Deck 17: The Stars: Giants, Dwarfs, and the Main Sequence

Question 1

The Hipparcos mission's data on parallaxes is useful for stellar distances out to about 200 pc.

Answer 1

True

Question 2

On the main sequence, almost all stars have radii between about 0.1 and 10 times the Sun.

Answer 2

True

Question 3

First magnitude Spica appears 2.5 times brighter than second magnitude Polaris.

Answer 3

True

Question 4

The proper motion of a star, its distance, and Doppler shift can give us its space velocity.

Question 5

About 500 stars can be seen by the naked eye from somewhere on Earth.

Question 6

Like the Sun, main sequence stars are converting hydrogen into helium in their cores.

Question 7

In a binary system, the more massive stars always stay closer to the center of mass and moveslower.

Question 8

For luminosity classification, fat stars have skinny spectral lines.

Question 9

The vast majority of stars near us would fall to the bottom right on the H-R diagram.

Question 10

The proper motion of a star is its true velocity through space.

Question 11

If a star were moved 10 times farther away, its apparent magnitude would drop by fivemagnitudes.

Question 12

The nearest naked-eye star to our Sun, Alpha Centauri, is still over a parsec distant.

Question 13

The Sun's complete classification is $\text { G2V. }$

Question 14

If a star were moved 10 times farther away, its absolute magnitude would drop fivemagnitudes.

Question 15

A star of the Sun's diameter, but twice as hot, must be 16X more luminous than the Sun.

Question 16

In a spectroscopic binary, the star whose lines shift the most weighs the most.

Question 17

Hydrogen lines are weaker in both very hot and very cool stars.

Question 18

Star A and star B have the same apparent magnitude. Star A is twice as distant as star B.Therefore, star A has twice the luminosity as star B.

Question 19

A type B9 star is hotter than a type A0.

Question 20

Eclipsing binaries are the most useful, giving us sizes as well as masses of the pair.

Question 21

If a star is found by spectroscopic observations to be about 500 parsecs distant, its parallax is:

A).2".
B).5".
C).02".
D).002".
E).005".

Question 22

If a star has a parallax of 0.05", then its distance in light-years is about:

A)6.4 light-years.
B)12.7 light-years.
C)20 light-years.
D)65 light-years.
E)100 light-years.

Question 23

Which statement about stellar motion is incorrect?

A)In general, the closer a star is, the more its proper motion.
B)The radial velocity is measured by the Doppler shift.
C)The transverse velocity is measured by the proper motion and the distance.
D)Like parallax, proper motion is measured over intervals of exactly six months.
E)The Pythagorean theorem relates space, transverse, and radial velocities.

Question 24

About how many stars has the Hipparcos mission given us accurate distance data on?

A)about 3,000, about half of what you can see with the naked eye alone
B)over 6000, the visible naked eye stars and some seen in binoculars
C)60,000, those within about 100 light-years of us
D)a million, those with parallaxes of .005" or larger
E)over 100 billion, almost every star in the galaxy

Question 25

The ESA's GAIA project will be able to measure parallax and stellar properties of about howmany stars?

A)one million
B)ten thousand
C)one billion
D)one hundred billion
E)None; it has a different purpose.

Question 26

Procyon lies about 13 light-years distant, thus its parallax is about:

A)0.01".
B)0.25".
C)0.40".
D)0.65".
E)1.3".

Question 27

A nearby star has a parallax of 0.2 arc seconds. What is its distance?

A).1 parsec
B).2 parsec
C).5 parsec
D)5 parsecs
E)50 parsecs

Question 28

Which of the following best describes the size and distance relationship of our Sun and thenearest star?

A)a tennis ball here, another on the Moon
B)two beach balls separated by 100 city blocks
C)two grains of sand separated by 100 light-years
D)two marbles separated by 300 kilometers
E)two baseballs separated by 100 yards

Question 29

About how many stars can be seen from somewhere on Earth with the naked eye?

A)600
B)6,000
C)600,000
D)6,000,000
E)uncountably many

Question 30

If a star appears to move relative to other stars over a one-year period, this motion is due tothe star's

A)transverse motion.
B)radial motion.
C)parallax shift.
D)Doppler shift.
E)true space motion.

