Cepheid Variables Pulsate Because They Contain a Layer That Alternately

question 114

Multiple Choice

Cepheid variables pulsate because they contain a layer that alternately blocks photons while heating and then becomes transparent to photons as it expands. What substance composes this layer?

• A) hydrogen
• B) deuterium
• C) ionized helium
• D) twice ionized carbon

---

Definitions:

Hydrologic Cycle

The continuous movement of water on, above, and below the surface of the Earth, including processes such as evaporation, precipitation, and runoff.

Mid-Ocean Ridges

Undersea mountain ranges where new oceanic crust is formed through volcanic activity and seafloor spreading.

Hot Springs

Natural springs that discharge water heated by geothermal processes from the Earth's interior.

Planet's Formation

The process by which a planet forms from the gas and dust surrounding a young star, typically through the accretion of material.