Archive for April 2019

Which statement about the first quarter moon is FALSE?

Naim 02:30

Which statement about the first quarter moon is FALSE?



A) It occurs about a week after the new moon
B) It is the half moon of the evening sky
C) From the Earth, it appears 25% sunlit
D) It is highest in the sky at sunset
E) It rises about noon


Answer: C

The last quarter phase of the Moon:

Naim 02:30

The last quarter phase of the Moon:



A) Rises at sunset
B) Sets at sunset
C) Sets at sunrise
D) Rises at sunrise
E) Crosses the meridian at sunrise


Answer: E

If your astrological sign is Aries, the Sun should be in the constellation Aries on your birthday. The dates, according to astrological tradition, during which the Sun is in the constellation Aries are March 21 to April 20th. In which constellation is the Sun actually in, during this time period?

Naim 02:25

If your astrological sign is Aries, the Sun should be in the constellation Aries on your birthday. The dates, according to astrological tradition, during which the Sun is in the constellation Aries are March 21 to April 20th. In which constellation is the Sun actually in, during this time period?



A) Aquarius
B) Aries
C) Taurus
D) Gemini
E) Pisces


Answer: E

Which statement about the length of a day is FALSE?

Naim 02:24

Which statement about the length of a day is FALSE?



A) At the equator, every day is twelve hours long, then twelve hours of the night
B) At the North Pole, the day lasts six months, then six months of night
C) The solar day is four minutes longer than the sidereal one
D) For the United States, June 21st will be the longest day
E) The sidereal day includes both the Earth's rotation and revolution around the Sun


Answer: E

Which physical property of Earth gives rise to the seasons?

Naim 02:23

Which physical property of Earth gives rise to the seasons?



A) Changes in the day-night cycle
B) The variation in its distance from the Sun
C) The precession of its axis
D) The tilt of its rotation axis to the plane of its orbit


Answer: D

Which of the following is NOT true about the astronomical feature is known as the "ecliptic"?

Naim 02:22

Which of the following is NOT true about the astronomical feature is known as the "ecliptic"?



A) It is the plane in which Earth orbits the Sun
B) It is the apparent path through the sky taken by the Sun over the course of the year
C) It is the path taken by the Moon as it orbits Earth
D) It forms a circle on the celestial sphere that is inclined at an angle of 23.5 degrees to the celestial equator
E) It passes through the constellations of the zodiac


Answer: C

From a location in the United States of America, a star is observed to be rising due East. Where will this star be located 6 hours later?

Naim 02:22

From a location in the United States of America, a star is observed to be rising due East. Where will this star be located 6 hours later?



A) Setting due West
B) High in the southern sky
C) High in the northern sky
D) Directly overhead
E) The location of the star cannot be determined from the info given


Answer: B

Which solstice or equinox?

Naim 02:21

Which solstice or equinox?



Answer: The Sun crosses the meridian 23.5 degrees lower in altitude than the celestial equator
The noontime Sun casts the longest shadows
Sunset occurs at its farthest point south of due west for the year
Winter Solstice

Which solstice or equinox?

Naim 02:21

Which solstice or equinox?



Answer: The Sun rises due east today, but will rise slightly north of due east tomorrow
Spring equinox

What are constellations?

Naim 02:19

What are constellations?



A) Groups of stars making an apparent pattern in the celestial sphere
B) Ancient storyboards, useless to modern astronomers
C) Groups of stars gravitationally bound and appearing close together in the sky
D) Apparent grouping of stars and planets visible on a given evening
E) Groups of galaxies gravitational bound and close together in the sky


Answer: A

The angular size of an object depends on which two quantities?

Naim 02:19

The angular size of an object depends on which two quantities?



A) The object's actual size and its distance from us
B) The object's distance from us and its brightness
C) The object's actual size and it's mass
D) The object's brightness and it's mass


Answer: A

In 1 second, light leaving Los Angels reaches approximately as far as

Naim 02:18

In 1 second, light leaving Los Angels reaches approximately as far as



A)Venus, 4500000 km from Earth at closest approach
B) The Moon, 384000 km
C) London, roughly 10000 km
D) The nearest star, about 4 light-years from Earth
E) San Francisco, about 500 km


Answer: B

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is most likely to be located in the halo of our galaxy?

