Astronomy In Class Quiz

Front 1

The lowest-mass stars cannot become giants because

Back 1

they cannot heat their centers hot enough

Front 2

A planetary nebula is

Back 2

the expelled outer envelope of a medium mass star

Front 3

Massive stars cannot generate energy through iron fusion because

Back 3

iron is the most tightly bound of all nuclei.

Front 4

Stars with masses between 0.4 M and 4 M

Back 4

undergo thermonuclear fusion of hydrogen and helium, but never get hot enough to ignite carbon.

Front 5

A type-II supernova

Back 5

is characterized by a spectrum that shows hydrogen lines.
occurs when the iron core of a massive star collapses.

Front 6

Synchrotron radiation is produced

Back 6

in supernova remnants.

Front 7

As material leaves an expanding star and begins to fall into a white dwarf

Back 7

an accretion disk will form around the white dwarf.

Front 8

A white dwarf is composed of

Back 8

carbon and oxygen nuclei and degenerate electrons.

Front 9

A planetary nebula

Back 9

produces an emission spectrum

Front 10

A typical planetary nebula will be visible for about

Back 10

50,000 years.

Front 11

We know that the central object in a planetary nebula has a surface temperature of at least _______________ K because the nebula contains large amounts of ionized hydrogen.

Back 11

25,000 K

Front 12

As a white dwarf cools its radius does not change because

Back 12

pressure does not depend on temperature for a white dwarf because the electrons are degenerate.

Front 13

TRUE or FALSE: Stars less massive than 0.4 solar mass never become giant stars

Back 13

True

Front 14

TRUE or FALSE: Planetary nebulae are sites of planet formation.

Back 14

False

Front 15

TRUE or FALSE: Once a star ejects a planetary nebula, it becomes a white dwarf.

Back 15

True

Front 16

TRUE or FALSE: Because massive stars have more gravitational energy than the sun, they can fuse heavier nuclear fuels.

Back 16

True

Front 17

TRUE or FALSE: The sun will eventually become a supernova.

Back 17

False

Front 18

TRUE or FALSE: Type II supernovae are believed to occur when the core of a massive star collapses.

Back 18

True

Front 19

TRUE or FALSE: Synchrotron radiation occurs when high speed electrons move through a magnetic field.

Back 19

True

Front 20

TRUE or FALSE: A Type II supernova produces a planetary nebula

Back 20

False

Front 21

TRUE or FALSE: An accretion disk can grow hot enough to radiate X rays

Back 21

True

Front 22

TRUE or FALSE: A nova destroys the star and leaves behind a white dwarf.

Back 22

False

Front 23

Which of the following is not a characteristic of the stars of the disk component of our galaxy?

Back 23

randomly inclined orbits.

Front 24

Our galaxy is suspected to be surrounded by a galactic corona because the disk of the galaxy

Back 24

rotates faster than expected in its outer region.

Front 25

Younger stars have more heavy elements because

Back 25

heavy elements were made in previous generations of stars.

Front 26

The first stars to form in our galaxy

Back 26

had highly elliptical orbits

Front 27

Good spiral tracers are all

Back 27

Very young and very luminous

Front 28

Radio maps of our galaxy show spiral arms because the

Back 28

gas in spiral arms is more dense than it is between the spiral arms.

Front 29

The energy source at the center of our galaxy

Back 29

is not visible at optical wavelengths.
produces gamma rays.
must be less than 10 AU in diameter.

Front 30

The magnetic field of the galaxy

Back 30

traps cosmic rays in the disk of the galaxy

Front 31

Population II stars

Back 31

are primarily old low mass stars.
are located in globular clusters.

Front 32

The chemical abundance of population I stars

Back 32

indicates that the material they formed from had been enriched with material from supernovae.

Front 33

The center of our galaxy lies in the direction of the constellation of

Back 33

Sagittarius.

Front 34

The nuclear bulge of our galaxy

Back 34

contains stars primarily associated with the spherical component of our galaxy.

Front 35

Radio maps of the spiral arms of our galaxy

Back 35

map the location of dense neutral hydrogen clouds.

Front 36

Halo stars located in the disk are easy to detect because they

Back 36

move at an angle across the disk.

Front 37

The cosmic microwave background radiation contains small variations in temperature that are about a degree in size. What does the size and distribution of these variations tell us?

Back 37

That the universe is flat.

Front 38

During the first moments of the big bang, nuclear fusion reactions made few heavy elements because

Back 38

no stable nuclei exist with masses of 5 or 8 hydrogen masses.

Front 39

The universe is said to be closed if

Back 39

gravity is strong enough to stop the expansion in a finite time.
the universe is finite.

Front 40

If the universe is closed, then its age will be

Back 40

less than two-thirds of 1/H.

Front 41

The steady state theory was abandoned primarily due to the discovery of

Back 41

the primordial background radiation.

Front 42

Baryonic matter includes

Back 42

protons
neutrons
MACHOs

Front 43

_______________ cause sudden brightening of distant stars by gravitationally lensing the light from those stars. This processes causes the distant stars to grow brighter over a period of a few tens of days.

Back 43

MACHOs

Front 44

Measured ages of globular clusters and a study of the time required for massive stars to build up the present abundance of heavy elements suggests that the universe is

Back 44

at least 13 billion years old.

Front 45

The cosmic background radiation comes from the time in the evolution of the universe

Back 45

when electrons began to recombine with nuclei to form atoms.

Front 46

If the universe is flat and not accelerating

Back 46

the universe's age will be equal two-thirds of 1/H.

Front 47

The flatness problem and horizon problem

Back 47

are solved if there was a sudden inflation of the universe at a very early time.

Front 48

Galaxy seeds around which galaxies, clusters and walls grew may be

Back 48

defects in space-time.

Front 49

The best scientific data and models suggest that the universe is

Back 49

flat, expanding, and accelerating.

Front 50

If a two-dimensional universe has a negative curvature,

Back 50

the universe is infinite.

Front 51

The _______________ proposes that matter was created continuously so that the density of the universe never changes as the universe expands

Back 51

steady state theory

Front 52

The age of the universe can be determined if

Back 52

the Hubble constant and density of the universe can be accurately determined.

Front 53

The flatness problem is that

Back 53

the density of the universe is very close to the critical density.

Front 54

What evidence supports an acceleration in the expansion rate of the universe?

Back 54

The discovery that type Ia supernova in distant galaxies are 25 percent fainter than expected.