Astronomy Test 3
If the stars Betelgeuse and Rigel each have the same luminosity, but the temperature of Betelgeuse is lower than Rigel, which star has the greater surface area? a. Betelgeuse b. Rigel c. same size d. not enough info
A
The stars Antares and Mima each have the same luminosity. Antares is cooler than Mima. Which star is larger? a. Antares b. Mima c. both stars are same size d. not enough info
A
Which method could detect a planet in an orbit that is face-on to the Earth? a. astrometric method b. transits method c. Doppler method
A
Which of these stars has the coolest surface temperature? a. an A star b. an F star c. a K star
C
A star is measured to have a parallax angle of 10 arc seconds. How far way is it? a. .1 parsecs b. 1 parsec c. 10 parsecs d. 100 parsecs
a
According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples? a. apparent brightness will decrease by factor of 9 b. decrease by factor of 3 c. increase by a factor of 9 d. increase by factor of 3
a
If you observed the redshifts of galaxies at a given distance to be twice as large as they are now, then you would determine a value for Hubble's constant that is... a. 2x as large as its current value b. equal to its current value c. 1/2 current value
a
In general, which type of planet would you expect to cause the largest Doppler shift in the spectrum of its star? a. massive planet close to its star b. massive planet far from its star c. low-mass planet far from its star d. low-mass planet close to its star
a
On an H-R diagram, stellar masses... a. can be estimated for main sequence stars but not for other types of stars b. are impossible to determine c. increase from upper left to lower right d. are greatest in the lower left and least in the upper right
a
On the Hertzsprung-Russell diagram, where are small hot stars located? a. lower left b. upper left c. lower right d. upper right e. along main sequence
a
Rigel is much more luminous than Sirius B. Rigel and Sirius B have the same temperature. Which star has greater surface area? a. Rigel b. Sirius B c. same surface area d. not enough info
a
The Doppler technique only provides a measure of the minimum mass of a planet because... a. only the motion of star toward the observer is measured, not the full motion. b. we do not know the exact composition of the planet. c. we do not have the technology to make a direct image of a planet yet d. without a transit observation, the size and therefore density of the planet is unknown e. only a small part of the planet's motion is measured
a
The age of the universe is related to the slope of the graph of Hubble's law, and current data put the age of the universe at about 14 billion years. Suppose that future observations showed that the slope of Hubble's law on the graph is actually steeper than that shown. In that case, the age of the universe would be _________ than 14 billion years because the universe is expanding ______ than current data suggest. (Each choice gives words to fill in the two blanks, separated by a slash.) a. younger/more rapidly b. younger/more slowly c. older/more rapidly d. older/more slowly
a
The axis on a HR diagram represent... a. luminosity and surface temperature b. mass and radius c. mass and luminosity d. luminosity and apparent brightness
a
The disk component of a spiral galaxy includes which of the following parts? a. spiral arms b. globular clusters c. bulge d. halo e. all of the above
a
The graph shows that galaxies with high speeds as measured from earth are.... a. moving away from earth and are farther from earth than galaxies with lower speeds b. moving toward earth and are farther from earth than galaxies with lower speeds c. moving away from earth and are closer to earth than galaxies with lower speeds d. moving toward earth and are closer to earth than galaxies with lower speeds
a
The transit method allows us in principle to find planets around __________. a. only a small fraction of stars that have planets b. only stars of same mass and size as our sun c. only stars located within about 100 ly of earth d. all stars that have planets of any kind
a
The two axes on the HR diagram can be: a. luminosity and temp b. apparent magnitude and absolute magnitude c. radius and main sequence d. radius and luminosity e. spectral type and temp
a
We can always determine the recession velocity of a galaxy (at least in principle) from its redshift. But before we can use Hubble's law, we must first calibrate it by __________. a. measuring the distances to many distant galaxies with standard candle technique b. using Hubble's law to estimate the distances of many galaxies c. measuring the distances to many distant galaxies with parallax d. determining age of the universe
