Deck 16: Galaxies

Question 1

____ galaxies contain large clouds of gas and dust,both young and old stars,but have no obvious spiral arms or nucleus.

A) Irregular
B) S0
C) E7
D) Sa
E) E0

Answer 1

Irregular

Question 2

Based on the galaxies found in the Local Group of galaxies,the most common type of galaxy in the universe is expected to be

A) the spiral galaxies.
B) the barred spiral galaxies.
C) the dwarf elliptical galaxies.
D) the irregular galaxies.
E) the giant elliptical galaxies.

Answer 2

the dwarf elliptical galaxies.

Question 3

Most of the mass of a galaxy is contained in the

A) massive O and B stars in the galaxy.
B) neutral hydrogen gas H I regions of the galaxy.
C) ionized hydrogen gas H II regions of the galaxy.
D) dark matter halo of the galaxy.
E) disk ofstars in the galaxy.

Answer 3

dark matter halo of the galaxy.

Question 4

The rotation curve of a galaxy (orbital speed versus distance)can be used to determine

A) the colors of hot young stars in the galaxy.
B) the elements which make up the galaxy.
C) the direction in the sky of the galaxy.
D) the age of the galaxy.
E) the mass of the galaxy.

Question 5

The most luminous galaxies in blue wavelengths are

A) giant elliptical galaxies.
B) spiral galaxies.
C) dwarf elliptical galaxies.

Question 6

Galactic cannibalism refers to

A) binary galaxies.
B) the merging of galaxies.
C) galaxies drawing in gas from the intergalactic medium.
D) the destruction of a galaxy's globular clusters by the galaxies nucleus.
E) none of the above

Question 7

An irregular galaxy contains

A) mostly lower-main sequence stars and giants.
B) mostly upper main sequence stars and giants.
C) mostly upper main sequence stars and gas and dust.
D) upper and lower main sequence stars and gas and dust.
E) mostly white dwarfs and supergiants.

Question 8

Astronomers now speculate that a galaxy's shape depends on all of the following EXCEPT

A) the rate of star formation.
B) the history of past collisions.
C) the mass.
D) its direction in the sky as seen from Earth
E) All of the above are important in determining a galaxy's shape.

Question 9

A megaparsec is equivalent to

A) 3.26 light-years.
B) 206,265 light years.
C) 206,265 AU.
D) 3,260,000 light-years.
E) the diameter of the Milky Way galaxy.

Question 10

We should expect galaxies to collide with each other fairly often because

A) a galaxy's size is comparable to (but smaller than)the average distance between galaxies.
B) galaxies contain large amounts of neutral hydrogen.
C) galaxies occur in clusters.
D) a and c
E) none of the above

Question 11

If H equals 50 km/sec/Mpc,then a galaxy with a radial velocity of 2000 km/sec probably has a distance of

A) 2050 Mpc
B) 1950 Mpc
C) 40 Mpc
D) 0.025 Mpc
E) 100,000 Mpc

Question 12

If a galaxy has a radial velocity of 8000 km/sec and the Hubble constant is 70 km/sec/Mpc,what is the distance to this galaxy?

A) 8.75´10³ Mpc
B) 2.4´10⁹ Mpc
C) 5.6´10⁵ Mpc
D) 114 Mpc
E) 8.75´10^-3 Mpc

Question 13

The mass of a single galaxy might be found by

A) the direction to the galaxy in the sky
B) the rotation curve method.
C) the color of planets in our Solar System
D) any of these methods.
E) none of these methods

Question 14

An E galaxy contains

A) mostly lower-main sequence stars and giants.
B) mostly upper main sequence stars and giants.
C) mostly upper main sequence stars and gas and dust.
D) roughly equal numbers of upper and lower main sequence stars.
E) mostly white dwarfs and supergiants.

Question 15

The most massive galaxies are

A) spiral galaxies.
B) giant elliptical galaxies.
C) dwarf elliptical galaxies.

Question 16

Super massive black holes in galaxies

A) are found in their centers
B) have masses proportional to the galaxy's bulge mass.
C) cause stars near them to move at high speeds.
D) all of the above

Question 17

Which of the following could NOT be used as a distance indicator for galaxies?

A) large globular clusters
B) Planets in our own Solar System
C) Supernovae
D) Cepheid variable stars
E) Wrong.All of these could be used

Question 18

A tuning fork diagram is shown below.Which of the labeled figures represents an Sa galaxy?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 19

The dark matter in galaxies has been hypothesized to be composed of

A) neutral hydrogen clouds.
B) dust particles.
C) weakly interacting massive particles.
D) H II regions of glowing hydorgen gas.
E) all of the above

Question 20

The look-back time is

A) how long the light from an object takes to reach Earth.
B) numerically equal to the distance in light-years.
C) smaller for more distant objects.
D) all of the above
E) a and b above

Question 21

What distance method did Edwin Hubble use to determine the distance to local galaxies?

A) Hubble Law
B) Supernova observations
C) Period-luminosity relationship of variable stars
D) Parallax

Question 22

The figure shows an image of our galaxy,the Milky Way,at dust-penetrating wavelengths.It can be classified as which one of the following galactic types?

