VA = VS Vo ( ): Star and earth are receding

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VA VS Vo () Star and earth are
receding VB VS Vo (-) Star and earth are
approaching
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Doppler-shift formula
1 Å 1 x 10-10 m c 2.9989 x 108 m/s
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Doppler Effect and Line Broadening
Line broadening can be due to a variety of causes

• Thermal broadening
• Rotational broadening
• Collisional broadening
• Zeeman effect (magnetic broadening)

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Rotational Broadening
Rotation will also cause broadening of spectral
lines through the Doppler effect
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Comparison Values

• Orbital velocity of earth
• 2.98 x 104 m/s
• Earth-sun distance
• 1.496 x 1011 m