Naim 02:17

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is most likely to be located in the halo of our galaxy? 



A) The diagram shows main-sequence stars of every spectral type except O, along with a few giants and supergiants.
B) The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giants and white dwarfs.
C) The diagram shows main-sequence stars of all the spectral types except O and B, along with a few giants and supergiants.
D) The diagram shows no main-sequence stars at all, but it has numerous supergiants and white dwarfs.


Answer: B

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest?

Naim 02:17

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest? 



A) The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giants and white dwarfs.
B) The diagram shows main-sequence stars of all the spectral types except O and B, along with a few giants and supergiants.
C) The diagram shows main-sequence stars of every spectral type except O, along with a few giants and supergiants.
D) The diagram shows no main-sequence stars at all, but it has numerous supergiants and white dwarfs.


Answer: C

How did astronomers discover the relationship between spectral type and mass for main-sequence stars?

Naim 02:17

How did astronomers discover the relationship between spectral type and mass for main-sequence stars? 



A) by using computer models of hydrogen fusion and stellar structure
B) by measuring stellar radii with very powerful telescopes
C) by comparing stars with the same spectral type but different luminosities
D) by measuring the masses and spectral types of main-sequence stars in binary systems


Answer: D

Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 73 hours the star becomes dimmer for about 2 hours. The most likely explanation is that

Naim 02:13

Careful measurements reveal that a star maintains a steady apparent brightness at most times, except that at precise intervals of 73 hours the star becomes dimmer for about 2 hours. The most likely explanation is that



A) the star is a Cepheid variable.
B) the star is a member of an eclipsing binary star system.
C) the star is periodically ejecting gas into space, every 73 hours.
D) the star is a white dwarf.


Answer: B

Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude?

Naim 02:13

Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude? 



A) Rigel has a higher core temperature than Sirius.
B) Sirius has a higher core temperature than Rigel.
C) Rigel has a higher surface temperature than Sirius.
D) Sirius has a higher surface temperature than Rigel.


Answer: C

Which of the following statements about spectral types of stars is not generally true?

Naim 02:13

Which of the following statements about spectral types of stars is not generally true? 



A) The spectral type of a star can be used to determine its surface temperature.
B) The spectral type of a star can be used to determine its distance.
C) The spectral type of a star can be used to determine its color.
D) The spectral type of a star can be determined by identifying lines in its spectrum.


Answer: B

The star Vega has an absolute magnitude of about 4 and an apparent magnitude of about 0. Based on the definitions of absolute and apparent magnitude, we can conclude that

Naim 02:12

The star Vega has an absolute magnitude of about 4 and an apparent magnitude of about 0. Based on the definitions of absolute and apparent magnitude, we can conclude that 



A) Vega is nearer than 10 parsecs from Earth.
B) Vega has a parallax angle of 1/10 arcsecond.
C) Vega's luminosity is less than that of our Sun.
D) Vega's surface temperature is cooler than the Sun.


Answer: A

Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore

Naim 02:12

Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore



A) both stars have the same luminosity, but the apparent brightness of Star B is twice that of Star A.
B) both stars have the same apparent brightness, but the luminosity of Star B is four times that of Star A.
C) both stars have the same luminosity, but the apparent brightness of Star A is four times that of Star B.
D) both stars have the same luminosity, but the apparent brightness of Star B is four times that of Star A.


Answer: D

All stars are born with the same basic composition, yet stars can look quite different from one another. Which two factors primarily determine the characteristics of a star?

Naim 02:11

All stars are born with the same basic composition, yet stars can look quite different from one another. Which two factors primarily determine the characteristics of a star? 



A) its mass and its stage of life
B) its apparent brightness and its distance
C) its age and its location in the galaxy
D) its mass and its surface temperature
E) its apparent brightness and its luminosity


Answer: A

What do we mean by the main-sequence turnoff point of a star cluster, and what does it tell us?

Naim 02:11

What do we mean by the main-sequence turnoff point of a star cluster, and what does it tell us? 



A) It is the point in a star cluster beyond which main-sequence stars are not found, and it tells us the cluster's distance.
B) It is the spectral type of the hottest main-sequence star in a star cluster, and it tells us the cluster's age.
C) It is the luminosity class of the largest star in a star cluster, and it tells us the cluster's age.
D) It is the mass of the most massive star in the star cluster, and it tells us the cluster's size.


