Astronomy 1021 Chapter Notes - Chapter 18: Vacuum Energy, Higgs Boson, Pseudoscience
11 May 2016
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Chapter 18: dark matter, dark energy, and the fate of the universe. Rotation curves are how we detected the dark matter problem. We use them to measure the mass of galaxies. o. Graphs representing the velocity of stars or gas clouds as a function of the distance from the center. [newton"s version of] kepler"s third law tells us how much mass is required within an orbit to result in a given velocity. So rotation curves tell us the distribution of mass within a galaxy. In the solar system, almost all mass is concentrated in the sun. Therefore, orbital speed decreases as we go farther out. For galaxies, we would expect the velocities to go down for stars near the outer edge (curve. So there must be much more mass farther out in the mw than we can see. Total visible mass in the milky way: o.