Question 31

The absolute magnitude of a star is its brightness as seen from a distance of:

A)one million kilometers.
B)one astronomical unit.
C)one light-year.
D)ten parsecs.
E)10 light-years.

Question 32

If a star appears to move back and forth relative to other stars over a six-month period, thismotion is due to the star's:

A)transverse motion.
B)radial motion.
C)parallax shift.
D)Doppler shift.
E)true space motion.

Question 33

High mass stars provide most of the mass and most of the light in galaxies.

Question 34

The Hipparcos mission's observations have given us good data on stars out to about:

A)100 light-years.
B)200 light-years.
C)200 parsecs.
D)1000 light-years.
E)1000 parsecs.

Question 35

What is the absolute magnitude of our Sun?

A)-23.0
B)-4.6
C)-1.4
D)+4.8
E)+9.4

Question 36

In order to turn a star's proper motion into its space velocity, we must also know:

A)its mass and spectral type.
B)its temperature and age.
C)its distance and radial velocity.
D)its distance and mass.
E)its spectral type and period of rotation.

Question 37

A star of ten solar masses would probably stay stable on the main sequence only about1/1000th as long as our Sun.

Question 38

The motion of a star towards or away from us is called its:

A)transverse motion.
B)radial motion.
C)parallax shift.
D)Doppler shift.
E)true space motion.

Question 39

Gaia will be able to measure which two apparent motions of stars?

A)transverse and radial
B)parallax and transverse
C)radial and parallax
D)parallax and orbital
E)orbital and radial

Question 40

What is proper motion?

A)It is the true, not apparent, motion of a star in space.
B)It is the apparent shift as we go to opposite sides of our orbit every six months.
C)It is the annual apparent motion of a star across the sky.
D)It is the motion of a star towards or away from us, revealed by Doppler shifts.
E)It is the orbital motion of a star around the Galaxy.

Question 41

On the H-R diagram, the Sun lies:

A)at the top left.
B)at the bottom left.
C)at the bottom right.
D)about the middle of the main sequence.
E)at the top right.

Question 42

Star A and star B both have an absolute magnitude of 2.0, but star A has an apparentmagnitude of 5.0 and star B has an apparent magnitude of 7.0. Which statement below is correct?

A)Star A appears brighter than star B, but actually star B and star A are the same brightness.
B)Star B appears brighter than star A, but actually star B and star A are the same brightness.
C)Star A and star B appear to have the same brightness, but actually star B is brighter than starA.
D)Star A and star B appear to have the same brightness, but actually star A is brighter than starB.
E)It is impossible to determine how bright these stars are or appear to be relative to one another,given the information above.

Question 43

At the distance of Jupiter (6 times further away from the Sun than Earth)the amount ofsunlight received per square centimeter is different by what factor?

A)6 times less
B)12 times less
C)36 times less
D)6 times more
E)12 times more

Question 44

What physical property of a star does the spectral type measure?

A)density
B)luminosity
C)temperature
D)mass
E)composition

Question 45

Star A is a main sequence star of spectral type $\mathrm { F 2}$ ad star B is a white dwarf of spectral typeB4. Which statement below is correct?

A)Star A appears brighter than star B.
B)Star B appears brighter than star A.
C)Star A is hotter than star B.
D)Star B is hotter than star A.
E)None of the above can be said about these two stars.

Question 46

The Hertzsprung-Russell Diagram plots ________ against the spectral type or temperature.

A)distance
B)luminosity or absolute magnitude
C)brightness or apparent magnitude
D)size or density
E)mass

Question 47

The most famous G type star is:

A)Polaris.
B)Betelguese.
C)Sirius.
D)the Sun.
E)Pollux.

Question 48

Star A is a main sequence star of spectral type G5 and star B is a red giant of spectral typeK2. Which statement below is correct?

A)Star A appears brighter than star B.
B)Star B appears brighter than star A.
C)Star A is hotter than star B.
D)Star B is hotter than star A.
E)None of the above can be said about these two stars.

Question 49

Perhaps the greatest of the Greek astronomers, ________ compiled the first catalog of stars,accurately measured their positions, and defined the basic system of stellar brightnesses.

