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What is currently the best way to estimate the age of the universe?

Hubble's Constant

What is the current best estimate of the age of the universe?

14 billion years old

If the universe is homogeneous and isotropic, Hubbles Law implies

Universal Expansion

What kind of universe would collapse on itself

Closed Universe

What kind of universe represents the critical point were the universe never collapses on itself

Flat Universe

what kind of properties do irregular galaxies have?

typically smaller than spiral galaxies, exhibit vigorous star-forming activity, some show evidence for prior collision or close encounter with another galaxy.

What is true about galaxies that are measured from earth with high speeds?

They are moving away from Earth and are farther from Earth than galaxies with lower speeds.

what can we say about the galaxies measured from earth at low speeds?

They are moving away from earth and are closer to earth than galaxies with high speeds.

Suppose that galaxy B is twicw as far from Earth as galaxy A. Hubbles law predicts that galaxy B will be moving away from earth with approximatley _____.

twice the velocity of galaxy A.

True or False: Most Galaxies are spirals like the Milky Way

False

True or False: Most elliptical galaxies contain only young stars.

False

True or False: Type I supernovae can be used to determine distances to galaxies.

True

True or False: Active galaxies can emit thousands of times more energy than our own galaxy

True

Using the method of standard candles, we can, in principal, find the distance to a campfire if we know.

The number of logs used

About how many galaxies are within 30 mega parsecs of the sun

a few thousand

Hubble's Law states that

The greater the distance to a galaxy, the greater the galaxy's redshift.

If the light from a galaxy fluctuates in brightness very rapidly, the region producing the radiation must be

very small

Quasar spectra are

strongly redshifted

The flattest of ellipticals are class

E7

what is common to spiral galaxies?

ongoing star formation and emission nebula in the arms

The astronomer who orginally classified galaxies into Spiral, Elliptical, and Irregular

Edwin Hubble

Compared to our own galaxy, elliptical galaxies

show no evidence of ongoing star formation

Large and small Magellanic Clouds fall into Hubble's Class

Irr I

The greatest variation in size mass and luminosity occurs in

elliptical galaxies

A galaxy with little cool gas or dust and no evidence of ongoing star formation is most likely a

elliptical

Within the boundaries of the constellations Coma and Virgo are found in

the largest nearby superclusters of galaxies

What are Type I supernovae used for?

Standard candles for determining distances to other galaxies

Tully-Fisher relation exists between the galaxy's luminosity and its

rotation

According to Hubble's Law, a galaxy with a velocity of 25,000km/s will be

400 million parsecs away

According to Hubble's Law, the greater a galaxy's red shift, the

farther it is from us

The nearest lobe radio galaxy to our Milky Way is

Centaurus A

In active galaxies, their central engines may be temporarily fed by

a close encounter with a neighbor galaxy

The key to finding quasar's distances was

the huge red shifts of the hydrogen lines in 3C273

In what sense are the quasars "quasi-stellar"?

In short time exposures, their images looked stellar

True or False: Collisions between galaxies are rare and have little or no effect on the stars and interstellar gas in the galaxies involved

False

True or False: On the largest scales, galaxies in the universe appear to be arranged on huge sheets surrounding nearly empty voids.

True

A galaxy containing substantial amounts of dark matter will

Spin faster

The fraction of mass of the universe made up of dark matter is

more than 90%

Many nearby galaxies may have been

much more active in the past

As we look at larger and larger scales the universe we find

a larger and larger percentage of the matter is dark

Based on galactic rotation curves and cluster dynamics, we think of dark matter

comprieses of over 90% of the entire mass of the universe

A radio galaxy whose lobes are swept back as if forming a tail, what dose this probably indicate

This is evidence for intergalactic matter.

Collisions between galaxies is thought to

be commonplace

collisions between galaxies

cause the gas and dust clouds to collide, leading to rapid star formation

Where are large dust clouds predominately located in the galaxy M51?

Within or on the edges of the spiral arms

Where are the ionization nebulae predominately located in the galaxy M51?

Within or on the edges of the spiral arms of the galaxy

Why are the ionization nebulae so bright?

They are regions where gas is ionized by hot, young stars

True or False: Cepheid Variable can be used to determine the distances the nearest galaxies

True

True or False: The Galactic halo contains about as much gas and dust as the Galactic disk

False

True or False: Stars and Gas in the Galactic disk move in roughly circular orbits around the Galactic Center.

