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Quiz - Chapter 11 & 12

True/False
Indicate whether the statement is true or false. (1-Point Each)
 

 1. 

The rotation curve of the galaxy provides evidence for the existence of the galactic corona which extends beyond the halo of the galaxy.
 

 2. 

The density wave theory explains spurs and branches along the spiral arms.
 

 3. 

Giant molecular cloud complexes are located in spiral arms.
 

 4. 

We would not expect to find a 5 solar mass neutron star because it would be a black hole.
 

 5. 

Because of the rapid rotation of the outer portion of our galaxy suggest that it is more massive than we previously thought.
 

 6. 

Globular clusters are groups of 100,000 to 1,000,000 population II stars firmly bound by gravity.
 

 7. 

The event horizon or Schwarzschild radius of a black hole is the radius from the black hole at which the escape velocity is equal to the speed of light.
 

 8. 

The sun and stars are supported by gas pressure, neutron stars are supported by internuclear forces.
 

 9. 

Theory predicts that neutron stars may not exceed 3 solar masses.
 

 10. 

The disk of the galaxy is older than the halo.
 

 11. 

Pulsars could not be pulsating stars because the pulses are too short.
 

 12. 

Spiral tracers tend to be old, luminous stars.
 

 13. 

Old stars are poor in heavy atoms because there were very few previous generations of stars before the old stars formed.
 

 14. 

The rapid rotation in the outer disk suggests that our galaxy is more massive than previously thought.
 

 15. 

The center of our galaxy is believed to be occupied by the radio source known as Sgr A* or Sagittarius A*.
 

 16. 

We expect neutron stars to spin rapidly because they conserve angular momentum.
 

 17. 

Shapley found the distance to the center of the galaxy by studying the distance to open clusters.
 

 18. 

The center of our galaxy shows signs of past eruptions.
 

 19. 

Many pulsars have periods that are gradually increasing as the spinning neutron stars lose energy.
 

 20. 

Neutron stars have densities roughly the same as that of the atomic nucleus.
 

 21. 

The disk of the Milky Way is approximately 20,000 ly in diameter.
 

 22. 

The event horizon marks the boundary within which the density is roughly the same as that of the atomic nucleus.
 

 23. 

If the accretion disk around a black hole emits X rays outside the event horizon, the X rays can escape.
 

 24. 

The center of our galaxy is located in the direction of the constellation of Orion.
 

 25. 

The halo of the galaxy contains population I stars, open clusters, and gas clouds.
 

 26. 

The ‘pizza theory’ is used to briefly explain the hailo of the Milky Way galaxy.
 

Multiple Choice
Identify the choice that best completes the statement or answers the question. (3-Points Each)
 

 27. 

The nuclear bulge of our galaxy
a.
contains stars that are primarily population I stars.
b.
contains relatively large amounts of gas and dust.
c.
contains stars primarily associated with the spherical component of our galaxy.
d.
contains stars primarily associated with the disk component of our galaxy.
e.
a, b and d
 

 28. 

Which of the following is not a characteristic of the stars of the disk component of our galaxy?
a.
circular orbits
b.
randomly inclined orbits
c.
higher metal abundance
d.
young stars
e.
star formation regions
 

 29. 

Our galaxy is suspected to be surrounded by a galactic corona because the disk of the galaxy
a.
rotates faster than expected in its outer region.
b.
rotates more slowly than expected in its outer region.
c.
rotates faster than expected in its inner region.
d.
rotates more slowly than expected in its inner region.
e.
is much flatter than expected.
 

 30. 

A pulsar requires that a neutron star

I.
rotate rapidly.
II.
have a radius of at least 10 km.
III.
have a strong magnetic field.
IV.
rotate on an axis that is different from the axis of the magnetic field.
a.
I & III
b.
I & IV
c.
II, III, & IV
d.
I, III, & IV
e.
I, II, III, & IV
 

 31. 

The density of a _________ is greater than the density of a _________.
a.
white dwarf neutron star
b.
neutron star black hole
c.
pulsar neutron star
d.
pulsar white dwarf
e.
white dwarf black hole
 

 32. 