a
What is a common trait of all main sequence stars? a. generate energy through hydrogen fusion in their core b. all spectral type G c. are in final stage of their lives d. all have approximately the same mass
a
What is the cause of stellar parallax? a. earth's orbit around the sun b. varying speed of earth in its orbit around the sun c. gradual motion of stars in the local solar neighborhood d. gradual change in the patterns of the constellations over thousands of years
a
Which jovian planet does NOT have rings? a. all the jovian planets have rings b. jupiter c. neptune d. uranus
a
Which of the following is a valid way of demonstrating parallax for yourself? a. hold you hand up in from of your face and close your right and left eyes b. photograph a person running back and forth c. move your hand slowly back and forth d. follow star's movement toward western horizon
a
Which of the following properties can be inferred from the star's orbital period? a. planet's orbital radius b. planet's mass c. both the planet's orbital radius and its mass d. neither the planet's orbital radius nor its mass
a
Which of the following statements about our sun is NOT TRUE? a. sun's diameter is about 5x that of earth b. sun is made mostly of hydrogen and helium c. sun contains more than 99% of all mass in solar system d. sun is a star
a
Which of these stars is the most massive? a. a main-sequence A star b. a main-sequence G star c. a main-sequence M star
a
You observe a star very similar to our own Sun in size and mass. This star moves very slightly back and forth in the sky once every 4 months, and you attribute this motion to the effect of an orbiting planet. What can you conclude about the orbiting planet? a. planet must be closer to the star than earth is to the sun b. not enough information c. planet must be farther form sun than neptune is from sun d. planet must have mass same as jupiter
a
Zeppelin is a main sequence B6 star and Floyd is a main sequence G3 star. Floyd appears brighter in the sky. Which star is farther away from Earth? a. Zeppelin b. Floyd c. same distance d. not enough info
a
Assuming that other planetary systems form in the same way as our solar system formed, where would you expect to find terrestrial planets? a. likely located farther from the planetary system's star than any jovian planets b. likely be located nearer the planetary system's star than any jovian planets c. there is no way to know
b
Compared to a high-luminosity main-sequence star, stars in the upper right of the H-R diagram are... a. hotter and larger b. cooler and larger c. cooler and smaller d. hotter and smaller
b
Compared to spiral galaxies, elliptical galaxies are... a. bluer and rounder b. redder and rounder c. always much smaller d. redder and flattened e. bluer and flattened
b
Compared to terrestrial planets, jovian planets are... a. more massive, higher in average density b. more massive, lower in average density c. less massive, lower in average density d. less massive, higher in average density
b
Consider the planet that causes the stellar motion shown in Plot 2 (be sure you have clicked the "Plot 2" button in the lower window of the animation). What can be said about a different planet orbiting the same star with an orbital period of 500 days? a. planet must be farther from the star b. planet must be closer to the star c. planet must be less massive d. planet must be more massive
b
How do we use velocity curves (obtained from spectroscopy) to show that some extrasolar planets are close to their host stars? a. velocity curve of the extrasolar planet shows periods much longer than a year b. curve of host star shows periods much shorter than a year c. curve of host star shows periods much longer than a year d. curve of extrasolar planet shows periods much shorter than a year
b
How is the lifetime of a star related to its mass? a. more massive stars live slightly longer lives than less massive stars b. more massive stars live much shorter lives than less massive stars c. more massive stars live slightly shorter lives than less massive stars d. more massive stars live much longer lives than less massive stars
b
If the star Alpha Centauri were moved to a distance 10 times farther than it is now, its parallax angle would... a. get larger b. get smaller c. stay the same
b