True

True or False: The most likely explanation of the high-speed motion of stars and gas near the Galactic center is that stars and gas are orbiting a supermassive black hole

True

In the Milky Way Galaxy, our sun is located

about halfway out from the center

The first stars that formed in the Milky Way now have

random orbits in the halo

Most of the mass of the milky way exists in the form of

dark matter

A cepheid variable star with a luminosity 1000 times that of the sun has a pulsation period of roughly

3 Days

In structure, our milky way is most similar to

The Andromeda Galaxy

The first attempt to map the Galaxy via star counts was done by

William Herschel in the late 18th century

The RR Lyrae stars all have periods of

a few hours

For finding the distances to globular clusters, Harlow Shapley used

RR Lyrae variables

Why was Herschel's for mapping the galaxy flawed?

He relied on on visual wavelengths, which are obscuredd by dust

What kind of variable stars would be classified as a RR Lyrae?

F giant with a period of 14 hours

The period luminosity relation is crucial in finding distances with

Cepheid Variables

Harlow Shapley found the Milky Way was

much larger than previously thought

Galactic Disks appear blue because of

O and B blue giants are much brighter than G, K, or M dwarfs

From the Sun, the distance to the Galactic Center is about

8 killa-parsecs

Detailed measurements of the disk and central bulge region of our galaxy suggest our Milky Way is a

Barred spiral galaxy

Between us and the Galactic Center, the Milky Way has a mass of

100 billion suns

In our location in the Milky Way, the galactic disk is only about ________ ly thick

1,000

What two observations allow us to calculate the galaxy's mass?

The suns orbital velocity and its distance from the Galactic Center

The dark halo is now believed to extend at least

50 Kila-parsecs

Most of the mass of the Milky way seems to exist in the form of

dark matter out in the halo

True or False: Herschel believed the Milky Way was a disk of stars, while Shapely found the extended halo more like a ball

True

True or False: Shapley found the globulars were strongly concentrated toward Sagittarius

True

True or False: Population I stars came billions of years before Population II stars

False

True or False: Stars within an emission nebula, such as M42, are considered Population I stars

True

True or False: The Globular star clusters are the most obvious examples of population II around us

True

The bright blue stars of Orion's Belt are Population I, while our Yellow Sun is population II

False

True or False: It would be very unlikely to find a massive, young star out in the halo

True

True or False: Like our solar system, the whole Milky Way is about five billion years old

False

True or False:The density wave theory attempts to explain why the spiral arm structure persist over a long time

True

True or False: Dark Matter has not been observed at any electromagnetic wavelength

True

During the history of the universe, what important event occurred about 0.001 seconds after the Big Bang?

Most matter in the early universe was annihilated by antimatter

What important event occurred earliest in the history of the universe

Space time rapidly expanded during a brief period of inflation

During the history of the universe, what important event occurred about 380,000 years after the Big Bang

Light began to travel freely through the universe.

Essentially all the hydrogen nuclei that will ever exist in our universe was created

by the time the universe was about 3 minutes old

Compared to when the cosmic microwave background was first released, the radiation of the cosmic microwave background today is

fainter and has most of its photons at longer wavelengths

when the universe was 10 years old, the density of radiation was

much greater than that of matter

The concept that on the grandest of scales, the universe is similar in appearance everywhere is

homogeneity

Because almost all galaxies show redshifted spectra, we know that

the universe is expanding.

If Euclid is right, then Omega is

1.0

The darkness of the night sky in an infinite universe is addressed in

Olbers's paradox

From the 1970s to the present, the accepted value of H has almost doubled, so

the age of the universe is half what we believed

In what model will the universe stop expanding

Closed Universe

If Omega is less than 1 then

the universe will expand forever

What is the meaning of a "closed" universe?

The universe will someday stop expanding and begin collapsing inward

The latest studies from ________ led to the discovery of "dark energy."

Type I supernovae at very large red shifts

What temperature has the Big Bang cooled to by now?

Just over 2.7K

The discovery of the cosmic microwave background was important because

it was was experimental verification of a prediction from the Big Bang theory

The Big Bang formed

hydrogen and helium, but nothing else

Why didn't elements heavier than helium form in the first minutes of creation?

When He-4 was formed, the expansion cooled the cosmos below 100 million K

The satellite that found the ripples in the cosmic background that led to galaxies is

COBE

True or False: In the cosmological principle, we can easily test cosmic homogeneity with the red shift surveys, but isotropy cannot be so tested.

False

True or False: It appears that nearly three times as much dark energy exists in the universe than normal and dark matter combined

True

True or False:Deuterium abundance suggests that normal matter makes up only 3-4% of the critical density.

True

True or False: The background hiss that Bell Labs detected was the best observational evidence for the Big Bang.

True

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