ASTRO160 - Final Exam SG

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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

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 types of star is the hottest (has the hottest surface temperature)?

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

Working with the 2.5-meter telescope, was able to resolve individual stars in several of the brighter spiral-shaped nebulae, including M31, the great spiral in Andromeda

Edwin Hubble

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 of the following spacecraft is NOT leaving the solar system?

Galileo

developed a technique to use cepheid variables stars to estimate distances in the universe.

Henrietta Leavitt

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

Which of the following is NOT a possible end point in stellar evolution?

Main sequence star

Exoplanets are

Planets around stars other than the Sun

The astrophysicist who first calculated the highest mass that a dying star can have and still be a white dwarf was

S. Chandrasekhar

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

The first astronomer to show that spiral nebulae (today called spiral galaxies) have large Doppler shifts was

Vesto Slipher

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

Which of the following is a "failed star", an object with too little mass to qualify as a star?

a brown dwarf

When the mass of a star's core is greater than 1.4 times the mass of the Sun, degenerate electrons can't keep it stable as a white dwarf. Instead, it becomes:

a neutron star

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

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

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

A star that is quite hot and has a very small radius compared to most stars is called

a white dwarf

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 alien beings found one of the Voyager spacecraft in a million years, what would they find aboard?

an audio and video record

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)

Planets in the habitable zone of their stars:

are at a temperature where water can exist as a liquid

Which of the following statements about dark matter is FALSE:

astronomers have a pretty good idea what the dark matter is made of

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

Why can a star with a mass like our Sun not fuse (produce) further elements beyond carbon and oxygen?

because they just cannot get hot enough for the fusion of heavier nuclei

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

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

At an astronomical conference, an astronomer gives a report on a star that interests astronomers because of hints that it may have a planet around it. In his report the astronomer gives the average speed with which this star is moving away from the Sun. How did the astronomer measure this speed?

by looking at the Doppler shift in the lines of the star's spectrum

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

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

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

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 electromagnetic 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

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

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

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

nine times fainter

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

Astronomers call a ball of matter that is contracting to become a star

protostar

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

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

Which of the following bolded words in the next sentence is incorrect? Low mass stars around 0.1 solar masses appear to be red, have shorter lifespans, have lower temperatures, and have a smaller radius than a more massive star.

shorter

A white dwarf, compared to a main sequence star with the same mass, would always be:

smaller in diameter

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

Which of the following events in cosmic history is the most recent?

the formation of life on Earth

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

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

The fastest speed at which we might communicate with another technological civilization among the stars (according to our present understanding of science) is

the speed of light

When stars become giants, which of the following does NOT usually happen?

their mass grows significantly as they incorporate planets and interstellar matter near the 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

A star whose temperature is increasing but whose luminosity is roughly constant moves in what direction on the H-R diagram?

to the left

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

When a single star with a mass equal to the Sun dies, it will become a

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

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

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

The first search for radio messages from extra-terrestrial civilizations was called

Project Ozma

Which of the following sequences below correctly describes the evolution of the Sun from young to old?

Protostar, main-sequence, red giant, white dwarf

Protostars with mass equal to or less then the mass of the Sun are called

T Tauri Stars

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.

Non-luminous material whose gravitational influence can explain the high rotational velocities of galaxies is called .

Dark Matter

Which technique allows astronomers to detect exoplanets by causing the star's position to "wobble"?

Doppler shift method

Who was the astronomer who is the "H" in H-R diagram?

Hertzsprung

Which of the following types of stars will spend the longest time (the greatest number of years) on the main sequence?

K

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

A star with an initial mass of under 8 solar masses will become a

White Dwarf


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