Deck 6: The Family of Stars

Question 1

How can we tell that some stars are relatively close to us in the sky?

A) Some stars are occasionally eclipsed by the Moon, so they must be nearby.
B) Some stars vary in brightness caused by sunspots that we can see because they are so close.
C) Some stars appear to be extremely bright and must therefore be very close to us.
D) Some stars appear to move periodically back and forth against the background stars because of the Earth's movement around the Sun.

Answer 1

Some stars appear to move periodically back and forth against the background stars because of the Earth's movement around the Sun.

Question 2

Star A has twice the intrinsic visual luminosity as Star B, and Star A is twice as far from Earth as Star B. How will the flux received from each star compare as recorded by a certain telescope on Earth?

A) The flux from Star A will equal the flux from Star B.
B) The flux from Star A will be twice the flux from Star B.
C) The flux from Star A will be half the flux from Star B.
D) The flux from Star A will be one-quarter the flux from Star B.

Answer 2

The flux from Star A will be half the flux from Star B.

Question 3

If you compare two stars, which one will always have the greater luminosity?

A) The one with the larger radius will always have the greater luminosity.
B) The one with the higher surface temperature will always have the greater luminosity.
C) The one with the smaller absolute magnitude will always have the greater luminosity.
D) The one with the largest distance will always have the greater luminosity.

Answer 3

The one with the smaller absolute magnitude will always have the greater luminosity.

Question 4

What is the most accurate way to determine the surface temperature of a star?

A) Study the pattern of absorption lines from various atoms.
B) Study the relative intensities of light measured through different photometric filters.
C) Study the peak wavelength of the star's continuum blackbody spectrum.
D) Study the pattern of emission lines on the star's spectrum.

Question 5

What aspect of a star is a measure of the total energy radiated by the star in one second?

A) apparent visual magnitude
B) luminosity class
C) spectral type
D) luminosity

Question 6

What is absolute visual magnitude?

A) the luminosity of a star observed from Earth
B) the luminosity of a star observed from a distance of 1000 parsecs
C) the apparent magnitude of a star observed from a distance of 10 parsecs
D) the apparent magnitude of a star observed from Earth

Question 7

Absolute magnitude is defined as the apparent magnitude that a star would have if observed at a distance of 33 light-years. Consider a star at a distance of 350 light-years that has an apparent magnitude of +5. What would its absolute magnitude be?

A) It would be less than +5.
B) It would be exactly +5.
C) It would be greater than +5.
D) More information on the star's luminosity would be required to answer this question.

Question 8

What is the spectral sequence in order of decreasing temperature?

A) OBAFGKM
B) OBAGFKM
C) BAGFKMO
D) ABFGKMO

Question 9

The parsec is defined so that a star at a distance of 1 parsec has a parallax of one arcsecond. If a star has a parallax of 0.05 seconds of arc, what is its distance?

A) 2 parsecs
B) 5 parsecs
C) 20 parsecs
D) 50 parsecs

Question 10

What would make parallax easier to measure?

A) the Earth's orbit being larger
B) the stars being farther away
C) the Earth moving faster along its orbit
D) stars moving faster in their orbits

Question 11

Imagine you tried to measure the parallax of distant stars from the surface of Mars. How would your results compare to what you would find from Earth?

A) Each star's parallax would be smaller because Mars has a smaller orbital speed.
B) Each star's parallax would be smaller because Mars is farther from the Sun.
C) Each star's parallax would be larger because Mars is closer to the stars.
D) Each star's parallax would be larger because Mars has a larger orbit.

Question 12

Which of the following can the strength of spectral lines tell you about a star?

A) the radius
B) the distance
C) the temperature
D) the visual magnitude

Question 13

If two stars are emitting the same amount of light, how will the star that is farther away appear?

A) brighter
B) dimmer
C) redder
D) bluer

Question 14

The nearest star, Proxima Centauri, is about four light-years away and has a luminosity about 0.001 times that of the Sun. If Proxima Centauri were at a distance of one light-year instead of four, how much brighter would it appear in the sky?

A) twice as bright
B) four times as bright
C) 16 times as bright
D) 4000 times as bright

Question 15

You observe weak hydrogen Balmer lines in a star's spectrum. What can you conclude about the star's temperature?

A) The star has a low temperature, less than about 6000 K.
B) The star has an intermediate temperature, about 10 000 K.
C) The star has a high temperature, greater than about 20 000 K.
D) The star may have a low or high temperature.

Question 16

Which stars have a large positive absolute magnitude?

