How Do We Determine the Amount of Dark Matter in Elliptical

question 71

Multiple Choice

How do we determine the amount of dark matter in elliptical galaxies?

• A)We measure how fast the galaxy rotates as a whole.
• B)We measure the broadening of the galaxy's absorption lines to infer the speeds of stars at different distances from the galactic center.
• C)We count the number of stars in the galaxy. Combining this with the galaxy's volume, we can calculate the galaxy's density.
• D)We measure the orbital velocities of star- forming gas clouds in the outer portion of the galaxy.
• E)We search for dark lanes of dust and black holes within the galaxy.

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Definitions:

Splitters

Refers to scientists, especially taxonomists, who prefer to classify organisms into many fine categories based on small differences.

Naming Species

The process of systematically identifying and classifying organisms into groups based on shared characteristics, following a standard set of rules.

Lumping

The practice in taxonomy of grouping together several previously separate species into one broader category.

Obsidian

A naturally occurring volcanic glass, used by ancient people for making sharp tools and ornaments.