How Did Astronomers Determine That Elliptical Galaxies Are Composed Mostly

question 98

Multiple Choice

How did astronomers determine that elliptical galaxies are composed mostly of dark matter?

• A) They measured the velocities of stars in the inner regions of the galaxies.
• B) They measured the rotation rates of gas as a function of distance from the centers of the galaxies.
• C) They measured the amount of gravitational pull elliptical galaxies have on companion galaxies.
• D) They assumed that the proportion of dark matter was roughly the same as in spiral galaxies.
• E) They measured the X-ray emission from hot gas gravitationally bound to the galaxies.

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Definitions:

Variable Components

Parts of a cost or expense that change in proportion with changes in the level of business activity or production volume.

Fixed Components

The elements of a business's costs that remain constant regardless of the level of production or sales activity.

Contribution Margin

The amount by which sales income exceeds variable expenses, which is utilized to pay off fixed expenses and create profit.

Variable Costs

Expenses that vary in direct proportion to changes in production or sales volume, such as raw materials and direct labor costs.