FINAL EXAM ASTRONOMY

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 bottom, horizontal line

The first astronomer who did photometry in a systematic way (even though they did not have a telescope) was

Hipparchus

On a H-R diagram, where would we find stars that are cool and dim?

Lower right

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

The Sun is so hot that all of the material in it is in the form of an ionized gas, called a(n):

Plasma

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

The main source of the Sun's energy is:

Thermonuclear fusion of hydrogen to helium

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

White dwarf

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

a brown 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

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

After the core of a massive star becomes a neutron star, the rest of the star's material

explodes outward as a supernova

Astronomers have discovered a planet orbiting Proxima Centauri, the star closest to the Sun. This is a star of spectral type M, with 12% the mass of the Sun and 15% the size of the Sun. The habitable zone around this star would be

much closer to the star than the Sun's

In the , photons take approximately between 100,000 to 1,000,000 years to "random walk" towards the surface of the Sun.

radiative zone

Herbig-Haro (HH) object

where a jet from a star in the process of being born collides with (and lights up) a nearby cloud of interstellar matter

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

B

Current evidence indicates that the universe was born out of a hot, dense, violent state of matter and energy called the

Big Bang

Which color star is likely to be the hottest?

Blue

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

Which of the following can astronomers NOT learn from studying the spectrum of a star?

Cant fool me all above.

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

the study of the structure and evolution of the universe as a whole

Cosmology

Which nebula was observed as an exploding star, first seen nearly 1000 years ago by Chinese astronomers?

Crab Nebula

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

Dark Matter

is hypothesized to make up around 70% of the universe, permeate all of space, and cause the accelerated expansion of the universe.

Dark energy

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?

Doppler shift

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

Doppler shift method

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

What incident in a massive star's life sets off (begins) the very quick chain of events that leads to a supernova explosion?

Fusion of iron

Which of the following spacecraft is NOT leaving the solar system?

Galileo

In the context of nuclear reactions in the Sun, protons collide directly with other protons in the proton-proton chain to form:

Helium Nuclei

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

Hertzsprung.

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

The two most abundant elements in the Sun, with the most abundant given first, are

Hydrogen and Helium

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

When energy is first produced by fusion deep in the core of the star, that energy moves outward mostly by what process?

Radiation

What kind of telescope did Jocelyn Bell use to discover pulsars in 1968?

Radio

Which of the following is the largest (in diameter)?

Red Giant

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 technique allows astronomers to detect exoplanets by the planet dimming the star's light as it passes in front of the star?

Transit method

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

Vesto Slipher

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

The Orion Nebula is

a large cloud of gas and dust illuminated by the light of newly formed stars within it

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?

a sensitive infra-red telescope

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

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

an audio and video record

Which of the following types of galaxies have their light dominated by older reddish stars?

astronomers have a solid understanding of what it is made of.

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

The proton-proton chain

is a three step process which converts some mass to energy as helium nuclei are formed.

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

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

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

smaller in diameter

Elements heavier than iron can be created during:

supernova explosion

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

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

Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call:

the main sequence

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

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

According to astronomers, which of the following places in the outer parts of our solar system might be a reasonable place for life to exist?

under the ice of Jupiter's moon Europa