Answer: B

Which of the following statements comparing open and globular star clusters is not true?

Naim 02:11

Which of the following statements comparing open and globular star clusters is not true? 



A) Open clusters are found only in the disk of the galaxy while globular clusters may be found both in the disk and the halo of the galaxy.
B) Stars in open clusters are relatively young while stars in globular clusters are very old.
C) Open and globular clusters each typically contain a few hundred stars.
D) For both open and globular clusters, we can assume that all the stars in a particular cluster are about the same age.


Answer: C

What is a white dwarf?

Naim 02:10

What is a white dwarf? 



A) It is a main-sequence star of spectral type F, which tends to look white in colour.
B) It is the remains of a star that ran out of fuel for nuclear fusion.
C) It is a type of star that produces energy by gravitational contraction.
D) It is a star that follows a period-luminosity relation.


Answer: B

Suppose our Sun were suddenly replaced by a supergiant star. Which of the following would be true?

Naim 02:10

Suppose our Sun were suddenly replaced by a supergiant star. Which of the following would be true? 



A) Earth would be inside the supergiant.
B) The supergiant's surface temperature would be much hotter than the surface temperature of our Sun.
C) Earth would fly off into interstellar space.
D) The supergiant would appear as large as the full Moon in our sky.


Answer: A

What is the common trait of all main-sequence stars?

Naim 02:10

What is the common trait of all main-sequence stars? 




A) They are in the final stage of their lives.
B) They generate energy through hydrogen fusion in their core.
C) They are all spectral type G.
D) They all have approximately the same mass.


Answer: B

How is the lifetime of a star related to its mass?

Naim 02:09

How is the lifetime of a star related to its mass? 



A) More massive stars live slightly shorter lives than less massive stars.
B) More massive stars live much longer lives than less massive stars.
C) More massive stars live much shorter lives than less massive stars.
D) More massive stars live slightly longer lives than less massive stars.


Answer: C

On an H-R diagram, stellar masses

Naim 02:08

On an H-R diagram, stellar masses



A) can be determined for main-sequence stars but not for other types of stars.
B) are greatest in the lower left and least in the upper right.
C) decrease from upper left to lower right.
D) are impossible to determine.


Answer: A

On an H-R diagram, stellar masses

Naim 02:08

On an H-R diagram, stellar masses 



A) can be determined for main-sequence stars but not for other types of stars.
B) are greatest in the lower left and least in the upper right.
C) decrease from upper left to lower right.
D) are impossible to determine.


Answer: A

On an H-R diagram, stellar radii

Naim 02:08

On an H-R diagram, stellar radii 



A) are greatest in the lower left and least in the upper right.
B) decrease from left to right.
C) are impossible to determine.
D) increase diagonally from the lower left to the upper right.


Answer: D

Astronomers can measure a star's mass in only certain cases. Which one of the following cases might allow astronomers to measure a star's mass?

Naim 02:07

Astronomers can measure a star's mass in only certain cases. Which one of the following cases might allow astronomers to measure a star's mass? 



A) The star is a member of a binary star system.
B) The star is of spectral type G.
C) The star is of spectral type A.
D) We know the star's luminosity and distance.


Answer: A

Ten parsecs is about

Naim 02:07

Ten parsecs is about



A) 150 million kilometres.
B) 10,000 seconds.
C) 10 parallax seconds of angle.
D) 32.6 light-years.


Answer: D

Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do?

Naim 02:06

Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do? 



A) Determine both the star's distance and luminosity from its apparent brightness.
B) Determine the distance to the star from its apparent brightness.
C) Calculate the star's luminosity if we know its distance, or calculate its distance if we know its luminosity.
D) Calculate the star's surface temperature if we know either its luminosity or its distance.


Answer: C

According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples?

Naim 02:06

According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples? 



A) Its apparent brightness will increase by a factor of 9.
B) Its apparent brightness will decrease by a factor of 9.
C) Its apparent brightness will increase by a factor of 3.
D) Its apparent brightness will decrease by a factor of 3.