A) stars of high luminosity
B) stars of low luminosity
C) nearby stars
D) distant stars

Question 17

The parsec is defined so that a star at a distance of 1 parsec has a parallax of one arcsecond. If a star is located at a distance of 40 parsecs, what is its parallax?

A) 0.25 arcseconds
B) 0.025 arcseconds
C) 0.04 arcseconds
D) 0.05 arcseconds

Question 18

The parsec is defined so that a star at a distance of 1 parsec has a parallax of one arcsecond. If a star has a parallax of 0.02 seconds of arc, what is its distance?

A) 2 parsecs
B) 5 parsecs
C) 20 parsecs
D) 50 parsecs

Question 19

How does a star's surface temperature determine the appearance of its spectrum?

A) Surface temperature affects which elements are solid, liquid, or gaseous.
B) Surface temperature determines the luminosity of the star.
C) Surface temperature affects which elements can escape from the surface of the star.
D) Surface temperature determines the velocity of collision rates of atoms and ions.

Question 20

The parsec is defined so that a star at a distance of 1 parsec has a parallax of one arcsecond. If a star is located at a distance of 10 parsecs, what is its parallax?

A) 0.1 arcseconds
B) 0.01 arcseconds
C) 1 arcsecond
D) 10 arcseconds

Question 21

Which star in the table has the highest surface temperature?

A) δ Cen
B) HR 4758
C) HD 39801
D) 9 CMa

Question 22

Which of the following can we use to determine the surface temperature of a star?

A) determining if the star has a companion star
B) studying its line absorption spectrum
C) measuring the star's distance
D) measuring the star's parallax

Question 23

When compared to stars near the middle of the diagram, how are stars in the upper right part of the Hertzsprung-Russell diagram different?

A) They are always cooler.
B) They are always larger.
C) They are always smaller.
D) They are always more massive.

Question 24

In a Hertzsprung-Russell diagram, where are 90 percent of all the stars found?

A) in the giant region
B) in the supergiant region
C) on the dwarf sequence
D) on the main sequence

Question 25

The table lists the spectral types for each of four stars. Which star in this table would have the highest surface temperature?

A) α For
B) ο Cet
C) γ Tri
D) ξ Per

Question 26

Use the Hertzsprung-Russell diagram to answer the following question: Which star in the diagram has the highest surface temperature?

A) Alnilam
B) Antares
C) Arcturus
D) Sirius B

Question 27

Which star in the table is the closest to Earth?

A) δ Cen
B) HR 4758
C) HD 39801
D) 9 CMa

Question 28

Sirius A and B are two stars at the same distance from the Earth. In this binary system, Sirius A is much brighter but Sirius B is much hotter. From this information, what can you conclude about the two stars?

A) Sirius B must be much smaller than Sirius A.
B) Sirius B must be much larger than Sirius A.
C) Sirius B must be much more massive than Sirius A.
D) Sirius B must be much less massive than Sirius A.

Question 29

The star named Circini has the spectral type and luminosity class of O 8.5 V. Based on this information, how does Circini compare to the Sun?

A) Circini is cooler and larger than the Sun.
B) Circini is cooler and smaller than the Sun.
C) Circini is hotter and more luminous than the Sun.
D) Circini is hotter and less luminous than the Sun.

Question 30

The star named Sheat is of spectral type M2 and luminosity class II. Based on this information, how does Sheat compare to the Sun?

A) Sheat is cooler and larger than the Sun.
B) Sheat is cooler and smaller than the Sun.
C) Sheat is hotter and more luminous than the Sun.
D) Sheat is hotter and larger than the Sun.

Question 31

What is the spectral sequence in order of increasing temperature?

A) MKFAGBO
B) BAFGKMO
C) MKGFABO
D) ABFMKGO

Question 32

Which star in the table has the largest diameter?

A) δ Cen
B) HR 4758
C) HD 39801
D) 9 CMa

Question 33

Why do white dwarfs have very low luminosities?

A) They are very small.
B) They have cooled down after leaving the main sequence.
C) They have very low mass.
D) White light is dimmer than blue or red light.

Question 34

How do we know that giant stars are larger in diameter than the Sun?

A) They are more luminous but have about the same temperature.
B) They are less luminous but have about the same temperature.
C) They are hotter but have about the same luminosity.
D) They are cooler but have about the same luminosity.

Question 35

Where are red giant stars found in the Hertzsprung-Russell diagram?

A) above the main sequence
B) below the main sequence
C) on the lower main sequence
D) on the upper main sequence

Question 36

A certain star moves from the middle toward the top right of the Hertzsprung-Russell diagram. How is the star changing?

