY STUDY GUIDE FOR FINAL EXAM FALL 2007 NOTE: The final exam is comprehensive. You should study not only this study guide but also the other three from the previous exams. 1. How does the evolution of massive stars differ from that of lower mass stars like our Sun? There’s more burning stages – massive stars burn up to iron instead of only to carbon. (iron is the heaviest element fused in the core of any star) 2. What are white dwarfs? What are their characteristics?’ A low-mass stellar remnant that has exhausted all its thermonuclear fuel and contracted to a size roughly equal to that of the earth: they do not create energy by fusion, has a mass less than 1.4M (Chandrasekhar limit), too faint to be seen with the naked eye, emit mostly ultraviolet wavelength-light, many found in binary systems 3. What are novae? What causes them? A star in a binary system that experiences a sudden outburst of radiant energy, temporarily increasing its luminosity by a factor of between 104 and 106. Caused by the accretion of hydrogen onto the surface of a white dwarf star from it’s partner star 4. What is a supernova? How is it caused? A stellar explosion during which a star suddenly increases its brightness roughly a millionfold; it occurs when a massive star dies 5. Will our Sun become a supernova when it dies? If not, what will it become? No, because it’s not a massive star; it will become a white dwarf 6. What is the difference between Type I and Type II supernovae? Type I: A supernova occurring after a white dwarf accretes enough mass from a companion star to exceed the Chandrasekhar limit; Type II: a supernova occurring after a massive star’s core is converted to iron 7. How are the chemical elements produced during stellar evolution? H-C is produced in solar-mass stars during fusion; H-Fe produced in massive stars during fusion; heavier elements are produced in supernova explosions when the iron in their cores condenses even more so. 8. What are supernova remnants? A nebula left over after a supernova detonates 9. What is the cycle of stellar evolution? 10. What are neutron stars? What are some of their characteristics? A very compact, dense stellar remnant composed almost entirely of neutrons; remnant of Type II supernova, VERY dense, strong magnetic field, rotates rapidly 11. What are pulsars? A pulsating source associated with a rapidly-rotating neutron star with an off-axis magnetic field 12. How do pulsars generate their pulsations of energy? From their compactidness and the fact that they rotate SO QUICKLY; a rotating magnetic field explains the pulses (lighthouse model) – the fact that the rotaton axis and the magnetic axis are so far off of each other 13. What are the two major ways in which neutron stars are detected? Through x-rays and pulsars
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Final Exam Study Guide (Answers) - ASTRONOMY 180...

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