ASTR 124 : Stars Galaxies and the Universe

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ASTR 124 Stars Galaxies and the Universe

• Introduction The Big Picture

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Hierarchy of structures

• Nuclei (particles)
• Atoms
• Stars/Planets
• Galaxies
• Universe

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Atoms Nuclei protons neutrons Electrons
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p.418a
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Solar magnetic surface storm
Earth
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Scale of the Solar System

• Earth-moon system..
• The sun as an orange.
• The nearest star
• The galaxy !

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Our Galaxy The Milky Way

• Milky way galaxy is a complex system
• 1011 stars ( planets?)
• Each with life cycle birth/life/death
• Material between the stars
• Tenuous gas clouds diffuse

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New star-formation region
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Two young star clusters
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Slow death of low mass star
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Our Galaxy
Earth 100 nm virus Sun
10 µm cell Earth orbit
¼ cm pin head Solar system 20
cm saucer Nearest star 250 m
lawn
Solar system
Galaxy Center
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The Population of Galaxies

• Galaxies are a diverse population
• Different sizes shapes motions
• ? different histories?
• They tend to form groups
• pairs ? clusters some collide and merge

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Interacting galaxies
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Galaxies to the horizon

• The Universe is filled with galaxies
• 1011 galaxies visible
• More distant ones appear younger
• look-back time due to finite light speed

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SDSS ? million galaxies
3 billion light years (20 to the edge)
Our galaxy is here
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Hubble Deep Field 1500 galaxies Sky area
2.52.5 arcmin pinhead _at_ arms-length
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A 1689 Rich galaxy cluster 2 Gly
distant Gravitational lens
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13.7 Gly
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The Visible Universe
MW galaxy 20 m class room
MW galaxy 20 m class room Local
group 600 m central grounds Virgo
cluster 15 km Walmart Coma cluster
100 km Culpeper
Our Galaxy