Deck 6: The Family of Stars

Question 1

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

Answer 1

the apparent magnitude of a star observed from a distance of 10 parsecs

Question 2

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.

Answer 2

Circini is hotter and more luminous than the Sun.

Question 3

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.

Answer 3

They are more luminous but have about the same temperature.

Question 4

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 5

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 6

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 7

Use the H-R 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 8

Where are red giant stars found in the H-R diagram?

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

Question 9

In what kind of type A star are the hydrogen lines narrowest?

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

Question 10

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 11

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 12

In an H-R 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 13

In an H-R 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 14

Use the H-R 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 15

Use the H-R 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 16

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

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

Question 17

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 18

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 19

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 20

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 21

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

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

Question 22

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 23

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 24

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 25

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 26

What does a spectroscopic binary show periodic variations in?

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

Question 27

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 28

Which 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 29

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 30

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 : 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 1 solar mass and star B has a mass of 6 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 31

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 32

$$\begin{array} { | l | c | c | } \hline { \text { Star } } & \begin{array} { c } \text { Parallax } \\\text { (sec of arc) }\end{array} & \begin{array} { c } \text { Spectral } \\\text { Type }\end{array} \\\hline 5 \text { Cen } & 0.026 & \text { B2 IV } \\\hline \text { HR 4758 } & 0.05 & \text { G0 V } \\\hline \text { HD 39801 } & 0.005 & \text { M2 I } \\\hline 9 \mathrm { CMa } & 0.4 & \text { Al V } \\\hline\end{array}$$

-Which star in the table has the highest surface temperature?

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

Question 33

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

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

Question 34

$$\begin{array} { | l | c | c | } \hline { \text { Star } } & \begin{array} { c } \text { Parallax } \\\text { (sec of arc) }\end{array} & \begin{array} { c } \text { Spectral } \\\text { Type }\end{array} \\\hline 5 \text { Cen } & 0.026 & \text { B2 IV } \\\hline \text { HR 4758 } & 0.05 & \text { G0 V } \\\hline \text { HD 39801 } & 0.005 & \text { M2 I } \\\hline 9 \mathrm { CMa } & 0.4 & \text { Al V } \\\hline\end{array}$$

-Which star in the table has the largest diameter?

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

Question 35

$$\begin{array} { | l | c | c | } \hline { \text { Star } } & \begin{array} { c } \text { Parallax } \\\text { (sec of arc) }\end{array} & \begin{array} { c } \text { Spectral } \\\text { Type }\end{array} \\\hline 5 \text { Cen } & 0.026 & \text { B2 IV } \\\hline \text { HR 4758 } & 0.05 & \text { G0 V } \\\hline \text { HD 39801 } & 0.005 & \text { M2 I } \\\hline 9 \mathrm { CMa } & 0.4 & \text { Al V } \\\hline\end{array}$$

-Which star in the table is the closest to Earth?

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

Question 36

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

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

Question 37

The diagram shows the radial velocity curve of a double-line spectroscopic binary.Based on this radial velocity curve,what is the mass of star B compared to star A?

A)Star B is one-tenth the mass of star A.
B)Star B is half the mass of star A.
C)Star B is twice the mass of star A.
D)Star B is ten times the mass of star A.

Question 38

Which stars on the main sequence have the greatest mass?

A)the spectral type M stars
B)the spectral type O stars
C)those that are located in the lower right of the H-R diagram
D)those that are located in the lower left of the H-R diagram

Question 39

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 semi major axis and period of the orbit
C)the radial velocities of the two stars
D)the time required for the small star to eclipse the larger star

Question 40

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 330 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 41

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 42

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.

Question 43

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 44

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 45

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 46

What is 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 47

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 48

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 49

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 50

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)o Cet
C)ƴ Tri
D)

Question 51

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 the two 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)As we move our heads from side to side, our brain compares look angles from each of these positions to work out the distance to the object viewed.

Question 52

Which of the following can we NOT use to determine the surface temperature of a star?

A)studying its continuous spectrum
B)studying its line absorption spectrum
C)measuring the star's luminosity and diameter
D)measuring the star's parallax

Question 53

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 54

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.

Question 55

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 56

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 57

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 58

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 59

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 60

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)o Cet
C)ƴ Tri
D)

Question 61

For stars on the main sequence,the luminosity can be estimated by the formula L = ____________________.

Question 62

If we divide the mass of a star by its volume,we calculate the star's ____________________.

Question 63

The most common kinds of stars are low luminosity stars.

Question 64

Supergiants are about as common as the Sun.

Question 65

A star with a parallax of 0.01 seconds of arc is at a distance of 1000 parsecs.

Question 66

The largest of the red stars are the ____________________ stars.

Question 67

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

Question 68

The parallax of the star 75 Leo is 0.10 and its apparent visual magnitude is +5.18.The absolute visual magnitude of 75 Leo is ____________________.

Question 69

Most stars on the H-R diagram are on the ___________________.

Question 70

If a star is twice as hot as the Sun and only half the Sun's diameter,it will be less luminous than the Sun.

Question 71

The absolute magnitude of a star is the apparent magnitude it would have if it were 33 light years from Earth.

Question 72

Absorption lines in the spectra of supergiant stars are broader than the same spectral lines in main-sequence stars of the same spectral type.

Question 73

The location of a star in the H-R diagram indicates its temperature and intrinsic brightness.

Question 74

Luminosity class IV objects are known as ____________________.

Question 75

The method of spectroscopic parallax cannot be applied to stars more that about 300 light years distant.

Question 76

On the H-R diagram,indicate the location of the white dwarf stars.

Question 77

The masses and diameters of each star in a binary can be determined from ____________________ binaries.

Question 78

Look carefully at this diagram of a radial velocity curve for a spectroscopic binary.Which of the stars is most massive? ____________________

Question 79

____________________ 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 80

Giant stars are members of luminosity class III.