Deck 25: Galaxy Clusters and the Structure of the Universe

Question 1

There is often a giant,dominant elliptical at the center of galactic clusters.It is thought to arise from

A)A collection of black holes at the center
B)Large amounts of hydrogen gas collecting in the core
C)Gravitational effects of the local supercluster
D)Tidal interactions among members of the cluster

Answer 1

Tidal interactions among members of the cluster

Question 2

The Coma cluster is

A)Poor and regular
B)Rich and regular
C)Poor and irregular
D)Rich and irregular

Answer 2

Rich and regular

Question 3

Which of the following types of galaxies make up the majority of the members of the local group?

A)Elliptical
B)Spiral
C)Barred spiral
D)Irregular

Answer 3

Irregular

Question 4

The model of cluster formation in which galaxies form first and then collect into clusters is called the

A)Pancake model
B)Explosion model
C)Hierarchical clustering model
D)Top-down model

Question 5

Evidence for dark matter surrounding massive galactic clusters comes from what observation?

A)Huge galactic jets that contain large quantities of dark matter.
B)Motions of individual galaxies toward an invisible gravitational source.
C)Colliding neutron stars,with the collision energy creating dark matter.
D)Arcs caused by a gravitational deflection of light.

Question 6

How does the distance to the Virgo Cluster compare with the size of the Local Group?

A)The Local Group is larger than the distance to the Virgo Cluster
B)The distance to the Virgo Cluster is larger than the size of the Local Group
C)The two are the same
D)The distance to the Virgo Cluster is entirely unknown

Question 7

The central regions of large clusters contain mostly S0 and elliptical galaxies.Why?

A)Tides there have stripped normal spirals of their outer parts
B)Galaxies are still forming there
C)They are too distant for us to see other types of galaxies
D)S0 galaxies are shot out of other galaxies in clusters

Question 8

Evidence for invisible matter between galaxies in clusters (intracluster matter)is provided by

A)The rotation curves of clusters that are flatter than Keplerian
B)Absorption lines in the spectra of cluster members
C)Star formation regions between galaxies in clusters
D)X-ray emission from a halo of gas centered on the cluster

Question 9

Which of the following statements about galaxies is true?

A)Most galaxies are well isolated from other galaxies
B)Most galaxies occur in isolated pairs
C)Galaxies are found both in small groups and large clusters
D)Galaxies are uniformly distributed throughout the universe

Question 10

High density regions in galactic clusters tend to be dominated by what galaxy type?

A)Normal spiral
B)Barred spiral
C)Elliptical
D)Irregular

Question 11

Low density regions between clusters tend to be dominated by what types of galaxies?

A)Spirals and ellipticals.
B)Ellipticals and irregulars
C)Spirals and ellipticals
D)Irregulars and spirals

Question 12

What type of galaxy is frequently found at the center of a rich cluster of galaxies?

A)Giant elliptical
B)Spiral
C)Dwarf elliptical
D)Irregular

Question 13

A rich cluster of galaxies contains about _____ galaxies.

A)50
B)1000
C)100,000
D)1,000,000

Question 14

The largest,brightest galaxies in the Local Group are

A)Spirals
B)Irregulars
C)Ellipticals
D)Quasars

Question 15

The Local Group is

A)A group of about 50 galaxies containing the Milky Way galaxy
B)A supercluster that contains the Virgo Cluster
C)An example of a void
D)A large supercluster of galaxies centered on the Milky Way

Question 16

Which of the following statements best describes the distribution of galaxies in the universe?

A)The galaxies lie on sheets surrounding empty regions
B)The galaxies are distributed uniformly in space
C)There are a few large clusters of galaxies with nothing in between
D)There are many clusters near us in space,but nothing beyond

Question 17

Which of the following statements about the Local Group of galaxies is NOT true?

A)It contains a few dozen galaxies
B)The Milky Way is one of two large spiral galaxies in the Local Group
C)The Virgo cluster is part of the Local Group
D)Some members of the Local Group are in orbit about the Milky Way