Final Astronomy Exam
Factoring in everything we currently know about the history of the universe, our best estimate for the age of the universe is
13.8 billion years
We receive a radio message from a civilization around a star about 40 lightyears from Earth? If we reply right away, how long will it be between the time THEY sent the message and the time they receive our reply?
80 years
According to our textbook, roughly what percent of the mass and energy contents of the universe is made up of dark matter plus dark energy?
95 percent
Two stars have the same luminosity, but star B is three times farther away from us than star A. Compared to star A, star B will look
9x fainter
The first astronomer to show that spiral nebulae (today called spiral galaxies) have large Doppler shifts was
Vesto Slipher
A star with an initial mass of under 8 solar masses will become a
White Dwarf
Some objects in space just don't have what it takes to be a star (just like many hopefuls in Hollywood don't.) Which of the following is a "failed star", an object with too little mass to qualify as a star?
a brown dwarf
The Orion Nebula is
a large cloud of gas and dust illuminated by the light of newly formed stars within it
Which of the following is, to the best of our knowledge, in the habitable zone of its star:
a planet about 1.05 AU from a G-type main sequence star
After the Sun becomes a red giant, what will be the next phase in its evolution?
a planetary nebula
Astronomers call a ball of matter that is contracting to become a star
a protostar
If you want to check on what conditions were like in the universe a few hundred thousand years after the Big Bang, what sort of instrument would it be best to use:
a satellite with infrared and microwave telescopes on board
A star moving toward the Sun will show:
a shift in the spectral lines toward the blue end (as compared to the laboratory positions of these lines)
Which of these stars will take the SHORTEST time to go from the earliest protostar stage to the main sequence?
a star ten times the mass of our Sun
Which of the following looks the brightest in the sky?
a star with apparent magnitude -1
Elements heavier than iron can be created during:
a supernova explosion
Which of the following stages will our own Sun go through in the future:
all of these answers are correct; - expanding to become a red giant - spending a long time on the main sequence - giving off a planetary nebula - eventually fusing helium into carbon
The event in the life of a star that begins its expansion into a giant is
almost all the hydrogen in its core that was hot enough for fusion has been turned into helium
In an H-R diagram, where can you see the spectral type of a star (whether it is an O type star or a G type star, for example)?
along the bottom (the horizontal axis)
One of your good friends who is on a diet asks you to point out the stars with the smallest mass on an H-R diagram that you are studying. Where are you sure to find the stars with the lowest mass on any H-R diagram?
among the stars at the bottom right of the main sequence
If an astronomer wants to find and identify as many stars as possible in a star cluster that has recently formed near the surface of a giant molecular cloud (such as the Trapezium cluster in the Orion Nebula), what instrument would be best for her to use?
an infra-red telescope (and camera)
The astronomer who, at the turn of the century, measured the spectra of hundreds of thousands of stars, leaving a catalog that astronomers used for the rest of the century, was:
annie cannon
Which of the following statements about dark matter is FALSE:
astronomers have a pretty good idea what the dark matter is made of
Really massive stars differ from stars with masses like the Sun in that they
can fuse elements beyond carbon and oxygen in their hot central regions
Today, we believe that only a small number of elements were actually formed during the Big Bang. Which of the following was NOT one of these:
carbon
After the core of a massive star becomes a neutron star, the rest of the star's material
explodes outward as a supernova
Astronomers identify the main sequence on the H-R diagram with what activity in the course of a star's life?
fusing hydrogen into helium in their cores
If stars with masses like our Sun's cannot make elements heavier than oxygen, where are heavier elements like silicon produced in the universe?
heavier elements are made in the cores of significantly more massive stars than the Sun, which can get hotter in the middle
The triple alpha reaction converts _________ into __________ .
helium, carbon
When an astronomer rambles on and on about the luminosity of a star she is studying, she is talking about:
how much energy the star gives off each second
If you wanted to find a type of atom in your little finger that has been in its present form (been the same element) since the beginning of the universe, which element should you look for?
hydrogen
Studies of the spectra of stars have revealed that the element that makes up the majority of the stars (75% by mass) is
hydrogen
If you want to find stars that are just being born, where are the best places to search?
in giant molecular clouds
Currently, the furthest observable galaxies are moving so fast away from us that the light from their stars has redshifted so much that they are more observable in the part of the ___ spectrum
infrared
Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500 K). How can this be?
it must be quite large in size
How long a main sequence star remains on the main sequence in the H-R diagram depends most strongly on
its mass
Our own Galaxy and the Andromeda galaxy are typical,
large spiral galaxies
On a H-R diagram, where would we find white dwarfs?
lower left
On a H-R diagram, where would we find stars that are cool and dim?
lower right
Which of the following statements about the main sequence stage in the life of a star is FALSE?
main sequence stars are rare in the Galaxy, so we are lucky to be living around one
When a star settles down to a stable existence as a main-sequence star, what characteristics determines where on the main sequence in an H-R diagram the star will fall?