Imagine that when we looked out into the universe we found that the light from all galaxies was blueshifted (rather than redshifted) and that the light from the most distant galaxies was blueshifted by the greatest amount. Which statement best describes what we would conclude about the motions of galaxies in this case? a. all are moving toward earth, nearby galaxies move faster b. all move towards earth, distant galaxies move faster c. moving away from earth, nearby move faster d. moving away from earth, distant move faster
b
Is it possible to determine the planet's mass from the star's velocity curve? a. yes, by measuring only the change in the star's orbital velocity over the orbit b. yes, by measuring both the star's orbital period and its change in velocity over the orbit c. no, because the star's spectrum cannot tell us about the planet d. yes, by measuring the star's orbital period only
b
Planetary orbits are: a. very eccentric ellipses and in the same plane b. fairly circular and in the same plane c. fairly circular but oriented in every direction
b
Suppose a planet is discovered by the Doppler technique and is then discovered to have transits. In that case, we can determine all the following about the planet except ______________. a. density b. rotation period c. physical size d. orbital period e. precise mass
b
Suppose you are using the Doppler technique to look for planets around another star. What must you do? a. examine single spectrum of the star b. compare many spectra of star c. compare brightness of the star d. examine a single spectra of orbiting planet e. compare many spectra of planet
b
The astrometric technique of planet detection works best for a. large planets around distant stars b. massive planets around nearby stars c. large planets around nearby stars d. planets in edge-on orbits e. massive planets around distant stars
b
The largest terrestrial planet and jovian planet, are: a. venus and jupiter b. earth and jupiter c. earth and saturn
b
The more distant a star, the .... a. faster its parallax occurs b. smaller its parallax angle c. larger its parallax angle d. slow its parallax occurs
b
The star Peter has an absolute magnitude of +8.0 and belongs to spectral type M. The star Lois has an absolute magnitude of -2.0 and belongs to spectral type M. Which star has the largest surface area? a. Peter b. Lois c. same surface area d. not enough info
b
Using a magical wand, I have instantaneously moved the star called Proxima Centauri, which has 0.00006 times the luminosity of the Sun, twice as far away as its original distance. It now appears... a. 2x as dim b. 4x dimmer c. 2x as bright d. same as before
b
What must we measure directly so that we can infer a star's surface temperature? a. parallax angle b. spectral type c. apparent brightness d. mass
b
Which of the following is not a characteristic of jovian planets? a. they all have many moons b. have higher density c. larger than terrestrial d. farther from sun and farther apart e. have deep atmospheres
b
Which of the following is not a type of binary star system? a. eclipsing binary b. parallax binary c. spectroscopic binary d. visual binary
b
Which of the following three kinds of objects resides closer to the Sun on average? a. comets b. asteroids c. jovian planets
b
Which one of the following can the transit method tell us about a planet? a. its mass b. its size c. the eccentricity of its orbit
b
Based on what you have learned, which of the following best describes the meaning of Hubble's constant (H0 )? a. describes total mass of expanding universe b. describes expansion rate, higher values mean less rapid expansion c. describes expansion rate, higher values mean more rapid expansion d. describes distances at which galaxies are located in an expanding universe
c
By looking at the graph, what can we say about the galaxies that have the lowest speeds? a. moving away from earth and are farther from earth than galaxies with high speeds b. moving toward earth and are farther from earth than galaxies with high speeds c. moving away from earth and are closer to earth than galaxies with high speeds d. moving toward earth and are closer to earth than galaxies with high speeds
c
If star A is closer to us than star B, then Star A's parallax angle is... a. smaller than that of Star B b. fewer parsecs than that of Star B c. larger than that of Star B d. hotter than that of Star B
c
Imagine that you are viewing a star that has an apparent magnitude of 0.2 and is located about 5 parsecs away from us. Which of the following is most likely the star's absolute magnitude? a. -4.8 b. .2 c. .3
c
On the Hertzsprung-Russell diagram, where are small cool stars located? a. lower left b. upper left c. lower right d. upper right e. along main sequence
c
