What happens inside a Sun-like star when it runs out of hydrogen in its core?

The star immediately explodes as a supernova The core contracts and heats up, and hydrogen ignites in a shell around the core The star cools down and slowly fades away The star begins fusing iron in its core

Why does a star's outer envelope expand so dramatically when it becomes a red giant?

The star absorbs material from surrounding space that makes it grow Dark energy inside the star pushes the layers apart Shell hydrogen burning produces more energy than before, and the increased pressure pushes the outer layers outward The star loses gravity as it ages, allowing its layers to float outward

Approximately how large does a Sun-like star become when it expands into a red giant?

About 2 times its current size — just slightly larger About 1 million times its current size — it would fill the entire inner solar system About 100 to 200 times its current size — large enough to engulf the inner planets About 10 times its current size — roughly as large as Jupiter

What is the helium flash?

A visible explosion on the surface of a red giant that can be seen from Earth The sudden explosive onset of helium fusion in the core of a Sun-like star when the core temperature reaches about 100 million Kelvin The moment when a star first starts to glow during its protostar phase A burst of light emitted when a star's outer layers first expand into a red giant

What does helium fusion in a star's core produce?

Nitrogen and neon Iron and silicon More hydrogen — fusion reverses at high temperatures Carbon and oxygen, through the triple-alpha process

What is an asymptotic giant branch (AGB) star?

A young star just beginning hydrogen fusion on the main sequence A star that has just ignited helium fusion for the first time A late stage of evolution for low and medium mass stars, after helium in the core is exhausted, when the star expands even further and pulsates The stage when a massive star begins fusing silicon in its core

Why does a red giant appear red even though its total light output is much greater than before?

Red giants contain large amounts of iron oxide (rust) on their surfaces The outer layers have expanded and cooled significantly, shifting the peak emission toward red wavelengths Red giants are in a part of the galaxy where red light from other stars shines on them Red giants produce red light because they are fusing helium instead of hydrogen

How does the core behave while the outer layers of a star are expanding into a red giant?

The core expands along with the outer layers to maintain equilibrium The core remains unchanged while the outer layers expand The core contracts and heats up as outer layers expand — the two regions behave in opposite ways The core cools down and contracts while the outer layers also cool

After the helium flash, what brief stable phase does a Sun-like star enter?

The white dwarf phase, where the star cools quietly for billions of years The main sequence, where the star fuses hydrogen in the core again The supernova phase, where the star explodes The horizontal branch — a phase of stable helium core burning at roughly constant luminosity

What happens to the material blown off by an AGB star in stellar winds?

It falls back onto the star and is recycled into more fuel It forms new planets around the dying star It forms a planetary nebula and eventually gets mixed back into the interstellar medium, enriching it with carbon and other elements It is pulled away by the gravity of any nearby stars