mass
A team of astronomers discovers one of the most massive stars ever found. If this star is just settling down in that stage of its life where it will be peacefully converting hydrogen to helium in its core, where will we find it on the H-R diagram?
near the very top of the main sequence, in the upper left
Which of the following is the smallest?
neutron star
Where on the H-R Diagram would we find stars that look red when seen through a telescope?
only on the right side of the diagram and never on the left
The first search for radio messages from extra-terrestrial civilizations was called
project ozma
What kind of telescope did Jocelyn Bell use to discover pulsars in 1968?
radio
Which band of the electromagnetic spectrum do astronomers suggest is likely to be the best (cheap, little competition from nature, penetrates atmospheres) for communication between civilizations around different stars?
radio waves
Which of the following is the largest (in diameter)?
red giant
Why is it easier for red giants to lose mass than main sequence stars?
red giants are so big, the gravity at their surface (that holds material to the star) is less
The majority of observed galaxies are moving away from us. This means the light from these galaxies is
red shifting
The astrophysicist who first calculated the highest mass that a dying star can have and still be a white dwarf was
s. chandrasekhar
In recent decades, astronomers discovered stars even cooler than the traditional spectral type M stars recently. Astronomers gave these cool stars a new spectral type, L. If you wanted to go out and find more such type L stars, what kind of instrument would it be smart to use?
sensitive infra-red telescope
A white dwarf, compared to a main sequence star with the same mass, would always be:
smaller in diameter
The fastest speed at which we might communicate with another technological civilization among the stars
speed of light
An astronomer whose secret hobby is riding merry-go-rounds has dedicated his career to finding the stars that rotate the most rapidly. But the stars are all very far away, so none of them can be seen to spin even when he looks through the largest telescopes. How then can he identify the stars that rotate rapidly?
stars that rotate have much wider lines in their spectra than stars that do not
An H-R Diagram plots the luminosity of stars against their:
surface temperature
The new instrument that made it possible for Edwin Hubble to demonstrate the existence of other galaxies in the early 1920's was:
the 100-inch reflector on Mount Wilson
Which of the following is pretty good evidence that the universe began with a Big Bang?
the 2.7-degree cosmic microwave background radiation
When a star first begins the long path toward becoming a red giant, a layer of hydrogen around the core begins to undergo fusion. If this layer was too cold to do fusion throughout the main sequence stage, why is it suddenly warm enough?
the core is collapsing under its own weight and heating up from the compression; this heats the next layer up
Edwin Hubble was able to show that (with the exception of our nearest neighbors) the farther a galaxy is from us, the
the faster it is moving away from us
What incident in a massive star's life sets off (begins) the very quick chain of events that leads to a supernova explosion?
the fusion of iron
When they talk about the Copernican principle, philosophers and astronomers mean that:
the idea that there is nothing special about our place in the universe
Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call:
the main sequence
The Drake Equation allows astronomers to estimate
the number of civilizations out among the stars with which we might communicate
Many names used by astronomers are misleading or outdated. A good example is the term planetary nebula, which astronomers use to refer to:
the shell let go by a dying low-mass star
Edwin Hubble developed a classification scheme for galaxies. By what characteristic did he classify galaxies?
their shape
Among irregular galaxies, what makes the Large and Small Magellanic Cloud especially useful for astronomers?
they are (for galaxies) very close to us, so they are easy to study
The Andromeda Galaxy (our nearest spiral neighbor) has spectral lines that show a blue shift. From this we may conclude that:
this particular nearby galaxy is moving toward us
When the core of a star reaches a temperature of about 100 million degrees (K), something new happens in the core. What is this new event?
three helium nuclei begin fusing carbon (element number 6)
When the outer layers of a star like the Sun expand, and it becomes a giant, which way does it move on the H-R diagram?
toward the upper right
On a H-R diagram, where on the main sequence would we find stars that have the greatest mass?
upper left
Astronomers identify the "birth" of a real star (as opposed to the activities of a protostar) with what activity in the star?
when nuclear fusion reactions begin inside its core
A Herbig-Haro (HH) object is
where a jet from a star in the process of being born collides with (and lights up) a nearby cloud of interstellar matter
From a scientific perspective, which of the following statements about life elsewhere in the universe is best supported by current evidence?
while we have evidence of the building blocks of life elsewhere in the universe, we have no definite evidence about life around other stars at this time
A star that is quite hot and has a very small radius compared to most stars is called
white dwarf
When a single star with a mass equal to the Sun dies, it will become a
white dwarf
Which of the following stages can only occur in the life of a low-mass star (whose final mass is less than 1.4 times the mass of the Sun)?
white dwarf
Which of the following can astronomers NOT learn from studying the spectrum of a star?
you can't fool me, all of the answers can be learned from studying the spectrum
What does the abbreviation ZAMS stand for
zero-mage main sequence
Which of the following types of star is the hottest (has the hottest surface temperature)?