Star X has an apparent magnitude of 1.0 and an absolute magnitude of 1.0. If the distance between the Earth and star were increased, the apparent magnitude number would ____ and the absolute magnitude number would _____ a. Increase -- decrease b. Decrease -- increase c. Increase -- not change d. Not change -- increase e. Decrease -- not change
c
Suppose that a star had a parallax angle of exactly 1 arc second. Approximately how far away would it be, in light-years? a. 1 light year b. 2.1 ly c. 3.3 ly d. 8.7 ly
c
Very few of the known extrasolar planets have sizes as small as Earth. The most likely reason for this fact is that ________. a. small planets are extremely rare b. small planets probably orbit too far from their stars to have been detected yet c. small planets are more difficult to detect than larger planets d. small planets are usually made of materials that cannot be detected
c
What do we need to measure in order to determine a star's luminosity? a. apparent brightness and mass b. apparent brightness and temperature c. apparent brightness and distance
c
What method has detected the most extrasolar planets (or candidates) so far? a. Hubble images b. Doppler method c. transit method
c
What would your estimate be for the age of the universe if you measured Hubble's constant to be 11 kilometers per second per million light-years? a. 7 billion b. 14 billion c. 28 billion
c
When would you receive the greatest amount of light from a binary star system consisting of an M5 Red Giant and an M5 main sequence star? a. when red giant is in front of main sequence b. when main sequence is in front of red giant c. same amount of light
c
Which of these stars has the largest radius? a. Supergiant A star b. Giant K star c. Supergiant M star
c
Which of theses stars has the longest lifetime? a. main sequence A star b. main sequence G star c. main sequence M star
c
Why do virtually all the galaxies in the universe appear to be moving away from our own? a. we are located near Big Bang happening b. located near center of universe c. observers in al galaxies observe a similar phenomenon
c
Scientists investigating _____ study how the distribution of galaxies changes with time
cosmology
Approximately what is the parallax angle of a star that is 20 light years away? a. .0072 arcsecond b. 4.5 x 10-5 arcsecond c. .33 arcsecond d. .16 arcsecond
d
Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do? a. determines both the star's distance and luminosity from its apparent brightness b. calculate the star's surface temperature if we know either its luminosity or its distance c. determine the distance to the star from its apparent brightness d. calculate the star's luminosity if we know its distance, or calculate its distance if we know its luminosity
d
Before we can use parallax to measure the distance to a nearby star, we first need to know... a. sun's mass b. distance to the nearest star besides the sun c. month in which the star is observed d. earth-sun distance
d
Compared to a low-luminosity main-sequence star, stars in the lower left of the H-R diagram are... a. hotter and larger b. cooler and larger c. cooler and smaller d. hotter and smaller
d
Compared to a main-sequence star with a short lifetime, a main-sequence star with a long lifetime is... a. more luminous, hotter, larger, and more massive b. more luminous, hotter, smaller, and less massive c. less luminous, cooler, larger, and more massive d. less luminous, cooler, smaller, and less massive
d
From hottest to coolest, the order of the spectral types of stars is... a. OBAGFKM b. OMKGFBA c. ABCDEFG d. OBAFGKM e. ABFGKMO
d
From the viewpoint of an alien astronomer, how does Jupiter affect observations of our Sun? a. makes sun appear dimmer when viewed with infrared light b. makes sun periodically appear to get dimmer and brighter c. causes sun to move in a small eclipse in the sky, with the same ellipse repeated every night d. causes the sun to move in a small ellipse with orbital period of about 12 years
d
From which binary star system (made up of two main sequence stars) described below would an Earth observer detect the least amount of total light? a. When a star with an absolute magnitude of 5.0 is in front of a star with an absolute magnitude of -2.0. b. When a star with an absolute magnitude of 1.0 is behind a star with an absolute magnitude of -2.0. c. When a star with an absolute magnitude of 5.0 is behind a star with an absolute magnitude of 1.0. d. When a star with an absolute magnitude of 5.0 is in front of a star with an absolute magnitude of 1.0. e. When a star with an absolute magnitude of 5.0 is behind a star with an absolute magnitude of -2.0.
