9 Why does conversion of hydrogen to helium only occur at very high

9 why does conversion of hydrogen to helium only

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________ 9.Why does conversion of hydrogen to helium only occur at very high temperatures? a)Hydrogen doesn’t form helium unless it is ionized. b)Hydrogen isn’t a gas at low temperatures. c)Short wavelength photons are needed for the conversion. d)High speeds are needed to overcome the repulsion of like charges. e)Conversion actually occurs at all temperatures. ________ 10.Which of the following canescape from inside the event horizon of a black hole? ________ 11.The expansion of the universe is accelerating. ________ 12.Why do astronomers think that some of the x-ray sources they observe are associated with black holes rather than neutron stars in orbit around a normal star? SHORT ANSWER: Complete the following. (Points for each listed) 1. List the stages of evolution for a very high mass star, like Betelgeuse. (7 points) 2.Sketch the Milky Way (edge-on and face-on) and label the following: nuclear bulge, galactic halo, disk, spheroid, spiral arms, globular clusters, the approximate location of the Sun, and the galactic center. (8 points) 3. Describe the nature of the expansion of the universe. (Hint: Think of analogies presented in class and text.) (3 points).
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  • Spring '08
  • Cosmology, Galaxies, Nobel Prize, Big Bang, Cosmic Microwave Background

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