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

Question 1

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

Answer 1

True

Question 2

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

Answer 2

True

Question 3

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

Answer 3

True

Question 4

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

Question 5

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

Question 6

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

Question 7

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

Question 8

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

Question 9

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

Question 10

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

Question 11

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

Question 12

For luminosity classification,fat stars have skinny spectral lines.

Question 13

A type B9 star is hotter than a type A0.

Question 14

The Sun's complete classification is G2V.

Question 15

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

Question 16

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

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

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

Question 20

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

Question 21

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 22

What is the absolute magnitude of our Sun?

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

Question 23

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 24

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

A) 0.2".
B) 0.5".
C) 0.02".
D) 0.002".
E) 0.005".

Question 25

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

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

Question 26

At the distance of Jupiter (6 times further away from the Sun than Earth)the amount of sunlight received per square centimeter 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 27

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 28

Which of the following best describes the size and distance relationship of our Sun and the nearest 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

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 30

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 31

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 32

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 33

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

A) 0.1 parsec
B) 0.2 parsec
C) 0.5 parsec
D) 5 parsecs
E) 50 parsecs

Question 34

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

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

Question 35

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 36

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 37

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 38

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 39

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

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

Question 40

A star of ten solar masses would probably stay stable on the main sequence only about 1/1000th as long as our Sun.

Question 41

Star A and star B both have an apparent magnitude of 7.0,but star A is at a distance of 15 pc and 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 star A.
D) Star A and star B appear to have the same brightness, but actually star A is brighter than star B.
E) It is impossible to determine how bright these stars are or appear to be relative to one another, given the information above.

Question 42

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 43

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 44

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

A) 0.5 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 45

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 46

Two red stars have surface temperatures of 3000 K,but Star A's luminosity is about 5% of the Sun's and Star B's luminosity is about 32,000 times the luminosity of the Sun.How much bigger 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 47

Star A and star B both have an absolute magnitude of 2.0,but star A has an apparent magnitude 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 star A.
D) Star A and star B appear to have the same brightness, but actually star A is brighter than star B.
E) It is impossible to determine how bright these stars are or appear to be relative to one another, given the information above.

Question 48

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 49

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

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

Question 50

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

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

Question 51

Star A and star B both have an apparent magnitude of 4.0,but star A has an absolute magnitude 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 star A.
D) Star A and star B appear to have the same brightness, but actually star A is brighter than star B.
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

On the H-R diagram,white dwarfs lie 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 53

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

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

Question 54

Star A is a main sequence star of spectral type F2 and star B is a white dwarf of spectral type B4.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 55

The most famous G type star is:

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

Question 56

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 57

Star A and star B both have an absolute magnitude of 2.0,but star A is at a distance of 50 pc and 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 star A.
D) Star A and star B appear to have the same brightness, but actually star A is brighter than star B.
E) It is impossible to determine how bright these stars are or appear to be relative to one another, given the information above.

Question 58

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 59

Star A has an absolute magnitude of 2.5 and star B has an apparent magnitude of 2.5,but star A 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 star A.
D) Star A and star B appear to have the same brightness, but actually star A is brighter than star B.
E) It is impossible to determine how bright these stars are or appear to be relative to one another, given the information above.

Question 60

Star A is a main sequence star of spectral type G5 and star B is a red giant of spectral type K2.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 61

In a spectroscopic binary system,the star showing the larger blue shift 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 62

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

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

Question 63

The ________ magnitude of a star depends directly upon its luminosity and distance.

Question 64

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 65

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 66

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 67

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 68

If two stars are the same size and one is twice the temperature of the other,how much more luminous is the hotter one?

Question 69

In a visual binary system with circular orbits,if in 20 years the two stars' position angles have 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 70

Capella is the same temperature as our Sun,but about ten times the Sun's diameter; it must be about ________ times as luminous as our star.

Question 71

From hottest to coolest,the seven letters for the star types are ________.

Question 72

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 73

In what range of masses are most stars found?

A) 0.1 to 2 solar masses
B) 1 to 3 solar masses
C) 0.1 to 100 solar masses
D) 0.01 to 100 solar masses
E) Stars can have any mass.

Question 74

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

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

Question 75

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

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

Question 76

A star with a parallax of 1 second of arc is at a distance of ________ by definition.

Question 77

On the H-R diagram,most bright naked eye stars would lie at the ________.

Question 78

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 79

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 80

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

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