Deck 8: The Family of Stars

Question 1

Parallax would be easier to measure if

A) Earth's orbit was larger.
B) the stars were farther away.
C) Earth moved faster along its orbit.
D) Earth's orbit was larger, the stars were further away, and Earth moved faster along its orbit.
E) None of the other choices are correct.

Answer 1

A

Question 2

We know that giant stars are larger in diameter than the Sun because

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.
E) they have a larger absolute magnitude than the Sun.

Answer 2

A

Question 3

The star named Circini has the spectral type and luminosity class of O 8.5 V. Based on this information, which of the following are true?
I) Circini has a surface temperature less than the Sun.
II) Circini has a diameter that is greater than that of the Sun.
III) Circini is more luminous than the Sun.
IV) Circini is located near the upper left-hand corner in the H-R diagram.

A) I & II
B) II & IV
C) II, III, & IV
D) I, II, & III
E) I, II, III, & IV

Answer 3

C

Question 4

In the H-R diagram, roughly 80 percent of all stars are

A) in the giant region.
B) in the supergiant region.
C) among the B stars.
D) among the G stars.
E) on the main sequence.

Question 5

In an H-R diagram, stars with the smallest radius are found in the _________ of the diagram.

A) center
B) upper left corner
C) upper right corner
D) lower left corner
E) lower right corner

Question 6

A star's luminosity depends only on the star's

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

Question 7

The star named Sheat is of M2 II spectral type and luminosity class. Based on this information, which of the following are true?
I) Sheat has a surface temperature less than the Sun.
II) Sheat has a diameter that is greater than that of the Sun.
III) Sheat is more luminous than the Sun.
IV) Sheat is located near the upper left-hand corner in the H-R diagram.

A) I & II
B) II & IV
C) II, III, & IV
D) I, II, & III
E) I, II, III, & IV

Question 8

The ________ of a star is a measure of the total energy radiated by the star in one second.

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

Question 9

An eclipsing binary will

A) be more luminous than a visual binary.
B) also be observed as a spectroscopic binary.
C) give off most of its light in the infrared.
D) show a constant Doppler shift in its spectral lines.
E) show two stars with variable proper motion.

Question 10

In a binary system, the more massive star

A) is at the center of mass.
B) is farthest from the center of mass.
C) is nearest the center of mass.
D) follows the largest orbit.
E) shows a larger Doppler shift in its spectral lines.

Question 11

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

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

Question 12

If we can solve the orbital motion of an eclipsing binary, we can find

A) the mass of each star.
B) the diameter of each star.
C) the distance to the binary.
D) all of the other choices.
E) the mass of each star and the diameter of each star.

Question 13

The most common stars are

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

Question 14

Red giant stars are
I) more luminous than the Sun.
II) larger in diameter than the Sun.
III) cooler than B stars.
IV) located above the main-sequence stars in the H-R diagram.

A) I & II
B) II & IV
C) I, II, & IV
D) II, III, & IV
E) I, II, III, & IV

Question 15

Diagram 8-1 Use the H-R diagram below to answer the following question(s).
Which star in Diagram 8-1 is most like the Sun?

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

Question 16

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

A) more narrow.
B) broader.
C) weaker.
D) stronger.
E) broader and weaker.

Question 17

Absolute visual magnitude is

A) the apparent magnitude of a star observed from Earth.
B) the luminosity of a star observed from a distance of 1000 pc.
C) the apparent magnitude of a star observed from a distance of 10 pc.
D) the luminosity of a star observed from Earth.
E) the apparent magnitude of a star observed from a distance of 10 pc and the luminosity of a star observed from Earth.

Question 18

Diagram 8-1 Use the H-R diagram below to answer the following question(s).
Which star in Diagram 8-1 has the greatest surface temperature?

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

Question 19

The hydrogen lines in spectral type A stars

A) are most narrow for supergiants.
B) are most narrow for main-sequence stars.
C) can not be used to estimate the luminosity of the star.
D) are very weak and difficult to see.
E) are useful in determining the apparent magnitude of the star.

Question 20

The total mass of the pair of stars in spectroscopic binaries are difficult to estimate because

A) we can't measure the radial velocities of each star in the system.
B) we can't see the shape or tilt of the orbit.
C) we can't find the diameters of the stars.
D) we can't determine the luminosities of the stars.
E) the Doppler shift is not measurable.

Question 21

If a star with an absolute magnitude of − 5 has an apparent magnitude of +5, then its distance is

A) 1 pc.
B) 10 pc.
C) 100 pc.
D) 1000 pc.
E) 10,000 pc.

