CH 23 HW

Where are most of the bright stars in our Galaxy located?

In the Galactic disk.

Where are globular clusters mainly found?

In the Galactic halo.

What method did Shapley use to measure distances to globular clusters?

Comparison of the absolute and apparent magnitudes of variable stars.

What is a tightly packed group of old stars called?

A globular cluster.

What type of galaxy is the Milky Way?

A spiral galaxy.

What is the expected orbit behavior of stars near the center of the Milky Way?

They can have orbits highly inclined to the galactic plane.

Which property is NOT helpful in determining if a newly discovered variable star is a Cepheid or an RR Lyrae?

Distance.

Where do the first stars that formed in the Milky Way orbit now?

Have random orbits in the halo.

Where are large dust clouds predominantly located in the galaxy M51?

Within or on the edges of the spiral arms.

Where are ionization nebulae predominantly found in the galaxy M51?

Within or on the edges of the spiral arms of the galaxy.

Why are ionization nebulae so bright?

They are regions where gas is ionized by hot, young stars.

Where would a telescope searching for newly formed stars make the most discoveries?

Within a spiral arm.

In what form does most of the mass of the Milky Way exist?

Dark matter.

What does the Galaxy Rotation Curve indicate?

Far from the center, the Galaxy rotates more rapidly than expected based on the light we see.

What was the initial expectation about the orbital speeds of stars in the Milky Way?

Stars far from the center should orbit more slowly than stars closer to the center.

What provides evidence that a supermassive black hole is at the center of the Milky Way?

The orbits of stars very close to the center.

What evidence does rapid motion of gas in the galactic center suggest?

There must be a large central mass causing such rapid motion.

What is the main evidence for a black hole at the Galactic center?

Stars near the center are orbiting some unseen object.

In which region of the galaxy is the Sun located?

Galactic disk.

Why are infrared and radio telescopes preferred for studying the galactic center?

Dust in the plane of the Milky Way obscures observations at other wavelengths.