AY-101 University of Alabama Final Exam (Bailin)

The main sequence of star cluster A appears four times brighter than the main sequence star B. Which is true?

Cluster A is 2x closer than cluster B due to the inverse square law

Which if these objects does the Milky Way most resemble?

A fried egg

Where are we in the Milky Way?

In the disk, Spot 2

How do we measure the mass of the black hole at the center of the Milky Way?

Using the orbits of stars in the galactic center

Which is true about the orbits of stars in the halo?

Many are random but some move in streams together

What is at the very center of the Milky Way Galaxy?

A black hole, 4 million times the mass of the sun

On average, the sun moves around the center of the Milky Way at 220km/s.. When the Sun is in a spiral arm...

It moves slower than 22km/s because the spiral arm is created by slower-moving stars pilling up in a traffic jam

Could this picture be of a dark matter cloud?

No- dark matter does not show up in images in any way- only its gravitational effect can be seen

Based on what you know, what can you say about the colors of elliptical and spiral galaxies?

Spiral galaxies have both young blue stars and old red stars, but elliptical galaxies only have old red stars, so spiral galaxies are more blue than elliptical ones

If you see a galaxy with a 10^10 solar masses of stars, that is forming stars at a rate of 10^2 solar masses/year long how long could it have been forming stars at this rate?

10^8
much less than that of the age of the universe
forming stars much faster than it used to

Quiescent (red/dead) galaxies would take 10^14 (10,000 times the age of the universe) to form all of their stars at the current rate of star formation. Therefore:

They are forming stars much slower than

Why would you put a telescope in space?

It can detect ultra-violet light, gets above the turbulent atmosphere

Which is not true about black holes?

They are holes in the fabric of space and time

Which if the following phenomena is not a result of close binary stars?

Core collapse supernovae

What happens to a white dwarf if it gets larger than 1.4 solar masses?

Degenerate carbon fusion ignites it and blows it apart as a type of 1a supernovae

Why do star forming molecular clouds mainly emit far infrared light?

In order to form stars, the cloud must be cold, so their thermal emission is infrared

Unlike low-mass main sequence stars, brown dwarfs do not fuse hydrogen to helium in their cores, why?

Their cores never get hot enough to fuse hydrogen, too low mass

Which are more likely to have planets? Planets that formed long ago or planets that formed recently?

Planets that formed recently- the heavy elements that make up rocky/icy cores had to be created by earlier stars

Which if the following is a reason which we thinks that the Milky Way is a spiral galaxy?

Because we have mapped out the distances within the Milky Way and found that they lie in spirals

Star formation occurs in only high density gas. Where in the galaxy do you think you will see star formation?

In the disk, in spiral arms

What's Quasar?

Gas in a hot accretion disk around a supermassive black hole at the center of a galaxy that complete;y outshines the entire galaxy

Which of the following is often caused by galaxy interaction/mergers?

Starburst galaxies
Elliptical galaxies
Streams in stellar halos
Active galactic nuclei

Which substances condense outside the frostline of a protoplanetary system?

Rock, ice and metal

When a star like the sun dies, what will it leave behind?

A white dwarf (typical low mass star

Which if the following set of observations would allow you to put a star on a H-R Diagram?

It's spectral type, brightness and parallax angle

Which Object contains 99.8% of the mass of the Solar System?

The sun

Black holes are...

Detectable by x-ray emission from material that has not yet fallen through the event horizon

Can we detect black holes?

Yes- we can see light coming from material that is falling towards the event horizon but hasn't crossed it yet

Which of these could be the progenitor of a black hole?

A 25 sun mass main sequence star

Where would you expect to see a core collapse supernovae?

Mainly in spiral galaxies
News stars that are massive are only in spiral
No new stars in elliptical galaxies

Galaxies are large compared to the distances between them, stars are small compared to the distances between them?

galaxies collide, but the stars within them rarely ever collide

Why is radar important for measuring how far away very distant galaxies are...

Because we can directly measure the distance to the sun...

If a galaxy is receding from us at .1 light years per year and it is now 1.4 billion light years away, how long did it take to get there?

14 Billion years

Which distance method would be most appropriate to measure the distance to a nearby galaxy?

Hubble's Law

If a galaxy is 500 million light years away has a redshift of 10,000 km/s how far away would you expect a galaxy to be if it's redshift is 30,000 km/s?

