Question 1

We can estimate the mass of the central black hole in the Milky Way by measuring the orbital speeds of stars near it.

Accepted Answer

A) True 
 B)False

Question 2

The energy of a cosmic ray is given by $\gamma$mc2, where m is the mass of the particle, c is the speed of light, and$\gamma$ is the Lorentz factor and   . If a cosmic ray proton is traveling at a speed of $\nu$= 0.999999c, what is its energy? How does that compare to the kinetic energy of a grape thrown up in the air and caught in your mouth? Assume the grape has a mass of about 5 grams and a speed of 0.5 m/s when you catch it. The mass of a proton is 1.7 * 10-27 kg.

Accepted Answer

The cosmic ray proton has a Lorentz fact

Question 3

The Sun is rotating about the center of the galaxy at roughly 220 km/s at a distance of about 8 kpc. How long will it take to complete one revolution? How many times has the Sun orbited the galaxy in its lifetime?

Accepted Answer

Disk stars rotate in approximately circu

Question 4

The stars in the disk of the Milky Way near the Sun have:

Accepted Answer

A)  chemical abundances similar to the Sun 
B)  much higher velocities than the Sun 
C)  chemical abundances that are on average 10 times higher than the Sun 
D)  much lower velocities than the Sun 
E)  chemical abundances that are on average 10 times lower than the Sun 
A)  chemical abundances similar to the Sun 
B)  much higher velocities than the Sun 
C)  chemical abundances that are on average 10 times higher than the Sun 
D)  much lower velocities than the Sun 
E)  chemical abundances that are on average 10 times lower than the Sun

Question 5

How do we think the central black hole in the galaxy primarily grew to its current mass?

Accepted Answer

A)  ordinary stellar evolution of massive stars 
B)  merger of close binary stars 
C)  shock waves from supernova explosions 
D)  dark matter clumping together 
E)  accretion of nearby gas 
A)  ordinary stellar evolution of massive stars 
B)  merger of close binary stars 
C)  shock waves from supernova explosions 
D)  dark matter clumping together 
E)  accretion of nearby gas

Question 6

There is a 109 M $\odot$ black hole at the center of the Milky Way that is rapidly accreting stars and gas.

Accepted Answer

A) True 
 B)False

Question 7

Describe the differences between the ages and chemical abundances of globular and open star clusters.

Accepted Answer

Globular clusters are very old, 12-13 bi

Question 8

The presence of dwarf galaxies around the Milky Way supports what picture of our galaxy's formation?

Accepted Answer

A)  The galaxy formed by the merger of two large galaxies, which scattered their dwarf companions to large distances. 
B)  The galaxy originally formed with no dark matter but gained its dark matter by the absorption of smaller dwarf systems. 
C)  The galaxy formed in a giant explosion caused by the violent collisions of clouds of dark matter. 
D)  The galaxy formed a long time ago and has been passively evolving since. 
E)  The galaxy formed by the merger of smaller systems. 
A)  The galaxy formed by the merger of two large galaxies, which scattered their dwarf companions to large distances. 
B)  The galaxy originally formed with no dark matter but gained its dark matter by the absorption of smaller dwarf systems. 
C)  The galaxy formed in a giant explosion caused by the violent collisions of clouds of dark matter. 
D)  The galaxy formed a long time ago and has been passively evolving since. 
E)  The galaxy formed by the merger of smaller systems.

Question 9

Globular clusters are found in which stellar subgroups of the galaxy?

Accepted Answer

A)  the disk 
B)  the halo 
C)  the bulge 
D)  both the halo and the inner disk 
E)  the outer halo 
A)  the disk 
B)  the halo 
C)  the bulge 
D)  both the halo and the inner disk 
E)  the outer halo

Question 10

Open star clusters primarily inhabit which part of spiral galaxies?

Accepted Answer

A)  disk 
B)  halo 
C)  bulge 
D)  nucleus 
E)  satellite galaxies 
A)  disk 
B)  halo 
C)  bulge 
D)  nucleus 
E)  satellite galaxies

Question 11

A dwarf galaxy is currently being ripped apart and accreted onto the Milky Way.

Accepted Answer

A) True 
 B)False

Question 12

Studying standard candles in globular clusters offered the first conclusive proof that our galaxy was much __________ than originally believed.