Question 22

The total mass of a binary system can be calculated from

A) the ratio of the angular separation from the center of mass of each of the stars.
B) the distance to the binary and its radial velocity.
C) the semimajor axis and period of the orbit.
D) the radial velocities of the two stars.
E) the time required for the smaller star to eclipse the larger star.

Question 23

Table 8-1 Use the chart below to answer the following question(s).
From the data given, which star in Table 8-1 is the closest to Earth?

A) 65 Tau
B) HR 4621
C) α Pic
D) 58 Ori
E) HR 2491

Question 24

Table 8-1 Use the chart below to answer the following question(s).
From the data given, which star in Table 8-1 has the greatest surface temperature?

A) 65 Tau
B) HR 4621
C) α Pic
D) 58 Ori
E) HR 2491

Question 25

A spectroscopic binary shows periodic variations in its

A) radial velocity.
B) proper motion.
C) brightness.
D) mass.
E) spectral type.

Question 26

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
E) All of the other choices are correct.

Question 27

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 6 and 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 1 solar mass and star B has a mass of 6 solar masses.
B) Star A has a mass of 20 solar mass and star B has a mass of 6 solar masses.
C) Star A has a mass of 31.2 solar mass and star B has a mass of 5.2 solar masses.
D) Star A has a mass of 22.3 solar mass and star B has a mass of 3.7 solar masses.
E) The masses of star A and star B cannot be determined from the information given.

Question 28

The diagram below shows the radial velocity curve of a double-line spectroscopic binary. Based on this radial velocity curve, which of the following statements is correct?

A) Star A is twice the mass of star B.
B) Star B is twice the mass of star A.
C) Star A is ten times the mass of star B.
D) Star B is ten times the mass of star A.
E) Star A and Star B have the same mass.

Question 29

What is the total mass of a binary star system with P = 20 yr and a = 10 AU?

A) 2 solar masses
B) 2.5 solar masses
C) 0.5 solar mass
D) 80 solar masses
E) 0.4 solar mass

Question 30

If a star has a parallax of 0.02 seconds of arc, then its distance is

A) 20 pc.
B) 50 pc.
C) 2 pc.
D) 5 pc.
E) 500 pc.

Question 31

Table 8-1 Use the chart below to answer the following question(s).
From the data given, which star in Table 8-1 has the greatest diameter?

A) 65 Tau
B) HR 4621
C) α Pic
D) 58 Ori
E) HR 2491

Question 32

The diagram below illustrates two stars in a visual binary system and the center 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
E) 1 to 3

Question 33

In the light curve below, what is the period of the eclipsing binary?

A) 5 days
B) 32.5 days
C) 7.5 days
D) 42.5 days
E) 50 days

Question 34

Table 8-2 Use the chart below to answer the following question(s).
Which star in Table 8-2 is the closest to Earth?

A) δ Cen
B) HR 4607
C) HR 4758
D) HD 39801
E) 9 CMa

Question 35

Table 8-1 Use the chart below to answer the following question(s)
From the data given, which star in Table 8-1 would appear the faintest in the night sky?

A) 65 Tau
B) HR 4621
C) α Pic
D) 58 Ori
E) HR 2491

Question 36

Stars on the main sequence with the greatest mass

A) are spectral type M stars.
B) are spectral type O stars.
C) are located at the bottom of the main sequence in the H-R diagram.
D) have masses very similar to the Sun.
E) are spectral type O stars and are located at the bottom of the main sequence in the H-R diagram.

Question 37

Table 8-1 Use the chart below to answer the following question(s).
From the data given, which star in Table 8-1 has the greatest luminosity?

A) 65 Tau
B) HR 4621
C) α Pic
D) 58 Ori
E) HR 2491

Question 38

The star Algol is

A) an astrometric binary.
B) a spectroscopic binary.
C) a visual binary.
D) an eclipsing binary.
E) a spectroscopic binary and an eclipsing binary.

Question 39

At what point in the light curve below is the cooler star in front of the hotter star of an eclipsing binary system?
​
​

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

Question 40

Which of the following kind of stars is most dense?

A) a supergiant star
B) a main sequence star
C) a giant star
D) a white dwarf
E) the Sun

Question 41

Which stars always have large positive absolute magnitude?

A) stars of high luminosity
B) stars of low luminosity
C) nearby stars
D) distant stars
E) not enough information given

Question 42

The most accurate way to determine the surface temperature of a star is to study

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

Question 43

Table 8-2 Use the chart below to answer the following question(s).
Which star in Table 8-2 has the greatest diameter?