A)Erastothenes
B)Aristotle
C)Ptolemy
D)Hipparchus
E)Aristarchus

Question 50

Two red stars have surface temperatures of 3000 K, but Star A's luminosity is about 5% ofthe Sun's and Star B's luminosity is about 32,000 times the luminosity of the Sun. How muchbigger is star B than star A?

A)They are the same size.
B)Star B's radius is about 16 times larger than star A's radius.
C)Star B's radius is about 800 times larger than star A's radius.
D)Star B's radius is about 640,000 times larger than star A's radius.
E)This cannot be determined from the information given.

Question 51

Star A and star B both have an apparent magnitude of 4.0, but star A has an absolutemagnitude of 1.0 and star B has an absolute magnitude of 7.0. Which statement below is correct?

A)Star A appears brighter than star B, but actually star B and star A are the same brightness.
B)Star B appears brighter than star A, but actually star B and star A are the same brightness.
C)Star A and star B appear to have the same brightness, but actually star B is brighter than starA.
D)Star A and star B appear to have the same brightness, but actually star A is brighter than starB.
E)It is impossible to determine how bright these stars are or appear to be relative to one another,given the information above.

Question 52

Which of the following is the most common type of star?

A)high mass main sequence
B)low mass main sequence
C)white dwarfs
D)red giants
E)blue supergiants

Question 53

Star A has an absolute magnitude of 2.5 and star B has an apparent magnitude of 2.5, but starA is a main sequence star and star B is a red giant. Which statement below is correct?

A)Star A appears brighter than star B, but actually star B and star A are the same brightness.
B)Star B appears brighter than star A, but actually star B and star A are the same brightness.
C)Star A and star B appear to have the same brightness, but actually star B is brighter than starA.
D)Star A and star B appear to have the same brightness, but actually star A is brighter than starB.
E)It is impossible to determine how bright these stars are or appear to be relative to one another,given the information above.

Question 54

Star A and star B both have an absolute magnitude of 2.0, but star A is at a distance of 50 pcand star B is at a distance of 20 pc. Which statement below is correct?

A)Star A appears brighter than star B, but actually star B and star A are the same brightness.
B)Star B appears brighter than star A, but actually star B and star A are the same brightness.
C)Star A and star B appear to have the same brightness, but actually star B is brighter than starA.
D)Star A and star B appear to have the same brightness, but actually star A is brighter than starB.
E)It is impossible to determine how bright these stars are or appear to be relative to one another,given the information above.

Question 55

Compared to the size of the Sun, in what range of sizes are nearly all stars found?

A).5 to 2 solar radii
B)0.1 to 1.0 solar radii
C)0.5 to 50 solar radii
D)1 to 100 solar radii
E)0.01 to 100 solar radii

Question 56

Star A and star B both have an apparent magnitude of 7.0, but star A is at a distance of 15 pcand star B is at a distance of 30 pc. Which statement below is correct?

A)Star A appears brighter than star B, but actually star B and star A are the same brightness.
B)Star B appears brighter than star A, but actually star B and star A are the same brightness.
C)Star A and star B appear to have the same brightness, but actually star B is brighter than starA.
D)Star A and star B appear to have the same brightness, but actually star A is brighter than starB.
E)It is impossible to determine how bright these stars are or appear to be relative to one another,given the information above.

Question 57

In comparing first magnitude Deneb with second magnitude Polaris, we find that:

A)Polaris is in reality much more luminous.
B)Deneb must be much hotter than Polaris.
C)Deneb appears 2.5 times brighter to us than does Polaris.
D)Polaris is really 100 times brighter than nearby Deneb.
E)Deneb is really much closer than Polaris.

Question 58

Stars that have masses similar to the Sun's, and sizes similar to the Earth are:

A)main sequence stars.
B)white dwarfs.
C)red giants.
D)red dwarfs.
E)brown dwarfs.

Question 59

What are the two most important intrinsic properties used to classify stars?

A)mass and age
B)luminosity and surface temperature
C)distance and luminosity
D)distance and surface temperature
E)distance and color

Question 60

The star's color index is a quick way of determining its:

A)density.
B)luminosity.
C)mass.
D)temperature.
E)composition.

