How fast would a galaxy 2,000 megaparsecs away be moving with respect to us, according to Hubble’s Law? Hint: H0 = 70 km/s/Mpc 1,400 km/s 14,000 km/s 140,000 km/s 140 km/s

How fast would a galaxy 2,000 megaparsecs away be moving with respect to us, according to Hubble’s Law? Hint: H0 = 70 km/s/Mpc 1,400 km/s 14,000 km/s 140,000 km/s 140 km/s

The number of stars in the galaxy is approximately ____________. 2-5 billions 50-100 millions 100-400 billions 50-80 billion

The number of stars in the galaxy is approximately ____________. 2-5 billions 50-100 millions 100-400 billions 50-80 billion

The number of stars in the galaxy is approximately ____________. 2-5 billions 50-100 millions 100-400 billions 50-80 billion

If a galaxy is at a distance of one billion light years, then which is true? We see the galaxy the way it was one billion years ago We see the galaxy the way it was when the Universe was one billion years old We have no knowledge of anything at that distance We see the galaxy the way it will be in one billion years

We see the galaxy the way it was one billion years ago If a galaxy is at a distance of one billion light years, then which is true? We see the galaxy the way it was one billion years ago We see the galaxy the way it was when the Universe was one billion years old We have no knowledge of anything at that distance We see the galaxy the way it will be in one billion years

Which of the following galaxy types contains stars but almost no gas? Barred spiral Spiral Elliptical Irregular

Which of the following galaxy types contains stars but almost no gas? Barred spiral Spiral Elliptical Irregular

All known galaxies are moving away from us and thus are redshifted TRUE FALSE

All known galaxies are moving away from us and thus are redshifted TRUE FALSE

White dwarf supernovae What distance measurement technique works best for the closest galaxies that we can observe? Radar Cepheid Parallax White dwarf supernovae

White dwarf supernovae What distance measurement technique works best for the closest galaxies that we can observe? Radar Cepheid Parallax White dwarf supernovae

The mass of the galaxy is approximately ______ solar masses. 100 15,000,000 600,000 850,000,000,000

The mass of the galaxy is approximately ______ solar masses. 100 15,000,000 600,000 850,000,000,000

Gas, dust, and spiral arms are found in the galactic ______. Bulge Disk Halo

Gas, dust, and spiral arms are found in the galactic ______. Bulge Disk Halo

Spiral arms do not contain Open clusters Supermassive black holes High stellar densities Star forming regions

Supermassive black holes Spiral arms do not contain Open clusters Supermassive black holes High stellar densities Star forming regions

Which of the following is the Milky Way Galaxy Barred spiral Spiral Irregular Elliptical

Which of the following is the Milky Way Galaxy Barred spiral Spiral Irregular Elliptical

Tully-Fisher relation Which of the following is a standard candle used to measure the distance to distant galaxies? Doppler effect Parallax Radar Tully-Fisher relation

Tully-Fisher relation Which of the following is a standard candle used to measure the distance to distant galaxies? Doppler effect Parallax Radar Tully-Fisher relation

The oldest stars are likely to be found in the: Halo Bulge Disk

The oldest stars are likely to be found in the: Halo Bulge Disk

What is the cosmological principal? The Universe looks about the same everywhere Dark matter fights dark energy The Universe was created during the Big Bang event The Universe is expanding

The Universe looks about the same everywhere What is the cosmological principal? The Universe looks about the same everywhere Dark matter fights dark energy The Universe was created during the Big Bang event The Universe is expanding

Edwin Hubble used observations of _______ to determine the distance to the Andromeda Galaxy Cepheids Comets Neutron stars White dwarfs

Edwin Hubble used observations of _______ to determine the distance to the Andromeda Galaxy Cepheids Comets Neutron stars White dwarfs

Which galaxy is closest to us? The Small Magellanic Cloud The Large Magellanic Cloud The Andromeda Galaxy The Sagittarius Dwarf Spheroidal Galaxy

The Sagittarius Dwarf Spheroidal Galaxy Which galaxy is closest to us? The Small Magellanic Cloud The Large Magellanic Cloud The Andromeda Galaxy The Sagittarius Dwarf Spheroidal Galaxy

The Milky Way Active Galactic Nuclei Types of Galaxies Galaxy Evolution The Cosmic Distance Ladder Supermassive Black Holes $100 $200 $400 $600 $800 $1000 $2000

What type of galaxy is the Milky Way?

A barred spiral type

What is the closest galaxy to the Milky Way?

Sagittarius Dwarf Spheroidal Galaxy

Roughly how many stars are located in the Milky Way?

100-400 billion

In 1 trillion years, the Milky Way will have little gas, if any In 1 trillion years, the Milky Way will have little gas, if any. Where will the matter that comprised the current gas be located?

Mostly locked into white dwarfs and low-mass stars

Roughly how long does it take for the Sun to complete one orbit around the Milky Way

230 million years

What types of stars are found in each of the three major components of a galaxy like the Milky Way?

Disk: Mostly young stars Central Bulge: Mix of old and young stars Halo: old stars

How can we distinguish halo stars passing through the disk of the galaxy from disk stars?