B
Which of the following types of stars will spend the shortest time (the least number of years) on the main sequence?
B
The Milky Way is thought to be which type of galaxy from the class notes/lecture?
Barred Spiral
Current evidence indicates that the universe was born out of a hot, dense, violent state of matter and energy called the
Big Bang
The maximum mass that a star can end its life with and still become a white dwarf, which is about 1.4 MSun , is called the .
Chandrasekhar limit
is the study of the structure and evolution of the universe as a whole.
Cosmology
is hypothesized to make up around 70% of the universe, permeate all of space, and cause the accelerated expansion of the universe.
Dark Energy
The astronomer took data with his 2.5 meter (100 inch) telescope on Mount Wilson to analyze nebulae which would later be known as galaxies.
Edwin Hubble, reflecting
Which of the following types of galaxies have their light dominated by older reddish stars?
Elliptical
Which technique allows astronomers to detect exoplanets by the planet dimming the star's light as it passes in front of the star?
Transit method
Which of the following spacecraft is NOT leaving the solar system?
Galileo
What does the Fermi Paradox say?
Given all the time since the Big Bang and all the stars, why has some form of intelligent life in the Galaxy not established a network throughout the Galaxy and visited us?
developed a technique to use cepheid variables stars to estimate distance in the universe.
Henrietta Leavitt
Who was the astronomer who is the "H" in H-R diagram?
Hertzsprung
The first astronomer who did photometry in a systematic way (even though they did not have a telescope) was
Hipparchus
Which of the following types of stars will spend the longest time (the greatest number of years) on the main sequence?
K
The ____ Space Telescope monitored the brightness of approximately 150,000 main sequence stars in a fixed field of view.
Kepler
One reason that some scientists think that there may be life under the ice-crust of Jupiter's moon Europa is that:
Life has been found on Earth, at the bottom of the ocean, deriving its energy not from sun-light but from hot mineral-laden vents coming from deeper inside our planet; something similar could happen at the bottom of the ocean on Europa
Which of the following types of star is the coolest (has the lowest surface temperature)?
M
A star with an initial mass of between 8 to 40 solar masses will become a
Neutron Star
Biologists tell us that life on Earth took billions of years to evolve into astronomy students and other examples of intelligent life. If we want to search for planets with intelligent life-forms that evolved over the same period of time that we did, what sorts of stars should we not bother searching around?
O and B type stars
Which of the following has the stellar spectral classes correctly ordered from hottest to coolest?
OBAFGKM
The two scientists who first discovered the cosmic microwave background radiation were:
Penzias and Wilson
Exoplanets are
Planets around stars other than the Sun
Why was the Kepler mission not able to find planets smaller than Mars, even though it was in space (and had no Earth atmosphere to deal with)?
Such planets make dips in the light of the star that are too small for Kepler to detect
Which of the following is not an abbreviation for a galaxy?
T2
is the variable on the horizontal axis (or x-axis) for the H-R Diagram and is listed from to .
Temperature, high, low
What is nucleosynthesis?
The formation of heavy elements by nuclear fusion processes.
In the model that astronomers have developed for pulsars, why do they suggest that there must be two beams of energy coming from the pulsar?
because neutron star beams come out of the north and south poles of a magnetic field
Why do all stars spend most of their lives on the main sequence?
because the fuel for energy production in this stage of the star's life is hydrogen; and that is an element every star has lots and lots of
Scientists think that the life we have on Earth today originated some time between 3.5 and 3.8 billion years ago. Yet the solar system and the Earth are known to be at least 4.5 billion years old. Which of the following is one reason life as we know it had to wait until 3.5 to 3.8 billion years ago to get going?
before 3.8 billion years ago, the Earth was experiencing a period of heavy bombardment, when giant chunks of rock and ice left over from planet formation kept hitting our planet and making it uninhabitable
A star with an initial mass over 40 solar masses will become a
blackhole
An object whose gravitational field is so strong that light cannot escape is called a
blackhole
Which color star is likely to be the hottest?
blue
One key difference that astronomers use to distinguish between brown dwarfs and high-mass planets is that:
brown dwarfs are able to do deuterium fusion in their cores, while planets can't
One of the most important observations in the history of astronomy was the one by Edwin Hubble that established that there are other galaxies, quite removed from the Milky Way. How did Hubble show this?
by observing a Cepheid variable in a nearby galaxy and using it to get the distance
Non-luminous material whose gravitational influence can explain the high rotational velocities of galaxies is called
dark matter
Astronomers arrange the stars into groups called spectral classes (or types) according to the kinds of lines they find in their spectra. These spectral classes are arranged in order of:
decreasing surface temperature
Which technique allows astronomers to detect exoplanets by causing the star's position to "wobble"?
doppler shift method
Where in space did the expansion of the universe begin?
everywhere at once