1.5 billion light years

Which if the following is true about galaxies?

...

Gravity, which causes galaxy mergers, acts faster when objects are denser. When in their lives do galaxies move most often?

Mainly when the Universe was young

Why does the initially smooth universe change into a clumpy universe?

Because of gravitational instability

Which of the following is true about dark energy?

...

In the early universe the matter, anti-matter and photons are in equilibrium. That means...

...

Which observation disproves the following statements? " There was exactly the same amount of matter and anti-matter during the particle Era in the early universe?

The Universe contains mostly matter

Which of these is true about the cosmic microwave background?

light emitted by 3000K in the early universe that has been redshifted 1000x due to the expansion of the universe

What do we call a structured physical object that consumes the energy to maintain and or grow its structure...

life

Why does exponential growth of a population lead to natural selection?

Because the resources required by the population must eventually outstrip the available resources, so individuals need to compete

Why do you think that mars and Europa are more likely to harbor life than the moon and mercury?

Because there is evidence that they have had or have liquid water

What is the habitable zone?

Where you would expect to find liquid water

Antibiotic resistance is and example of...

Evolution

Which if the following ingredients for life are relatively easy to find?

Carbon compounds
Energy sources

Planets around low mass stars are probably not the best places to look for life because...

The habitable zone is so small that it would be very unlikely to find a planet there

If there were intelligent life on a planet around star DB+61 1574, which is 10 light years away, how would they detect it on Earth?

By detecting infrared ozone absorption in our atmosphere

If we observe a galaxy 12.5 billion light years away which if the following is true?

We see a galaxy of young stars, like when you look at old picture you see a young you

If you could see stars during the daytime, the picture shows what part of the sky would look like at noon on a day in July. The Sun is among the stars in the constellation Gemini. When the sun sets later that day near which constellation would you expect the sun to be located?

Gemini

The force most responsible for keeping people, shoes, chairs and pens individually held together is?

Electromagnetic Force

Why does a rocket rise?

Because the exhaust goes down very fast and momentum is conserved

A hot solid like a piece of metal or rock emits light at...?

light at all wavelengths

Does your pencil emit a thermal spectrum?

Yes, it emits a thermal spectrum that consists of mostly infrared light

At the speed of light how long would it take to travel from the Earth to the Sun?

About 8 minutes

In order from smallest to largest...

Solar system, galaxy, universe

Which period was the longest?

The Milky Way existed but the Solar System was not born yet.

Which sentence is logical?

"I hit the ball so hard it landed light years away!"

Why should you be suspicious if someone claims to show you an image of a galaxy 20 billion light years away?

There hasn't been enough time for light to travel to us from that far away.

Which was the longest?

Earth existed with primitive life.

The stars that make up a constellation...

Are in in the same direction from the earth but possibly at different distances.

From which location could you potentially see the most stars if you wait long enough?

The equator/Ecuador

If the sun appear near the bright star Regulus and the galaxy Leo I when it rises from the eastern horizon one morning, then at noon?

The sun, Regulus and Leo I will all be overhead.

Which of the following is not true about Polaris?

It is the brightest star you can see from Tuscaloosa

Which day is longer?

The Solar Day

Is the Earth closer to the sun in the Summer?

No

This years' autumnal equinox is on September 22. How long will the day be?

Exactly 12 hours

Which phases of the moon are caused by the earths shadow?

None of them

Which phases of the moon are caused by the Earth's shadow?

None of them

When the moon is a crescent it is mainly...

up during the day

When does a new moon rise?

At sunrise

Lunar Eclipse

Full Moon

Solar Eclipse

New Moon

If you see the moon in the sky at nine am one day before class, which phase would it be in?

Waning crescent

How would our view of stellar parallax change if we were on Mars?

It would be easier to see because Mars has a bigger orbit.

What is the Copernican Principle

We are not in a special place in the Universe

When does the Earth move fastest around the sun?

January

Is there any relationship between the phase of Venus and the apparent angular size of its disk?

Yes it appears largest when its a thin crescent

What happens when you burn wood?

Chemical potential energy transforms into thermal energy

Biggest high tide

New Moon overhead

When a gas cloud collapses under its own gravity it heats up because...

Gravitational potential energy turns to thermal energy

The energy of a photon is higher if...

The frequency is higher

What do we see in the sun?

Hot dense gas or solid surrounded by a diffuse gas.