A) It is moving farther away from the Sun in space.
B) It is getting dimmer and hotter.
C) It is getting larger and cooler.
D) It is getting brighter and smaller.

Question 37

Use the Hertzsprung-Russell diagram to answer the following question: Which star in the diagram is most like the Sun?

A) Alnilam
B) Arcturus
C) HR 5337
D) Sirius B

Question 38

What properties of a star determine its luminosity?

A) distance and diameter
B) temperature and distance
C) temperature and diameter
D) apparent magnitude and temperature

Question 39

In a Hertzsprung-Russell diagram, where are the stars with the smallest radius found?

A) in the upper left corner
B) in the upper right corner
C) in the lower left corner
D) in the lower right corner

Question 40

The table lists the spectral types for each of four stars. Which star in this table would have the lowest surface temperature?

A) α For
B) ο Cet
C) γ Tri
D) ξ Per

Question 41

If the orbital velocity of the lower-mass star in an eclipsing binary is 97 km/sec and it is completely eclipsed by the more massive star for 2 hours, what is the approximate diameter of the more massive star?

A) 194 km
B) 4656 km
C) 350,000 km
D) 700,000 km

Question 42

Compared with the spectral lines in the solar spectrum, how are lines in a supergiant star's spectrum different?

A) They are narrower.
B) They are broader.
C) They are weaker.
D) They are stronger.

Question 43

Consider two binary star systems, A and B, in which the distance between the stars is the same. If the total mass of the stars in system A is greater than the total mass of the stars in system B, which of following can you conclude?

A) The primary in A is closer to the centre of mass than the primary in B.
B) The primary in A is farther from the centre of mass than the primary in B.
C) The orbital period of the stars in A is shorter than the orbital period of the stars in B.
D) The orbital period of the stars in A is longer than the orbital period of the stars in B.

Question 44

Which of the following describes the method of spectroscopic parallax?

A) Estimate the distance to a star using its apparent brightness and luminosity class.
B) Estimate the distance to a star using the amount that it moves relative to more distant stars over a year.
C) Measure the spectrum of a star using the amount that it moves relative to more distant stars over a year.
D) Measure the spectrum of a star using its apparent brightness and luminosity class.

Question 45

An eclipsing binary has been analyzed and it has been determined that the ratio of the mass of star A to the mass of star B is about 6 : 1, and that the total mass of the two stars is 26 solar masses. What are the masses of star A and star B?

A) Star A has a mass of 6 solar mass and star B has a mass of 1 solar masses.
B) Star A has a mass of 20 solar masses and star B has a mass of 6 solar masses.
C) Star A has a mass of 22.3 solar masses and star B has a mass of 3.7 solar masses.
D) Star A has a mass of 31.2 solar masses and star B has a mass of 5.2 solar masses.

Question 46

In a binary system, where will the more massive star be found?

A) at the centre of mass
B) farthest from the centre of mass
C) nearest the centre of mass
D) following the largest orbit

Question 47

What would be the most reliable way to measure the mass of a star for which the distance is unknown?

A) apply the mass-temperature relation
B) measure its orbit around another star
C) measure its radius, then compute its volume and multiply by density to get the mass
D) compute its spectroscopic parallax, then apply the mass-luminosity relation

Question 48

What does a spectroscopic binary show periodic variations in?

A) brightness
B) motion perpendicular to the line of sight
C) motion along the line of sight
D) spectral type

Question 49

Why are spectroscopic binaries difficult to analyze?

A) We can't see the shape or tilt of the orbit.
B) We can't find the diameters of the stars.
C) We can't determine the luminosities of the stars.
D) The Doppler shift is not measurable.

Question 50

If we can solve the orbital motion of a spectroscopic binary, what can we find?

A) the mass of each star
B) the diameter of each star
C) the orbital period
D) the sum of the stars' masses

Question 51

The diagram illustrates two stars in a visual binary system and the centre of mass of this system. Based on this diagram, what is the ratio of the mass of star A to the mass of star B?

A) 2 to 1
B) 1 to 2
C) 2 to 3
D) 3 to 2

Question 52

In what kind of star are the hydrogen lines narrowest?

A) supergiants
B) main-sequence stars
C) subgiants
D) dwarfs

Question 53

You observe a spectroscopic binary star system. If you measure Doppler shifts in the spectrum and determine that star A is blueshifted and star B is redshifted, what can you conclude about the stars?

A) Star B is receding and star A is approaching.
B) Star B is approaching and star A is receding.
C) The stars are perpendicular to the line of sight.
D) Star A is moving faster than star B.

