Red Giants and Their Evolution

Red giants are stars in a late stage of stellar evolution, occurring after the main-sequence phase when hydrogen in the core is depleted. The core becomes helium-rich, and the star expands dramatically, cooling and taking on a red appearance. The Sun will eventually become a red giant, engulfing inner planets. Red giants spend a small fraction of their life in this phase before becoming white dwarfs. Notable red giants include Betelgeuse.

What happens to a star when it exhausts its hydrogen supply in the core?

• It becomes a black hole.

• Fusion stops and the star expands.

• It immediately explodes.

• It turns into a planet.

What is the core of a red giant primarily composed of?

• Carbon dioxide

• Liquid hydrogen

• Solid iron

• Ionized helium

How does the atmosphere of a red giant change as it expands?

• It turns blue and shrinks.

• It cools down and becomes redder.

• It becomes hotter and denser.

• It becomes transparent.

In how many billion years is the Sun expected to reach the Earth's orbit as a red giant?

• 1-2 billion years

• 3-4 billion years

• 5-6 billion years

• 7-8 billion years

What happens to the outer layers of a star when it is powered by helium?

• They expand and cool down.

• They return to normal, shrink, and get hotter.

• They explode.

• They become transparent.

What percentage of their lives do stars typically spend in the red giant phase?

• 1%

• 50%

• 10%

• 25%

Which of the following is a well-known red giant star?

• Vega

• Polaris

• Betelgeuse

• Sirius

What is the next evolutionary stage for a red giant after it exhausts its fuel?

• It becomes a neutron star.

• It explodes as a supernova.

• It turns into a black hole.

• It becomes a white dwarf.

What is the main difference between red giants and red supergiants?

• Red supergiants are more massive.

• Red giants are more luminous.

• Red giants are hotter.

• Red supergiants are smaller.

What is the fate of more massive main-sequence stars compared to less massive ones?

• They turn into planets.

• They become red giants and then white dwarfs.

• They evolve into red supergiants.

• They remain as main-sequence stars.