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1
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- Today: Continue
Chapter 13, Galaxies
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2
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- Save additional Hubble Law demos and discussion for Chapter 15 on
Cosmology
- For now, can simply use as a tool to get distances to galaxies
- Evolution of Galaxies
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3
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- Galaxies live in clusters
- Rich clusters: thousands of
galaxies
- Poor clusters: Fewer than a
thousand
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4
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5
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- Galaxies live in clusters
- Rich clusters: thousands of
galaxies
- Poor clusters: Few than a
thousand
- Fundamental difference between stars and galaxies:
- Stars live isolated lives:
- They are much smaller than distance between them
- They virtually never collide
- Galaxies are not isolated
- They are only slightly smaller than the distances between them
- The can (and do) collide, and interact with gas within clusters
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6
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- Stars pass “through” each other, but orbits around galaxy
disrupted
- Gas clouds collide
- Gas stripped away from stars
- Collisions cause bursts of star formation
- Ellipticals may be those galaxies which have suffered collisions
- Spirals may be those galaxies which have not suffered collisions
- Joshua Barnes (Hawaii) and the Space Telescope Science Institute provide
a simulations of galaxy mergers.
Barnes website:
- http://www.ifa.hawaii.edu/faculty/barnes/transform.html
- Simulation of the Milky Way and its future merger with the Andromeda
galaxy: http://www.npaci.edu/online/v4.9/galaxies2.html
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7
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8
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9
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10
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11
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- Cosmological structure formation via simulations.
- This is how galaxies are thought to form from the initial conditions
following the big bang (Ch. 15).
- Check them out!
- http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/TheWorksMovies.html
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12
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- Family of Galaxies
- Properties of Galaxies
- Distance; The Hubble Law
- Size and Luminosity
- Mass (including Dark Matter)
- Evolution of Galaxies
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Notes
