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Variable Stars and Their Pulsations
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What is the primary mechanism driving the pulsations in Cepheid variable stars?
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A
Thermal expansion and contraction of the outer layers
💡 Explanation:
Cepheid variable stars pulsate due to a delicate balance between the outward pressure from radiation and the inward pull of gravity. As the star expands, it cools and the radiation pressure decreases, causing it to contract. This contraction heats the star, increasing the radiation pressure and causing it to expand again, repeating the cycle.