A Type II Cepheid has been located in a distant globular cluster with a period of 10 days, what is the star's absolute magnitude?

mc032-1.jpg
a.
-1
b.
0
c.
-4
d.
-6
e.
The absolute magnitude of a Cepheid
variable cannot be determined unless
its distance is known.
 

 33. 

Radio maps of our galaxy show spiral arms because
a.
the arms have larger Doppler shifts.
b.
the gas in the spiral arms is very hot.
c.
the dust in spiral arms is denser.
d.
the gas in spiral arms is denser.
e.
the stars in the spiral arms emit most of their energy at radio wavelengths.
 

 34. 

The event horizon
a.
is believed to be a singularity.
b.
is a crystalline layer.
c.
has a radius equal to the Schwarzschild radius.
d.
marks the inner boundary of a planetary nebula.
e.
is located at the point where synchrotron radiation is created around a pulsar.
 

 35. 

The orbits of population I stars

I.
are confined to disk of the galaxy.
II.
are very elliptical.
III.
are nearly circular.
IV.
are randomly inclined to the disk of the galaxy.
a.
I
b.
IV
c.
I & IV
d.
II & IV
e.
I & III
 

 36. 

If the spiral density wave were the only thing producing spiral arms, it would be expected that
a.
all spiral arms would be dust free.
b.
all galaxies would have only two smooth spiral arms.
c.
the Milky Way would be more massive than observed.
d.
the Milky Way wouldn't have any spiral arms.
e.
the halo component of the Milky way would show spiral arms as well.
 

 37. 

The traditional theory states that the galaxy formed
a.
as a large spherical cloud of gas that was rotating very slowly.
b.
from a large cloud of material that broke off a larger galaxy.
c.
from material that had been ejected in the violent explosion of a dying galaxy.
d.
as a result of mergers between several smaller groups of gas, dust, and stars.
e.
as two massive galaxies collided.
 

 38. 

A group of 10 to 100 stars that formed at the same time but are so widely scattered in space their mutual gravity cannot hold them together is called
a.
a globular cluster.
b.
an open cluster.
c.
an association.
d.
a spherical component
e.
an accretion disk.
 

 39. 

Radio maps of the spiral arms of our galaxy
a.
reveal that our galaxy is a grand design spiral.
b.
map the location of Hot O and B stars by the radio radiation they emit.
c.
reveal that the spiral arms are winding up and growing closer together.
d.
reveal that the sun is currently located in the center of a spiral arm.
e.
map the location of dense neutral hydrogen clouds.
 

 40. 

The density of a neutron star is
a.
about the same as that of a white dwarf.
b.
about the same as that of the sun.
c.
about the same as an atomic nucleus.
d.
about the same as a water molecule.
e.
smaller than expected because the magnetic field is so strong.
 

 41. 

The first pulsar was discovered by _________ in November of 1967.
a.
Jocelyn Bell
b.
Isaac Newton
c.
Albert Einstein
d.
Walter Baade
e.
Edwin Hubble
 

 42. 

The energy source at the center of our galaxy
a.
is not visible at optical wavelengths.
b.
produces x rays.
c.
must be less than 10 AU in diameter.
d.
all of the above
e.
none of the above.
 

 43. 

The search for black holes involves searching for
a.
single stars that emit large amounts of x-rays.
b.
x-ray binaries where the compact companion has a mass in excess of 3 Mmc043-1.jpg.
c.
large spherical regions from which no light is detected.
d.
pulsars with periods less than one millisecond.
e.
pulsars that are orbited by planets.
 

 44. 

None of the pulsars emit pulses of visible light because
a.
pulsars are to hot to emit visible light.
b.
pulsars contain black holes that won't let visible light escape.
c.
the gravitational field of a pulsar is so great that the visible light emitted is red shifted.
d.
pulsars are too far away for the visible light to be bright enough to be detected at Earth.
e.
A few pulsars do emit visible light pulses.
 

 45. 

Who first calibrated the Cepheid variable stars for use in determining distance?
a.
Henrietta Leavitt
b.
Edwin Hubble
c.
John Glenn
d.
Carl Sagan
e.
Harlow Shapley
 

 46. 

