Astronomy 106 Quiz 18

Astronomy 106 Quiz 18

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

____ 1. Who discovered that Cepheid variables can be used a distance indicator?

____ 2. How are globular clusters distributed in the Milky Way?

a.	form a "halo" outside the Milky Way, and are distributed symmetrically around its center.
b.	concentrated in the plane of the Milky Way
c.	concentrated in the central core of the Milky Way.
d.	distributed in a ring around the edge of the Milky Way.
e.	distributed completely at random

____ 3. Why are main sequence stars not suitable for determining the distance to galaxies?

a.	the HR diagram does not work at galactic distances
b.	galaxies other than the Milky Way do not contain main sequence stars.
c.	main sequence stars in distant galaxies are too intrinsically faint to be useful as distance indicators.
d.	the color of main sequence stars is so distorted by intergalactic material that their true spectral classes can not be determined.
e.	the implicit assumption in the question is wrong. Main sequence stars are very useful in the determination of the distances to external galaxies.

____ 4. How are open clusters distributed in the Milky Way?

a.	completely random distribution.
b.	concentrated in the plane of the Milky Way
c.	form a "halo" outside the Milky Way, and distributed symmetrically around its center.
d.	concentrated in the central core of the Milky Way.
e.	distributed in a ring around the edge of the Milky Way.

____ 5. Heber Curtis' model of the universe:

a.	only one galaxy with the sun in the center.
b.	only one galaxy with the sun near the edge of the galaxy.
c.	many galaxies with the sun near the edge of our galaxy.
d.	many galaxies with the sun in the center of our galaxy.
e.	a spherical distribution of stars spreading out to an infinite distance.

____ 6. What is the zone of avoidance?

a.	another word for *dark matter*; matter with gravitational influence, but not detectable at any wavelength.
b.	An area on the celestial sphere where no stars can be seen
c.	That portion of the celestial sphere below the southern horizon which can never be seen from our latitude.
d.	A region along the band of the Milky Way where no spiral nebulae (galaxies) can be seen.
e.	The space between the allowed electron orbits of the Bohr hydrogen atom; electrons are never found in this region.

Astronomy 106 Quiz 18

Answer Section

MULTIPLE CHOICE

1. D

2. A

3. C

4. B

5. D

6. D