That life would be impossible without energy from the Sun
That Earth formed at the same time as the Sun
That the carbon, oxygen, and many elements essential to life were created by nucleosynthesis in stellar cores
That the Sun formed from the interstellar medium: the "stuff" between the stars
That the Universe contains billions of stars
Nuclear fusion and gravitational contraction
Nuclear fission and gravitational contraction
Nuclear fusion and nuclear fission
Chemical reactions and gravitational contraction
Nuclear fusion and chemical reactions
Between 500 and 1,000 solar masses
Between 150 and 500 solar masses
Between 10 and 150 solar masses
Between 2 and 100 solar masses
Between 2 and 50 solar masses
Molecular clouds do not have enough material to form such massive stars.
They would fragment into binary stars because of their rapid rotation.
They would generate so much power that they would blow themselves apart.
They shine exclusively at X-ray wavelengths and become difficult to detect.
They are not bright enough to be seen nearby.
Degeneracy pressure varies with the temperature of the star.
Degeneracy pressure can halt gravitational contraction of a star even when no fusion is occurring in the core.
Degeneracy pressure keeps any protostar less than 0.08 solar mass from becoming a true, hydrogen-fusing star.
Degeneracy pressure arises out of the ideas of quantum mechanics.
It will become a white dwarf.
It will become a neutron star.
It will become a black hole.
It will slowly evaporate to nothing.
It will remain a brown dwarf forever.
Its core contracts, but its outer layers expand and the star becomes bigger and brighter.
It contracts, becoming smaller and dimmer.
It contracts, becoming hotter and brighter.
It expands, becoming bigger but dimmer.
Its core contracts, but its outer layers expand and the star becomes bigger but cooler and therefore remains at the same brightness.
The outer layers of the star are no longer gravitationally attracted to the core.
Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward.
Helium fusion in the core generates enough thermal pressure to push the upper layers outward.
Helium fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward.
The internal radiation generated by the hydrogen fusion in the core has heated the outer layers enough that they can expand after the star is no longer fusing hydrogen.
Varies depending on the reaction
None of the above
The core quickly heats up and expands.
The star breaks apart in a violent explosion.
The core suddenly contracts.
The core stops fusing helium.
The star starts to fuse helium in a shell outside the core.
A disk of gas surrounding a protostar that may form into planets
What is left of the planets around a star after a low-mass star has ended its life
The expanding shell of gas that is no longer gravitationally held to the remnant of a low-mass star
The molecular cloud from which protostars form
The expanding shell of gas that is left when a white dwarf explodes as a supernova
It contracts from a protostar to a main-sequence star.
It breaks apart in a violent explosion.
It becomes a white dwarf.
It becomes a neutron star.
None of the above
Red giant, protostar, main-sequence, white dwarf
White dwarf, main-sequence, red giant, protostar
Protostar, red giant, main-sequence, white dwarf
Protostar, main-sequence, white dwarf, red giant
Protostar, main-sequence, red giant, white dwarf
The process by which helium is fused into carbon, nitrogen, and oxygen
The process by which carbon is fused into nitrogen and oxygen
A type of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts
The period of a massive star's life when carbon, nitrogen, and oxygen are fusing in different shells outside the core
The period of a low-mass star's life when it can no longer fuse carbon, nitrogen, and oxygen in its core
The core contracts and becomes a white dwarf.
The core contracts and becomes a ball of neutrons.
The core contracts and becomes a black hole.
The star explodes violently, leaving nothing behind.
Gravity is not able to overcome neutron degeneracy pressure.
All stars that are red in color
All stars that are yellow in color
Stars that are at least several times the mass of the Sun
Stars that are similar in mass to the Sun
Stars that have reached an age of 10 billion years
Always a white dwarf
Always a neutron star
Always a black hole
Either a white dwarf or a neutron star
Either a neutron star or a black hole
It occurred only a few dozen light-years from Earth.
It provided the first evidence that supernovae really occur.
It provided the first evidence that neutron stars really exist.
It was the first supernova detected in nearly 400 years.
It was the nearest supernova detected in nearly 400 years.
It doesn't make sense to find a giant in a binary star system.
The odds of ever finding two such massive stars in the same binary system are so small as to make it inconceivable that such a system could be discovered.
The two stars in a binary system should both be at the same point in stellar evolution; that is, they should either both be main-sequence stars or both be giants.
The two stars should be the same age, so the more massive one should have become a giant first.
A star with a mass of 15Msun is too big to be a main-sequence star.