Astronomers Observe a Young Cluster of Stars, Where Stars with Three

question 9

Multiple Choice

Astronomers observe a young cluster of stars, where stars with three times the mass of the Sun are still on the main sequence of the H-R diagram. Yet the cluster contains two white dwarfs, each with a mass less than 1.4 times the mass of the Sun. If we can show that the white dwarfs are definitely part of the cluster, how can their presence so soon in the life of the cluster be explained?

• A) the lower the mass of a star, the more quickly it goes through each stage of its life
• B) white dwarfs are what is left over after a star explodes and throws off 90% of its mass
• C) some stars can lose a lot of mass on their way to becoming white dwarfs; thus the white dwarfs could have started out as quite massive stars
• D) stars less massive than 1.4 times the mass of the Sun go through the white dwarf stage in their lives before they become main sequence stars
• E) astronomers can think of no way to explain this problem; it has them completely baffled

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Definitions:

Semipermeable Membrane

A membrane that allows the passage of certain small molecules or ions but blocks others.

Concentration Gradient

A variation in the concentration of a substance across a distance, often leading to the diffusion of substances from an area of higher concentration to an area of lower concentration.

Diffusion

Spontaneous spreading of molecules or atoms through a fluid or gas.

Indigestible Substances

Materials that cannot be broken down and absorbed by the digestive enzymes and system of an organism, often passing through the system largely unchanged.