Measuring Distances To Galaxies

Measuring Distances To Galaxies - Measuring Distances To...

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Measuring Distances To Galaxies Introduction: This week, the course will cover: The structure of the Milky Way Galaxy. The life cycle of stars. The hierarchy of the universe. The origin of the universe. In this week's lecture, I would like to expand upon one of 'The hierarchy of the universe' sections of the textbook which I had some personal involvement in. As a graduate student, I worked with my thesis adviser investigating the velocity dispersions of elliptical galaxies and which resulted in a new distance indicator called the 'Faber-Jackson Relation'. My Ph.D. Thesis involved using a different distance indicator to determine how fast our galaxy was moving with respect to more distant galaxies. Lecture: Measuring distances to galaxies is critical for understanding the age, structure, and dynamics of the universe. Using distance indicators for nearby galaxies and their recession velocities, astronomers can determine the Hubble Constant, which measures how fast the universe is currently expanding. Using a different distance indicator for more distant galaxies, astronomers can determine q 0 , which measures if the expansion rate is increasing or decreasing, i.e., is the cosmic foot on the accelerator or the brake? More recently, using this distance indicator on very distant galaxies, astronomers have found evidence for the Cosmological Constant or what is now called 'Dark Energy'. Unfortunately it is very hard to find good distance indicators for galaxies. The textbook discusses Cepheid variables, the Tully Fisher relation, and White Dwarf Supernovae. The Cepheid variables distance indicator was used by Hubble Space Telescope astronomers to make the best determination of the Hubble Constant. The White Dwarf Supernovae distance indicator was used to make the best determination of q 0 and to discover evidence for 'Dark Energy'. The Tully Fisher relation has been widely used to measure distances to spiral galaxies which are too distant to find Cepheid variables in. When looking at the spatial distribution of galaxies, we see that our own galaxy is located near the edge of the Virgo Supercluster and that the universe is filled with even more impressive clusters of galaxies and superclusters. We would expect that the gravitational force of these mass concentrations should have an impact on the radial
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This note was uploaded on 04/07/2010 for the course SCI 151 taught by Professor Jackson during the Fall '09 term at University of Phoenix.

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Measuring Distances To Galaxies - Measuring Distances To...

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