By studying the motion and composition of the stars By studying the motion and composition of the stars. Halo stars are metal poor, old stars and travel in rather random orbital orientations. Disk stars are younger, more metal rich and orbit in the same orientation, excepting some up and down motion

A Quasar is an example of a(n)

Active galactic nuclei

The luminosity of an AGN (active galactic nuclei) can exceed _______.

One trillion times the luminosity of the Sun (1012 LSun)

AGN vary rapidly. This means that they are located within a region of a host galaxy which is ________

Very small (in fact within a space smaller than the Solar System!)

Quasars have a very large redshift this means that ___________.

1) They are generally very distant 2) They were more common early in time 3) Galaxy collisions might turn them on 4)Nearby galaxies might hold dead quasars

The source of AGN light is ____________

Accretion of gas onto a supermassive black hole

The source of the radio wave signals in radio galaxies is/are __________.

Vast jets of plasma, with electrons moving close to the speed of light

Why don’t all AGN appear the same?

Viewing orientation Quasar or Seyfert Galaxy Blazar Radio Galaxy

E0 galaxies are more _______ than E7 galaxies

Spherical

Starburst galaxies are so called because _________.

They are experiencing a period of rapid star formation

Name one difference between a Sa and a Sc type galaxy

In Sa galaxies, the arms are tighter and the bulge is more prominent

Between elliptical and spiral galaxies, which is more likely to have young stars, and gas?

Spiral galaxies

What is a lenticular galaxy?

A galaxy with a disk and prominent bulge but with no obvious spiral arms. Although they can have dust, they have little gas and do not have much star formation and are mostly older stars

Between elliptical and spiral galaxies, which is more likely to have young stars, and gas?

Spiral galaxies

Where in a spiral galaxy would you most likely find globular clusters?

The halo

Are galaxy collisions more common now than in the past?

No! They were more common in the past, when the Universe was denser and galaxies were generally closer together

What type of galaxy will result from the collision of Andromeda and the Milky Way?

An elliptical galaxy

Why do galaxy mergers result in increased star formation?

Because gas clouds collide which increases the density of these clouds and then triggers star formation

Why does dark matter remain in a halo around galaxies during galaxy formation?

Because it cannot radiate away energy

In what way does density of a protogalactic cloud determine whether a galaxy formed into a spiral or an elliptical galaxy?

Elliptical galaxies come from denser clouds that cool and form stars before the gas is able to settle into a disk

What does it mean that fragmentation in galaxy formation is a bottom-up mechanism?

It means that smaller structures collapse first and then merge to make a bigger structures.

How did supernovae explosions of the first stars contribute to the formation of disks in galaxies?

The explosions prevented gas from forming more stars The explosions prevented gas from forming more stars. This gas was able to settle into a spinning disk via conservation of angular momentum

How are Cepheids used to measure the distances to nearby galaxies?

Using Leavitt’s Law which shows that the period of a Cepheid is related to its luminosity

How is the Tully-Fisher relationship used to measure distances to galaxies?

Astronomers measure the rotation speed of stars in the galaxy using spectroscopy (the Doppler effect). This is related to the luminosity of the galaxy,

What is the cosmological principal?

The Universe looks the same everywhere. This means that expansion looks the same to all observers and the universe has no center or edges

How is Hubble’s Law used to get distances to distant galaxies?

Astronomer’s measure the recessional velocity (moving away from us) of the galaxy. This is related to distance by: V=H0* D.

Do all galaxies show recessional redshift?

No! Distant galaxies do because of the expansion of the Universe but some nearby galaxies are moving toward the Milky Way and these show blue shifts.

What is lookback time?

The time it took the light of an object to reach us The time it took the light of an object to reach us. Because light travels at a finite speed, this means we are looking at these objects in their past.

Why can’t we use parallax to measure distances to galaxies?

Because parallax is inverse to distance, this means that objects at very big distances show small parallaxes. We can’t detect the change!

How do astronomers know that the Milky Way has a supermassive black hole in its center?

The orbits of stars close to the center of the Milky Way suggest a very massive an object in a very small area.

What is the upper mass limit for a supermassive black hole?

Roughly 50 billion solar masses

What does the presence of quasars in the early Universe suggest about supermassive black holes?

That even in the first massive galaxies, supermassive black holes were present. Thus they formed early in the history of the Universe

What does the fact that the mass of a galaxy’s central black hole is related to the mass of the bulge of a galaxy suggest?

That the development and growth of the supermassive black hole is related to galaxy evolution

What is the M-sigma relation?

The relation between the stellar velocity dispersion (sigma) in the bulge of a galaxy and the mass of its supermassive black hole. Galaxies with higher sigma, have a more massive central black hole

If you want to look toward the center of the Milky Way and its supermassive black hole, which constellation should you look at?

Sagittarius

If AGN are evidence that galaxies have supermassive black holes and the Milky Way has a supermassive black hole, then why isn’t it an AGN?

Because the Milky Way’s supermassive black hole is not currently “consuming” enough material and probably lacks a large enough accretion disk