Question 61

In what range of masses are most stars found?

A).1 to 2 solar masses
B)1 to 3 solar masses
C).1 to 100 solar masses
D).01 to 100 solar masses
E)Stars can have any mass.

Question 62

In a visual binary system with circular orbits, if in 20 years the two stars' position angleshave shifted by 30 degrees, the pair's period must be:

A)60 years.
B)90 years.
C)120 years.
D)240 years.
E)360 years.

Question 63

In eclipsing binaries, in contrast to spectroscopic binaries, we can also determine a star's:

A)temperature.
B)color.
C)speed.
D)shape.
E)radius.

Question 64

In the H-R diagram, the bright blue-white stars that dominate the naked eye sky lie to the:

A)top left.
B)top right.
C)middle of the main sequence.
D)top center.
E)bottom left.

Question 65

Eclipsing binaries are less common than spectroscopic binaries because:

A)their orbital planes must be nearly edge on from our perspective.
B)their orbital planes must be nearly face on from our perspective.
C)both stars must have the same mass.
D)both stars must have the same diameter.
E)both stars must be spectral type O or B.

Question 66

On the H-R diagram, red supergiants like Betelguese lie:

A)at the bottom left.
B)at the bottom right.
C)at the top left.
D)at the top right.
E)They can't be plotted, for they are not main sequence.

Question 67

In a spectroscopic binary system, the star showing the larger blueshift is:

A)cooler and receding the fastest.
B)less massive of the pair and receding slower.
C)more massive and approaching us.
D)less massive and approaching us at this moment.
E)hotter and receding faster.

Question 68

On the H-R diagram, white dwarfs like Sirius B and Procyon B lie:

A)at the top left.
B)at the top right.
C)close to the Sun, near the center.
D)at the lower left.
E)at the lower right.

Question 69

For a star of 10 solar masses, its main sequence life span will be:

A)ten times longer than our Sun's.
B)about the same as the Sun's.
C)only a tenth of the Sun's.
D)about a hundred times less than the Sun's.
E)only 1/1000th of the Sun.

Question 70

Having nothing to do with trigonometry, ________ parallaxes use the width of absorptionlines to estimate the star's luminosity and size and distance.

A)bolometric
B)photometric
C)spectroscopic
D)holographic
E)videometric

Question 71

In a spectroscopic binary, if a pair shows a combined set of lines tonight, but a maximumsplit two nights later, its orbital period must be:

A)one day.
B)two days.
C)four days.
D)eight days.
E)twelve days.

Question 72

What is the typical main sequence lifetime of a G-type star?

A)10 million years
B)100 million years
C)1 billion years
D)10 billion years
E)100 billion years

Question 73

High mass stars account for most of the ________ in large regions of star formation, such asgalaxies.

A)mass
B)stars
C)planetary nebulae
D)light

Question 74

In general, the narrower the spectral line of a star:

A)the hotter the star is.
B)the bigger the star is.
C)the denser the star is.
D)the smaller the star is.
E)the cooler the star is.

Question 75

How might the most common occurring stars be described, based on our stellarneighborhood?

A)white dwarfs
B)K giants
C)G main sequence
D)A main sequence
E)M main sequence

Question 76

What is the typical main sequence lifetime of an M-type star?

A)one million years
B)ten million years
C)one billion years
D)ten billion years
E)a trillion years

Question 77

Which type of binary can have their sizes measured directly by photometry?

A)virtual
B)visual
C)eclipsing
D)spectroscopic
E)astrometric

Question 78

What is the typical main sequence lifetime of a B-type star?

A)less than a million years
B)20 million years
C)100 million years
D)1 billion years
E)10 billion years

Question 79

Upon what data do measurements of sizes of eclipsing binaries depend?

A)their orbital periods and separations
B)their masses and luminosities
C)their Doppler shifts and durations of stages of their eclipses
D)their temperatures and speeds
E)their temperatures and masses

Question 80

What is the single most important characteristic in determining the course of a star'sevolution?

A)density
B)absolute brightness
C)distance
D)surface temperature
E)mass