Answer: B

In order to understand star clusters, we need to be able to estimate their ages. What technique do scientists use for this?

Naim 02:05

In order to understand star clusters, we need to be able to estimate their ages. What technique do scientists use for this? 



A) radioisotope dating
B) counting the planets that have formed around the largest stars
C) finding the main-sequence turnoff point of the stars
D) calculating orbital parameters using Kepler's Laws
E) measuring its parallax


Answer: C

Cluster ages can be determined from

Naim 02:05

Cluster ages can be determined from 



A) main sequence fitting.
B) main sequence turnoff.
C) pulsating variable stars.
D) spectroscopic binaries.
E) visual binaries.


Answer: B

Which of the following statements about a globular cluster is true?

Naim 02:05

Which of the following statements about a globular cluster is true? 



A) All stars in the cluster are approximately at the same stage in evolution.
B) Most of the stars in the cluster are younger than 10 billion years old.
C) Most stars in the cluster are yellow or reddish in colour.
D) All stars in the cluster have approximately the same mass.
E) There is an approximately equal number of all types of stars in the cluster.


Answer: C

Which of the following statements about an open cluster is true?

Naim 02:04

Which of the following statements about an open cluster is true? 



A) All stars in the cluster are approximately the same colour.
B) All stars in the cluster are approximately the same age.
C) All stars in the cluster have approximately the same mass.
D) All stars in the cluster will evolve similarly.
E) There is an approximately equal number of all types of stars in the cluster.


Answer: B

Why are Cepheid variables so important for measuring distances in astronomy?

Naim 02:04

Why are Cepheid variables so important for measuring distances in astronomy? 



A) They all have the same luminosity.
B) They all have the same period.
C) Their luminosity can be inferred from their period.
D) They are close enough to have a detectable parallax.
E) They are circumpolar like Polaris, the North Star.


Answer: C

Which of the following is true about low-mass stars compared to high-mass stars?

Naim 02:04

Which of the following is true about low-mass stars compared to high-mass stars? 



A) Low-mass stars are cooler and less luminous than high-mass stars.
B) Low-mass stars are hotter and more luminous than high-mass stars.
C) Low-mass stars are cooler but more luminous than high-mass stars.
D) Low-mass stars are hotter but less luminous than high-mass stars.
E) Low-mass stars have the same temperature and luminosity as high-mass stars.


Answer: A

On the main sequence, stars obtain their energy

Naim 02:00

On the main sequence, stars obtain their energy 



A) from chemical reactions.
B) from gravitational contraction.
C) by converting hydrogen to helium.
D) by converting helium to carbon, nitrogen, and oxygen.
E) from nuclear fission.


Answer: C

You observe a star in the disk of the Milky Way, and you want to plot the star on an H-R diagram. You will need to determine all of the following, except the

Naim 01:55

You observe a star in the disk of the Milky Way, and you want to plot the star on an H-R diagram. You will need to determine all of the following, except the 



A) spectral type of the star.
B) distance to the star.
C) apparent brightness of the star in our sky.
D) rotation rate of the star.


Answer: D

Which of the following best describes the axes of a Hertzsprung-Russell (H-R) diagram?

Naim 01:52

Which of the following best describes the axes of a Hertzsprung-Russell (H-R) diagram? 



A) surface temperature on the horizontal axis and luminosity on the vertical axis
B) mass on the horizontal axis and luminosity on the vertical axis
C) surface temperature on the horizontal axis and radius on the vertical axis
D) mass on the horizontal axis and stellar age on the vertical axis
E) interior temperature on the horizontal axis and mass on the vertical axis


Answer: A

Suppose you see two main-sequence stars of the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude? (Neglect any effects that might be caused by interstellar dust and gas.)

Naim 01:50

Suppose you see two main-sequence stars of the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude? (Neglect any effects that might be caused by interstellar dust and gas.) 



A) Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other.
B) The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2.
C) Star 1 is 100 times more distant than Star 2.
D) Star 1 is 100 times nearer than Star 2.
E) Star 1 is 10 times more distant than Star 2.


Answer: E

Which of the following statements about spectral types of stars is true?

Naim 01:48

Which of the following statements about spectral types of stars is true? 



