I. Stars. The Brightness of Stars - Star: A hot glowing sphere of gas that produces energy by fusion. - Fusion: The joining of separate nuclei. Common in nature, but not on Earth. Variables which affect a star’s brightness: Star size Distance from Earth Star temperature.
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-Star: A hot glowing sphere of gas that produces energy by fusion.
-Fusion: The joining of separate nuclei. Common in nature, but not on Earth.
Dust and gas particles exert a gravitational force on each other which keeps pulling them closer together.
Orion NebulaB. The Origin of Stars
At 10,000,000o C fusion takes place and energy radiates outward through the condensing ball of gas.
Another view of OrionMore Nebulas
Star expands and becomes a red giant
Red GiantC. Stellar Evolution
As the core uses up its helium supply, the outer layers escape into space and the remaining core is white hot and called a white dwarf.
White dwarfsStellar Evolution
Smaller stars become neutron stars and most massive will collapse into a black hole.
Neutron StarMore Stellar Evolution
The actual brightness is average for a star of its average size.A. The Sun and You
Radiation zone: Energy bounces back and forth before escaping.
Convections zone: Cooler layer of gas that is constantly rising and sinking.2. Layers of the Sun (Fig. 20.9)
Chromosphere: Active layer which is home to many significant displays.Anatomy of Sun
Sunspot Maximum: Time of many large sunspots.
Sunspot Minimum: Time of few sunspots.Cycle of Solar Activity
Milky Way: Our galaxy which contains about 200 billion stars and many nebulas
Spiral GalaxiesA. Earth’s Galaxy—and Others
-Contain mostly older and dimmer stars.Elliptical Galaxies
Arms are made up of stars and dust
Two spiral galaxies!!Spiral Galaxies
Doppler EffectC. The Doppler Shift
If a star is traveling away (as most are) the lines will move toward the red part of the spectrum.C. The Doppler Shift
Quasars: Star like objects at the outskirts of the universe which give off tremendous energy. C. The Red Shift