A) δ Cen
B) HR 4607
C) HR 4758
D) HD 39801
E) 9 CMa

Question 44

How do humans use their eyes to measure relative distance by parallax?

A) By continuously focusing our eyes on distant objects, we can determine distance.
B) Since our eyes are separated, the brain interprets the relative look angles of these eyes in terms of distance to the object viewed.
C) Our eyes can measure the time it takes light to travel from an object and from this we get distance.
D) By moving our heads from side to side our brain compares look angles from each of these positions to obtain the distance to the object viewed.

Question 45

Why don't we see hydrogen Balmer lines in the spectra of stars with temperatures of 45,000 K?

A) There is no hydrogen in stars this hot.
B) The stars are hot enough that most of the hydrogen is ionized and the atoms cannot absorb energy.
C) These stars are so cool that nearly all of the electrons in the hydrogen atom are in the ground state.
D) Stars of this temperature are too cool to produce an absorption spectrum.
E) Stars of this temperature are too hot to produce an absorption spectrum.

Question 46

Why don't we see hydrogen Balmer lines in the spectra of stars with temperatures of 3,200 K?

A) There is no hydrogen in stars this cool.
B) The stars are hot enough that most of the hydrogen is ionized and the atoms cannot absorb energy.
C) These stars are so cool that nearly all of the hydrogen atoms are in the ground state.
D) Stars of this temperature are too cool to produce an absorption spectrum.
E) Stars of this temperature are too hot to produce an absorption spectrum.

Question 47

If you compare two stars,

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 larger surface area has the greater energy flux from its surface.

Question 48

Five stars and their spectral types are given below. Which star would have the lowest surface temperature?

A) α For; F8
B) ο Cet; M7
C) 35 Ari; B3
D) γ Tri; A0
E) ξ Per; O7

Question 49

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 50

The spectral types for each of five stars are given. Which star in would have the greatest surface temperature?

A) α For; F8
B) ο Cet; M7
C) 35 Ari; B3
D) γ Tri; A0
E) ξ Per; O7

Question 51

We can determine the surface temperature of a star from

A) studying its continuous spectrum.
B) studying its line absorption spectrum.
C) measuring the star's luminosity.
D) studying its continuous spectrum and measuring the star's luminosity.
E) studying its continuous spectrum, studying its line absorption spectrum, and measuring the star's luminosity.

Question 52

Stars in the upper right part of the Hertzsprung-Russell diagram are always ____ when compared to stars near the middle of the diagram.

A) cooler
B) brighter as seen from Earth
C) larger
D) smaller
E) more massive

Question 53

The star HR 4621 has an apparent magnitude of 2.6 and an absolute magnitude of -0.3. This star is at a distance

A) closer than 10 pc.
B) farther than 10 pc.
C) No way to tell.

Question 54

The absorption lines in the visible portion of the spectrum of a star that are produced by hydrogen are from the

A) Lyman series.
B) Balmer series.
C) Paschen series.
D) isotopes of hydrogen.
E) ions of hydrogen.

Question 55

If the orbital velocity of an eclipsing binary is 97 km/s and the smaller star is completely eclipsed in 2 hours, what is the diameter of the smaller star?

A) 175,000 km
B) 350,000 km
C) 194 km
D) 700,000 km
E) 4656 km

Question 56

If two stars are emitting the same amount of light and are the same size, the star that is farther will appear

A) brighter.
B) dimmer.
C) redder.
D) bluer.
E) They will have the same brightness as seen from Earth.

Question 57

A star's absolute magnitude depends only on the star's

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

Question 58

Table 8-2 Use the chart below to answer the following question(s).
Which star in Table 8-2 has the greatest surface temperature?

A) δ Cen
B) HR 4607
C) HR 4758
D) HD 39801
E) 9 CMa

Question 59

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 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 Earth's movement around the Sun.

Question 60

From the mass-luminosity relation, a 2-solar-mass star on the main sequence would have a luminosity of approximately ____ solar luminosities.

A) 2
B) 4
C) 11
D) 0.5
E) 0.25

Question 61

Doppler-shift observations of a spectroscopic binary star can enable astronomers to calculate ________ of its individual stars.

A) the minimum masses
B) the sizes
C) both minimum masses and sizes
D) neither minimum masses nor sizes

Question 62

A star's apparent magnitude is a measure of

A) how bright it appears to us if it is at its actual distance.
B) how bright it appears to us at a standard distance of 10 pc.
C) its energy output per second compared to the Sun.
D) its mass in solar masses.
E) its surface temperature in Kelvin.

Question 63

Which one of the methods below enables astronomers to measure the distance of a star near the Sun in our galaxy?

