Astronomy Stars and Stellar Evolution

Question 1

What is the Hertzsprung-Russell diagram used for?

Accepted Answer

Plotting stars by luminosity versus temperature to reveal stellar classification and evolutionary stages

Answer

The H-R diagram plots stars' luminosity against surface temperature/spectral type, revealing distinct groupings (main sequence, red giants, white dwarfs) and showing how stars evolve through different stages.

Question 2

What process powers stars on the main sequence?

Accepted Answer

Nuclear fusion of hydrogen into helium in the core

Answer

Main sequence stars are powered by hydrogen fusion (proton-proton chain or CNO cycle) in their cores, converting hydrogen to helium and releasing energy according to E=mc².

Question 3

What is a neutron star?

Accepted Answer

An extremely dense remnant of a massive star's core after a supernova explosion

Answer

A neutron star forms when a massive star's core collapses during a supernova, compressing matter so densely that protons and electrons merge into neutrons. A typical neutron star is about 20 km in diameter but contains 1-2 solar masses.

Question 4

What determines whether a dying star becomes a white dwarf, neutron star, or black hole?

Accepted Answer

The mass of the star's remaining core after its outer layers are expelled

Answer

Core mass determines the fate: below ~1.4 solar masses (Chandrasekhar limit) becomes a white dwarf, between ~1.4-3 solar masses becomes a neutron star, above ~3 solar masses (Tolman-Oppenheimer-Volkoff limit) collapses into a black hole.

Question 5

What is a supernova?

Accepted Answer

A catastrophic explosion marking the death of a massive star, briefly outshining an entire galaxy

Answer

A supernova occurs when a massive star exhausts its fuel and its core collapses, or when a white dwarf accretes enough matter to exceed the Chandrasekhar limit, resulting in a catastrophic explosion that disperses heavy elements into space.

Astronomy Practice Test

Astronomy Practice Test

Astronomy Stars and Stellar Evolution