A) The spectral type of a star can be used to determine its surface temperature.
B) The spectral type of a star can be used to determine its color.
C) A star with spectral type A is cooler than a star with spectral type B.
D) A star with spectral type F2 is hotter than a star with spectral type F3.
E) All of the above are true.


Answer: E

Why is the spectral sequence of stars not alphabetical?

Naim 01:48

Why is the spectral sequence of stars not alphabetical? 



A) The letters refer to the initials of the original discovery.
B) The original alphabetical labelling did not correspond to surface temperature and thus had to be reordered.
C) They were chosen to fit a mnemonic.
D) Because there is still uncertainty over what generates the energy in stellar cores.
E) Because it refers to stellar masses and these were difficult to measure accurately.


Answer: B

Which of the following statements about apparent and absolute magnitudes is true?

Naim 01:47

Which of the following statements about apparent and absolute magnitudes is true? 



A) The magnitude system that we use now is based on a system used by the ancient Greeks over 2,000 years ago that classified stars by how bright they appeared.
B) A star with apparent magnitude 1 is brighter than one with apparent magnitude 2.
C) The absolute magnitude of a star is another measure of its luminosity.
D) A star's absolute magnitude is the apparent magnitude it would have if it were at a distance of 10 parsecs from Earth.
E) All of the above are true.


Answer: E

Why do astronomers often measure the visible-light apparent brightness instead of the total apparent brightness of a star?

Naim 01:44

Why do astronomers often measure the visible-light apparent brightness instead of the total apparent brightness of a star? 



A) All stars put out most of their light in the visible range of the spectrum.
B) In order to measure the total apparent brightness of a star, you must measure its brightness in all wavelengths, and this is difficult to do. The only wavelengths you can measure from the surface of Earth are visible and radio wavelengths.
C) Most stars do not put out the light in other ranges of the spectrum.
D) They are identical for most stars.
E) Astronomers are lazy.


Answer: B

If the distance between us and a star is doubled, with everything else remaining the same, the luminosity

Naim 01:42

If the distance between us and a star is doubled, with everything else remaining the same, the luminosity 



A) is decreased by a factor of four, and the apparent brightness is decreased by a factor of four.
B) is decreased by a factor of two, and the apparent brightness is decreased by a factor of two.
C) remains the same, but the apparent brightness is decreased by a factor of two.
D) remains the same, but the apparent brightness is decreased by a factor of four.
E) is decreased by a factor of four, but the apparent brightness remains the same.


Answer: d

A star's luminosity is the

Naim 01:41

A star's luminosity is the 



A) apparent brightness of the star in our sky.
B) surface temperature of the star.
C) lifetime of the star.
D) total amount of light that the star will radiate over its entire lifetime.
E) total amount of light that the star radiates each second.


Answer: E

Approximately, what basic composition are all stars born with?

Naim 01:39

Approximately, what basic composition are all stars born with? 



A) half hydrogen, half helium, no more than 2 percent heavier elements
B) three-quarters hydrogen, one-quarter helium, no more than 2 percent heavier elements
C) 90 percent hydrogen, 10 percent helium, no more than 1 percent heavier elements
D) one-quarter hydrogen, three-quarters helium, no more than 2 percent heavier elements
E) 98 percent hydrogen, 2 percent helium


Answer: B

In the formation of our Galaxy

Naim 01:25

In the formation of our Galaxy



a) the spiral arms formed first.
b) the globular clusters formed first.
c) the disk component started out thin and grew.
d) spiral density waves formed first.
e) the bar in the bulge formed first.


Answer: b) the globular clusters formed first.

The period-luminosity relationship is a crucial component of

Naim 01:23

The period-luminosity relationship is a crucial component of



a) measuring distances with Cepheid variable stars.
b) identifying the mass of the Galaxy's central black hole.
c) determining the masses of stars in an eclipsing binary system.
d) using spectroscopic parallax to measure distances to stars.


Answer: a) measuring distances with Cepheid variable stars

A nova involves

Naim 01:22

A nova involves



a) mass transfer onto a white dwarf in a binary star system.
b) repeated helium fusion flashes in red giants.
c) rapid collapse of a protostar into a massive O star.
d) the explosion of a low-mass star.
e) the birth of a massive star in a new cluster


Answer: a) mass transfer onto a white dwarf in a binary star system.