A) sound echoes knowing the speed of sound and time
B) parallax using Earth's orbit
C) human binocular vision
D) Balmer series
E) none of the above

Question 64

Spectroscopic and eclipse duration observations of an eclipsing binary star can enable astronomers to calculate________ of its individual stars.

A) the masses
B) the sizes
C) the masses and sizes
D) neither masses nor sizes

Question 65

The mass of a visual binary pair of stars can be obtained from

A) the time in years for them to orbit one another.
B) the size of their orbit.
C) their apparent magnitudes.
D) both the time in years for them to orbit one another and the size of their orbit.

Question 66

A parsec is
I) a unit of length used in astronomy
II) 2.06 × 10⁵ AU
III) the distance to an imaginary star whose stellar parallax is one arc second
IV) 3.26 light years
V) the longest unit of length in astronomy

A) I, II, V
B) II, IV
C) I, III, IV, V
D) I, II, III, IV, IV

Question 67

Groombridge 34 is an M1 V star. Based on this information, which of the following are true?
I) Groombridge 34 has a surface temperature that is less than the Sun.
II) Groombridge 34 has a mass that is greater than that of the Sun.
III) Groombridge 34 is less luminous than the Sun.
IV) Groombridge 34 is located near the middle of the H-R diagram.

A) I & II
B) II & IV
C) I & IV
D) I & III
E) II & III

Question 68

The best sample of the true numbers of the different types of stars consists of

A) stars that appear brightest in the sky to an observer on Earth.
B) all of the stars within our solar system.
C) all the stars within a given distance from Earth.

Question 69

The two stars near one another are shown. Positions of one member are shown relative to the other star at different times. From plots like this one, astronomers conclude that

A) the stars are in an elliptical orbit around one another.
B) the mass of the pair can be estimated.
C) one star is passing by the other never to return.
D) both the stars are in an elliptical orbit around one another.

Question 70

The correct sequence of spectral type letters from hot on the left to cool on the right is

A) M, K, G, F, A, B, O
B) O, B, A, F, G, K, M
C) G, K, M, F, O, B, A
D) A, B, O, F, G, K, M

Question 71

Vega is an A0 V star. Based on this information, which of the following are true?
I) Vega has a surface temperature less than the Sun.
II) Vega has a mass that is greater than that of the Sun.
III) Vega is more luminous than the Sun.
IV) Vega is located in the upper left-hand corner in the H-R diagram.

A) I & II
B) II & III
C) II, III, & IV
D) I, II, & III
E) I, II, III, & IV

Question 72

A pair of stars orbit around one another in an elliptical orbit with a semi-major axis, a , of 1 AU with an orbital period, P , of 1 year. What is the mass of the pair of stars?

A) 1 solar masses
B) 2 solar masses
C) 4 solar masses
D) 8 solar masses
E) 16 solar masses

Question 73

Two stars of the same spectral class must have the same

A) radius.
B) temperature.
C) mass.
D) distance.
E) all of the other choices.

Question 74

The absorption lines in the ultraviolet portion of the spectrum of a star that are produced by hydrogen are from the

A) Lyman series.
B) Balmer series.
C) Paschen series.
D) isotopes of hydrogen.
E) ions of hydrogen.

Question 75

The absorption lines in the infrared portion of the spectrum of a star that are produced by hydrogen are from the

A) Lyman series.
B) Balmer series.
C) Paschen series.
D) isotopes of hydrogen.
E) ions of hydrogen.

Question 76

Binary (double) stars can be detected by

A) being seen as two separate stars with a telescope.
B) one star traveling a wiggly proper-motion path across the sky.
C) one star dimming abruptly as another passes in front of it.
D) pairs of absorption lines seen in the spectrum of what appears to be one star.
E) All of the other choices are correct.

Question 77

The spectra of the coolest stars contain strong absorption features (or lines) of

A) TiO molecules.
B) ionized helium.
C) helium.
D) hydrogen.
E) All of the other choices are correct.

Question 78

Compared with the spectral lines in the solar spectrum, lines in a supergiant spectrum are

A) sharper.
B) broader.
C) weaker.
D) stronger.
E) broader and weaker.

Question 79

We know the white dwarf star Sirius B has a mass comparable to the Sun because

A) of its measured color.
B) of its measured temperature compared to Sirius A.
C) it is part of binary star system with Sirius A.

Question 80

We know that the numbers of stars _________ from _______ to ________ on the H-R diagram.

A) increases, upper right, lower left
B) decreases, upper left, lower right
C) increases, upper left, lower right
D) decreases, upper right, lower left