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Starting Ch.9: Interstellar Medium
•Since stars die, new ones must somehow be born
•They must be made out of material like star:
–H, He, plus a little heavier elements
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•Three types of interstellar “nebulae” or clouds
–Emission nebulae -- Glow with emission lines
–Reflection nebulae -- Reflect starlight
–Dark nebulae -- seen in silhouette
From our text:  Horizons, by Sees