Accepted Answer

A)  smaller 
B)  rounder 
C)  older 
D)  flatter 
E)  larger 
A)  smaller 
B)  rounder 
C)  older 
D)  flatter 
E)  larger

Question 13

Our galaxy is classified as an Sd galaxy in the Hubble sequence.

Accepted Answer

A) True 
 B)False

Question 14

Calculate the size of the event horizon of the supermassive black hole at the center of the Milky Way, the mass of which is 4 * 106 M $\odot$ . Give your answer in units of AU.

Accepted Answer

R_s= 2GM/c² = 2* 6.

Question 15

Open clusters are only found in the disk of the Milky Way; globular clusters are only found in the halo of the Milky Way.

Accepted Answer

A) True 
 B)False

Question 16

Halo stars near the Sun are distinguished from disk stars by what characteristics?

Accepted Answer

A)  low chemical abundances and low relative velocities 
B)  high chemical abundances and high relative velocities 
C)  low chemical abundances and high relative velocities 
D)  high chemical abundances and low relative velocities 
E)  equal chemical abundances and high relative velocities 
A)  low chemical abundances and low relative velocities 
B)  high chemical abundances and high relative velocities 
C)  low chemical abundances and high relative velocities 
D)  high chemical abundances and low relative velocities 
E)  equal chemical abundances and high relative velocities

Question 17

If you wanted to study the properties of nearby stars that were some of the first stars to form in the Milky Way, but were NOT members of a globular cluster, how could you go about finding them?

Accepted Answer

You would look for stars that were membe

Question 18

The youngest disk stars are found in a very thin plane in the disk.

Accepted Answer

A) True 
 B)False

Question 19

The chemical composition of a star's atmosphere tells us:

Accepted Answer

A)  how much nuclear burning has gone on in the star 
B)  the star's evolutionary stage 
C)  how many planets have fallen onto the star in its lifetime 
D)  the chemical composition of the cloud from which the star formed 
E)  the amount of heavy elements the entire galaxy had when the star was formed 
A)  how much nuclear burning has gone on in the star 
B)  the star's evolutionary stage 
C)  how many planets have fallen onto the star in its lifetime 
D)  the chemical composition of the cloud from which the star formed 
E)  the amount of heavy elements the entire galaxy had when the star was formed

Question 20

Our galaxy is a typical barred spiral galaxy.

Accepted Answer

A) True 
 B)False

Exam 21: The Milky Waya Normal Spiral Galaxy

We can estimate the mass of the central black hole in the Milky Way by measuring the orbital speeds of stars near it.

The Sun is rotating about the center of the galaxy at roughly 220 km/s at a distance of about 8 kpc. How long will it take to complete one revolution? How many times has the Sun orbited the galaxy in its lifetime?

The stars in the disk of the Milky Way near the Sun have:

How do we think the central black hole in the galaxy primarily grew to its current mass?

There is a 109 M ⊙\odot⊙ black hole at the center of the Milky Way that is rapidly accreting stars and gas.

Describe the differences between the ages and chemical abundances of globular and open star clusters.

The presence of dwarf galaxies around the Milky Way supports what picture of our galaxy's formation?

Globular clusters are found in which stellar subgroups of the galaxy?

Open star clusters primarily inhabit which part of spiral galaxies?

A dwarf galaxy is currently being ripped apart and accreted onto the Milky Way.

Studying standard candles in globular clusters offered the first conclusive proof that our galaxy was much __________ than originally believed.

Our galaxy is classified as an Sd galaxy in the Hubble sequence.

Calculate the size of the event horizon of the supermassive black hole at the center of the Milky Way, the mass of which is 4 * 106 M ⊙\odot⊙ . Give your answer in units of AU.

Open clusters are only found in the disk of the Milky Way; globular clusters are only found in the halo of the Milky Way.

Halo stars near the Sun are distinguished from disk stars by what characteristics?

If you wanted to study the properties of nearby stars that were some of the first stars to form in the Milky Way, but were NOT members of a globular cluster, how could you go about finding them?

The youngest disk stars are found in a very thin plane in the disk.

The chemical composition of a star's atmosphere tells us:

Our galaxy is a typical barred spiral galaxy.

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

There is a 10⁹ M _$\odot$ black hole at the center of the Milky Way that is rapidly accreting stars and gas.

Calculate the size of the event horizon of the supermassive black hole at the center of the Milky Way, the mass of which is 4 * 10⁶ M _$\odot$ . Give your answer in units of AU.