The chemical abundance of population I stars
a.
indicates that they were formed before the population II stars.
b.
indicates that the material they formed from had been enriched with material from supernovae.
c.
indicates that they contain very few heavy metals compared to halo stars.
d.
depends on the temperature of the star.
e.
depends on the mass of the star.
 

 47. 

Nucleosynthesis
a.
is the process by which energy is produced at the center of the galaxy.
b.
is the process by which hydrogen and helium are converted into heavier elements.
c.
describes the structure of a globular cluster.
d.
describes how the magnetic field of the galaxy traps cosmic rays.
e.
describes the method by which neutral hydrogen produces 21 cm radiation.
 

 48. 

The center of our galaxy lies in the direction of the constellation of
a.
Ursa Minor.
b.
Ursa Major.
c.
Sagittarius.
d.
Orion.
e.
Monoceros.
 

 49. 

Why are Cepheid variable stars important in our study of the Milky Way galaxy?
a.
It allows us to determine the center of our galaxy.
b.
It helps us understand the size of our galaxy.
c.
It helps us understand the shape of our galaxy.
d.
All of the above
e.
None of the above
 

 50. 

The first stars to form in our galaxy
a.
had circular orbits.
b.
had highly elliptical orbits.
c.
were population I stars.
d.
all had orbits in the same plane.
e.
formed the galactic clusters we see today.
 

 51. 

An isolated black hole in space would be difficult to detect because
a.
there would be no light source nearby.
b.
it would not be rotating rapidly.
c.
it would be stationary.
d.
very little matter would be falling into it.
e.
there would be very few stars behind it whose light it could block out.
 

 52. 

Population II stars

I.
are primarily found in the disk of the galaxy.
II.
contain more heavy metals than population I stars.
III.
are primarily old low mass stars.
IV.
are located in globular clusters.
a.
III & IV
b.
I & II
c.
II
d.
IV
e.
I, II, & III
 

 53. 

Although neutron stars are very hot, they are not easy to locate because
a.
light does not escape from their event horizon.
b.
most lie beyond dense dust clouds.
c.
solid neutron material cannot radiate photons.
d.
they are only found in other galaxies.
e.
they have small surface areas.
 

 54. 

Younger stars have more heavy elements because
a.
old stars destroy heavy elements as they age.
b.
young stars burn their nuclear fuels faster.
c.
the heavy elements were made in previous generations of stars.
d.
heavy elements haven't had time to settle to the core of these younger stars.
e.
all of these
 

 55. 

_________ first noticed that for Cepheid variable stars, there was a direct relation between the luminosity and the period of the variation in their brightness.
a.
Henrietta Leavitt
b.
Edwin Hubble
c.
John Glenn
d.
Carl Sagan
e.
Annie Cannon
 

 56. 

Good spiral tracers are all

I.
very old.
II.
very young.
III.
very luminous.
IV.
moving with large radial velocities.
a.
I & III
b.
I & IV
c.
II & III
d.
II & IV
e.
I, III, & IV
 

 57. 

The bottom-up theory states that the galaxy formed
a.
as material accreted around a massive black hole currently at the center of our galaxy.
b.
from a large cloud of material that broke off a larger galaxy.
c.
from material that had been ejected in the violent explosion of a dying galaxy.
d.
as a result of mergers between several smaller groups of gas, dust, and stars.
e.
as two massive galaxies collided.
 

 58. 

Sgr A* is believed to be the center of the Milky Way galaxy because

I. It lies in the general direction of the center of the galaxy based on observations of globular clusters.
II. It is located near the galactic corona.
III. It is easily visible with optical telescopes and has the appearance of a massive black hole.
IV. It does not move with respect to the rest of the galaxy.
a.
I & II
b.
II & III
c.
I & IV
d.
II & IV
e.
I, III, & IV
 

 59. 

The age of the Milky Way galaxy has been estimated to be at least 15 billion years based on
a.
observations of globular clusters.
b.
observations of open clusters.
c.
21-cm radiation from H I regions.
d.
the rotation curve of the galaxy.
e.
the energy produced by Sagittarius A*.
 

 60. 

As material flows into a black hole
a.
the material will experience time dilation.
b.
the material will become hotter.
c.
the material will produce an absorption spectrum.
d.
the material will appear to us to fall into the black hole very rapidly.
e.
a and b
 



 
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