d
Hubble's law expresses a relationship between... a. Hubble's constant and the recession velocity of a galaxy b. distance from a star from the center of its galaxy and its orbital speed c. recession velocity of a galaxy and the speed at which it is moving away from us d. distance of a galaxy and the speed at which it is moving away from us
d
Suppose that galaxy B is twice as far from Earth as galaxy A. Hubble's law predicts that galaxy B will be moving away from Earth with approximately _____. a. same velocity as galaxy A b. 4x velocity of galaxy A c. 1/2 velocity of galaxy A d. 2x velocity of galaxy A
d
The transit method of planet detection works best for.. a. big planets in face-on orbits w/small stars b. small planets in edge-on orbits w/ big stars c. small planets in face-on orbits w/ big stars d. big planets in edge-on orbits w/ small stars e. earth-like planets in any orbit
d
We found that mass must be inferred for the star described in Part A. However, we can measure a star's mass directly if __________. a. it is unusually high in mass b. we know its spectral type c. near enough to measure its distance with parallax d. it is a member of an eclipsing binary system
d
Which detection techniques can find the planet's orbital distance (assuming we know the mass of the star)? a. only the doppler technique b. only the transit technique c. only the astrometric technique d. all of these techniques
d
Which lists the planets in order of increasing size (radius)? a.Mercury,Earth,Mars,Venus,Jupiter,Saturn,Uranus, Neptune b.Mercury,Venus,Mars,Earth,Neptune,Uranus,Jupiter, Saturn c.Earth,Mercury,Venus,Mars,Saturn,Jupiter,Neptune, Uranus d.Mercury,Mars,Venus,Earth,Neptune,Uranus,Saturn, Jupiter e.Mars,Earth,Mercury,Venus,Saturn,Uranus,Neptune, Jupiter
d
Which of the following will allow you to learn something about a transiting planet's atmospheric composition? a. Calculate the planet's size, and then use size to infer what its atmospheric composition must be. b. Use the Doppler method to study the planet throughout a cycle from one transit to the next. c. Look for slight variations in the time between transits. d. Compare spectra obtained before and during an eclipse.
d
Which planet is approximately halfway between Pluto's orbit and the sun? a. Mars, 4th planet from sun b. Jupiter, 5th planet from sun c. Saturn, 6th planet from sun d. Uranus, 7th planet from sun
d
Why do we say that the Doppler technique gives the planet's "minimum mass"? a. The size of the Doppler shift that we detect depends on knowing the star's mass, which can be very uncertain b. Extrasolar planets are always increasing in mass. c. Doppler measurements are very difficult, producing noisy data that often cause astronomers to underestimate a planet's mass. d. The size of the Doppler shift that we detect depends on whether the planet's orbit is tilted.
d
Why is it so difficult to take pictures of extrasolar planets? a. no telescope is powerful enough b. extrasolar planets give off light at different wavelengths than planets in our solar system c. telescopes are too busy with other projects d. light is overwhelmed by the light from their star
d
You look up at the sky one night and the star Pollux is twice as bright as castor. Which of the following is true? a. pollux is closer than castor b. castor is closer than pollux c. they're the same distance from earth d. not enough info
d
Our sun belongs to the ___ ____ of the milky way galaxy
disk component
Which of the following planets does not have any moons? a. uranus b. mars c. saturn d. neptune e. venus
e
An ____ ____ contains hot, ionized gas but very little cool gas or dust
elliptical galaxy
Stars that are cooler than the Sun yet 100 to 1000 times as luminous as the sun are classified as _____
giants
The type of galaxy known as an ____ ____ was more common in the universe 10 billion years ago
irregular galaxy
Stars are classified on the basis of their spectral type and ____
luminosity class
The ____ is greater for low-mass stars than it is for high-mass stars
main sequence lifetime
Most of the stars near the sun are ____
main sequence stars
Cepheids are examples of _____
pulsating variable stars
The globular cluster M13 belongs to the ____ ____ of the milky way galaxy
spheroidal component
The milky way is an ____ _____
spiral galaxy
The stars known as ____ are the very largest and brightest of all stars
supergiants
_____ are no longer generating energy through nuclear fusion
white dwarfs