The helium flash occurs

Naim 01:20

The helium flash occurs



a) when T-Tauri bipolar jets shoot out.
b) in the middle of the main sequence stage.
c) in the red giant stage.
d) during the formation of a neutron star.
e) in the planetary nebula stage.


Answer: c) in the red giant stage.

21-centimeter radiation is important because?

Naim 01:19

21-centimeter radiation is important because?



a) its radio waves pass unaffected through clouds of interstellar dust.
b) it arises from cool helium gas present throughout space.
c) it can be detected with optical telescopes.
d) it is produced by protostars.
e) it reveals the structure of new stars.


Answer: a) its radio waves pass unaffected through clouds of interstellar dust

Stellar parallax is used to measure the

Naim 01:19

Stellar parallax is used to measure the



a) sizes of stars.
b) distances of stars.
c) temperatures of stars.
d) radial velocity of stars.
e) brightness of stars


Answer: b) distances of stars.

What two observations allow us to estimate the Galaxy's mass?

Naim 01:18

What two observations allow us to estimate the Galaxy's mass?



a) the Sun's mass and velocity in orbit around the galactic center
b) the rotation of the bulge and disk components
c) the Sun's age and age of the globular cluster stars
d) the motion of spiral arms and the mass of the central black hole
e) the orbital period and distance from the galactic center of objects near the edge of the Galaxy


Answer: e) the orbital period and distance from the galactic center of objects near the edge of the Galaxy

Compared to stars like the Sun in the disk of the Milky Way, stars that populate the extended spheroidal halo of the galaxy were born

Naim 01:00

Compared to stars like the Sun in the disk of the Milky Way, stars that populate the extended spheroidal halo of the galaxy were born



a) earlier, so have had time to accumulate more heavy elements
b) later, so have used up their heavy elements
c) earlier, from more nearly primordial material, so have fewer elements
d) later, so have accumulated more heavy elements from previous generations of stars


Answer: c) earlier, from more nearly primordial material, so have fewer elements

The primary reason that massive O-type stars are not found in the galactic halo is that they are

Naim 00:59

The primary reason that massive O-type stars are not found in the galactic halo is that they are



a) too massive to be kicked into the halo from the disk
b) so massive that they settle into the inner disk
c) too short-lived to have persisted from halo formation until today
d) closer to us in the disk than in the extended halo


Answer: c) too short-lived to have persisted from halo formation until today

Kepler's Third Law does NOT apply to the motion of

Naim 00:58

Kepler's Third Law does NOT apply to the motion of



a) a satellite orbiting Earth.
b) a comet around the Sun.
c) one star about another in a binary system.
d) one galaxy about another.
e) Actually, it applies to all of the above.


Answer: e) Actually, it applies to all of the above.

Our Sun is located in the Milky Way Galaxy

Naim 00:57

Our Sun is located in the Milky Way Galaxy



a) about 30 Kpc from the center in the halo.
b) 30,000 light-years from the center in a globular cluster.
c) at the outer edge of the galactic disk, in the plane.
d) about halfway from the center, in the spiral arms.
e) in the bulge, near the Orion arm


Answer: d) about halfway from the center, in the spiral arms

The location of the galactic centre was identified using

Naim 00:57

The location of the galactic centre was identified using



a) supernova remnants.
b) white dwarf stars in the spiral arms.
c) giant variable stars in globular clusters.
d) bright O and B stars in open clusters.
e) X-ray sources


Answer: c) giant variable stars in globular clusters.

A nova involves

Naim 00:56

A nova involves



a) mass transfer onto a white dwarf in a binary star system.
b) repeated helium fusion flashes in red giants.
c) rapid collapse of a protostar into a massive O star.
d) the explosion of a low-mass star.
e) the birth of a massive star in a new cluster.


Answer: a) mass transfer onto a white dwarf in a binary star system.

A white dwarf can explode when

Naim 00:56

A white dwarf can explode when



a) its mass exceeds the Chandrasekhar limit.
b) its electron degeneracy increases enormously.
c) fusion reactions increase in it's core.
d) iron in its core collapses.
e) the planetary nebula stage ends.


Answer: a) its mass exceeds the Chandrasekhar limit.