Question 54

To determine the orbital period of a visual binary, what must we measure?

A) position on the sky
B) brightness
C) luminosity
D) temperature

Question 55

Which of the following is a characteristic of an eclipsing binary?

A) It will be more luminous than a visual binary.
B) It will also be observed as a spectroscopic binary.
C) It will show a constant Doppler shift in its spectral lines.
D) It will show two stars with variable proper motion.

Question 56

At what point in the eclipsing binary light curve shown in the diagram is the cooler star in front of the hotter star?

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

Question 57

How is a luminosity class assigned to a star?

A) by combining the apparent magnitude with the star's parallax
B) by measuring the period of variability in the star's apparent magnitude
C) by studying the absorption line width in the spectrum of the star
D) by observing the angular size of the star's image in a photograph or digital image

Question 58

In the light curve shown in the diagram, what is the period of the eclipsing binary?

A) 5 days
B) 32.5 days
C) 42.5 days
D) 50 days

Question 59

What is the most reliable way to measure the mass of a star for which the distance is known?

A) Apply the mass-luminosity relation.
B) Measure its orbit around another star.
C) Measure its radius, then compute its volume and multiply by density to get the mass.
D) Apply the mass-temperature relation.

Question 60

Use the Hertzsprung-Russell diagram to answer the following question: Which star in the diagram has the largest absolute visual magnitude?

A) Antares
B) Arcturus
C) HR 5337
D) Sirius B

Question 61

Most stars on the Hertzsprung-Russell diagram are on the _______ ____________.

Question 62

What property do most of the nearest stars in the sky share?

A) They have high temperatures.
B) They are very luminous.
C) They are main-sequence stars.
D) They are red dwarfs.

Question 63

Define the range of a property as the maximum value divided by the minimum value. Which property of stars has the greatest range?

A) mass
B) radius
C) luminosity
D) temperature

Question 64

If you know the apparent brightness of a star and its intrinsic brightness you can easily find its ____________.

Question 65

____________________ can be used to determine the distance to a star, when the spectrum of the star can be used to determine its spectral type and luminosity class.

Question 66

Which of the following pieces of information are needed to calculate the total mass of a binary system?

A) the ratio of the angular separation from the centre of mass of each of the stars
B) the size of the orbits and the orbital period
C) the radial velocities of the two stars
D) the time required for the small star to eclipse the larger star

Question 67

Which star type in the Milky Way is likely to be most completely catalogued?

A) red main-sequence stars, because there are so many of them
B) luminous stars, because they are bright and easy to find
C) stars like the Sun, because the Sun is a typical star
D) white dwarf stars, because they are so old

Question 68

Which of the following kinds of stars best obey the mass-luminosity relation?

A) main-sequence stars
B) giant stars
C) supergiant stars
D) white dwarfs

Question 69

Luminosity class IV objects are known as ____________________.

Question 70

This diagram shows the velocity along the line of sight (labelled v_r) for two stars in a spectroscopic binary. Which of the stars is most massive? ____________________

Question 71

What type of stars are the most common?

A) supergiants
B) giants
C) upper (more luminous) main-sequence stars
D) lower (less luminous) main-sequence stars

Question 72

Based on the mass-luminosity relation, approximately what luminosity would a 2 solar mass star on the main sequence have?

A) 0.5 solar luminosities
B) 2 solar luminosities
C) 4 solar luminosities
D) 11 solar luminosities

Question 73

Which one of the following kinds of stars is most dense?

A) a supergiant star
B) a main-sequence star
C) a giant star
D) a white dwarf

Question 74

The strength of a star's spectral lines can be used to determine its ____________.

Question 75

Which stars on the main sequence have the greatest mass?

A) the spectral type M stars
B) the spectral type O stars
C) the stars in the lower right of the Hertzsprung-Russell diagram
D) the stars in the lower left of the Hertzsprung-Russell diagram

Question 76

If you took a random sample of 100 main-sequence stars in the Sun's neighbourhood, what would you expect their total mass to be?

A) Much less than 1 solar mass.
B) About 1 solar mass.
C) About 10 solar masses.
D) About 100 solar masses.

Question 77

A G2 I star is ____________________ in diameter and ____________________ luminous than the Sun.

Question 78

The largest of the red stars are the ____________________ stars.

Question 79

What property do most of the (apparently) bright stars in the sky share?

A) They are close to Earth.
B) They are very luminous.
C) They are main-sequence stars.
D) They are red dwarfs.

Question 80

The apparent visual magnitude a star would have from 33 ly away is called the ________ _____________ ____________.