A) spiral
B) irregular
C) elliptical
D) red giant

Question 23

The Andromeda spiral galaxy is almost edge-on to us.Astronomers have detected the orbital motion of this and other such galaxies' disk material by

A) using Hubble's law.
B) the big bang theory of 3° Kelvin radiation.
C) the steady state theory.
D) measuring Doppler shifts of different parts of the disk.
E) watching the stars travel around the nucleus back to where they started.

Question 24

Until recently,most astronomers thought elliptical galaxies were shaped like oblate spheroids.

Question 25

Which one of the words below is a name for a type of galaxy in the Hubble classification system?

A) red giant
B) visual
C) spiral
D) 21 centimeter
E) statuesque

Question 26

An elliptical galaxy could

A) evolve into an irregular galaxy when it has used up all of its gas and dust.
B) be formed from the collision and merger of spiral galaxies.
C) evolve from a single spiral galaxy when the spiral has used up all of its gas and dust.
D) become a solar system some day.
E) be at the center of our Solar System

Question 27

What distance method is used to calibrate the Hubble constant in the Hubble Law?

A) Parallax
B) Sun spot observations
C) Period-luminosity relationship of variable stars
D) Spectroscopic parallax

Question 28

Edwin Hubble found the Great Nebula in Andromeda (M31 galaxy)to be very far away by ...

A) comparing absolute to apparent magnitudes of Cepheid variable stars.
B) comparing absolute to apparent magnitudes of RR Lyrae variable stars.
C) measuring parallaxes of stars in M31.
D) getting radar echoes off stars in M31.

Question 29

Elliptical galaxies contain more gas,dust,and young stars than do Sa galaxies.

Question 30

What is the primary factor in determining the classification for an elliptical galaxy?

A) Size
B) Shape
C) Mass
D) Color

Question 31

The diagram illustrates physical size and angular size as seen by the observer.We can estimate the size in light years (or parsecs or km)of M31 from

A) its angular size in degrees.
B) its distance in light years (or parsecs or km).
C) both answers a and
D) It is impossible to estimate the size of M31.

Question 32

____ is an irregular galaxy that is believed to have collided with the Milky Way galaxy's halo and is expected to merge with the Milky Way in the future.

A) The Andromeda galaxy
B) The Small Magellanic Cloud
C) M87
D) The Virgo cluster
E) The Whirlpool Galaxy

Question 33

The Milky Way galaxy is part of

A) the Virgo cluster.
B) the Large Magellanic Cloud.
C) the Small Magellanic cloud.
D) the Local Group.
E) a rich cluster.

Question 34

Starburst galaxies

A) contain a large number of very young stars but very little evidence of gas clouds.
B) contain a large number of very old stars and almost no gas or dust.
C) are often associated with a galaxy that is colliding with another galaxy.
D) are common in rich clusters of stars.
E) are composed of filaments and voids.

Question 35

What type of galaxies do astronomers believe to be the most common?

A) Elliptical
B) Spiral
C) Irregular
D) Astronomy have no idea which type of galaxy is more common.

Question 36

What factors are important when trying to classify a spiral galaxy?

A) Amount of dust and gas in the galaxy
B) Structure of the spiral arms
C) Size of the central region
D) All of the above

Question 37

What distance method is used to determine the distance to the most distant galaxies when only the redshift is known?

A) Hubble Law
B) Space probe travel times
C) Period-luminosity relationship of variable stars
D) Parallax

Question 38

Many disk galaxies,such as Andromeda and the Milky Way,are thought to have extended halos of dark matter because the disk circular orbital speed is observed to ____________ increasing distances from the disk center.

A) stay constant with
B) decrease with
C) be totally absent at

Question 39

Via the rotation curve method,we can estimate the mass of galaxies like M31 from

A) Doppler shifts of material at the edge of its disk and computing P=2pi r /v.
B) the distances of the Doppler shift points from its center
C) both answers A and B.
D) It is impossible to estimate the mass of M31.

Question 40

Cepheid variable stars are more luminous than the sun.

Question 41

Elliptical galaxies are primarily made up of massive O and B stars.

Question 42

Measuring the Doppler shift of material at various distances from the center of a galaxy can be used to construct a(n)____________________ for that galaxy.

Question 43

When a large galaxy collides with a small galaxy,the smaller galaxy may be pulled apart by tidal forces.

Question 44

____________________ galaxies have a definite disk component but contain no evidence of spiral pattern,few hot young stars,and little gas and dust.

Question 45

Due to the extremely rapid orbital velocities of material near the center of many galaxies,these galaxies are believed to contain ____________________ at their centers.

Question 46

____________________ clusters of galaxies contain closely spaced galaxies and often contain giant elliptical galaxies and a hot intergalactic medium

Question 47

The Local Group of galaxies is dominated by the presence of spiral galaxies (as the most numerous type).
.

Question 48

The look-back time is numerically equal to the distance to a galaxy in light-years.

Question 49

Some large clusters of galaxies do not appear to contain enough mass to hold them together.

Question 50

Poor clusters of galaxies often contain an excess of E and SO galaxies.

Question 51

When two galaxies collide,they pass through each other,and their stars almost never collide.

Question 52

The units on the Hubble constant are ____________________.

Question 53

If H equals 50 km/sec/Mpc,then a galaxy with a radial velocity of 50,000 km/sec will have a distance of about 1 Mpc.

Question 54

Label each galaxy in the tuning fork diagram below.Record your labels on the lines provided above or below the galaxy.

Question 55

The rotation curve method can be applied only to pairs of galaxies orbiting each other.