A key feature of globular clusters is that they have

Naim 00:55

A key feature of globular clusters is that they have



a ) very few cool stars.
b) the oldest stars in our Galaxy.
c) lots of massive main sequence stars.
d) stars with very different ages.
e) high concentrations of metals.


Answer: b) the oldest stars in our Galaxy.

Astronomers determine the age of star clusters by observing

Naim 00:54

Astronomers determine the age of star clusters by observing



a) the number of main sequence stars.
b) the ratio of giants to supergiants.
c) the luminosity of stars at the turnoff point.
d) the number of white dwarfs.
e) supernova explosions.


Answer: c) the luminosity of stars at the turnoff point.

Stars like our Sun will end their lives as

Naim 00:52

Stars like our Sun will end their lives as



a) red giants.
b) pulsars.
c) black holes.
d) white dwarfs.
e) red dwarfs.


Answer: d) white dwarfs.

During formation, the Sun evolved toward the main sequence as shown in the figure. The Sun will evolve away from the main sequence when

Naim 00:52

During formation, the Sun evolved toward the main sequence as shown in the figure. The Sun will evolve away from the main sequence when



a) its core begins fusing iron.
b) its supply of hydrogen is used up.
c) the carbon core detonates, and it explodes as a Type I supernova.
d) helium builds up in the core, while the hydrogen-burning shell expands.
e) the core loses all of its neutrinos, so all fusion ceases


Answer: d) helium builds up in the core, while the hydrogen-burning shell expands.

A star like our Sun will spend most of its "shining" lifetime

Naim 00:52

A star like our Sun will spend most of its "shining" lifetime



a) as a protostar.
b) as a red giant.
c) as a main-sequence star.
d) as a white dwarf.
e) evolving from type O to type M.


Answer: c) as a main-sequence star.

What is a T-Tauri star?

Naim 00:52

What is a T-Tauri star? 



a) a collapsing cloud of gas about to become a protostar
b) a dying star
c) a cool main sequence star
d) a star releasing a planetary nebula
e) a protostar about to become a star


Answer: e) a protostar about to become a star

The reddish colour of emission nebulae indicates that

Naim 00:51

The reddish colour of emission nebulae indicates that



a) gas and dust is moving away from Earth.
b) hydrogen gas is present.
c) dying stars have recently exploded.
d) cool red stars are hidden inside.
e) dust is present.


Answer: b) hydrogen gas is present.

Some regions of the Milky Way's disk appear dark because

Naim 00:51

Some regions of the Milky Way's disk appear dark because



a) there are no stars there.
b) stars in that direction are obscured by interstellar gas.
c) stars in that direction are obscured by interstellar dust.
d) numerous black holes capture all the starlight behind them


Answer: c) stars in that direction are obscured by interstellar dust.

Objects more massive than our Sun form into stars

Naim 00:50

Objects more massive than our Sun form into stars



a) much slower, over billions of years.
b) in about the same time.
c) much faster, over tens of thousands of years.
d) not at all - they are unstable


Answer: c) much faster, over tens of thousands of years.

Stars are formed from cold interstellar gas clouds made up of

Naim 00:50

Stars are formed from cold interstellar gas clouds made up of



a) atomic gas of mostly hydrogen, oxygen, carbon, and nitrogen.
b) molecular hydrogen gas and dust grains.
c) some hydrogen gas, comets, and asteroids.
d) stars are formed from very HOT gas


Answer: b) molecular hydrogen gas and dust grains.

Astronomers use the term nebula to refer to

Naim 00:49

Astronomers use the term nebula to refer to



a) outer envelopes of dying stars that drift gently into space.
b) remnants of stars that die by supernova.
c) clouds of gas and dust in interstellar space.
d) distant galaxies seen beyond our Milky Way.
e) All of the above are correct.


Answer: e) All of the above are correct.

Interstellar gas is composed primarily of

Naim 00:49

Interstellar gas is composed primarily of



a) 90% hydrogen, 9% helium, and 1% heavier elements.
b) molecules including water and CO2.
c) 50% hydrogen, 50% helium.
d) hydrogen, oxygen, and nitrogen.
e) 99% hydrogen, and 1% heavier elements.


Answer: a) 90% hydrogen, 9% helium, and 1% heavier elements.

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