Download ASTR 101 Final Study Guide Use as a guide to the topics as you

ASTR 101 Final Study Guide
Use as a guide to the topics as you prepare for the final.
Not all chapter were submitted and there were duplicates. If your chapter study guide is not
here, email to me and I’ll post an addition to the study guide.
Good luck and thanks to all who contributed!
Chapter 6
For this chapter, I think we should focus on the Earth’s
Size
Shape
Composition
Density
Identify cross section and interior
Differentiation
Convection process
Causes of magnetic field
Precession
What shape is the earth and what is the reason for it?
What is the earth density?
What is the earth composition?
How did the Greeks know the earth is round?
Draw and level the three interior regions of the earth?
How do we know its structure?
What is the name of the process where the earth’s structure interior structure is layered so that
the sense heavier material is in the center and the lighter material is on the surface?
What are the types of seismic waves in the earth? What are the benefits that astronomers can get
from them?
Why is so hot in the inside of the earth? Explain what happens with the radioactive elements and
the effect that they cause.
What can we determine with the daughter atoms and how?
What is the name of the circulating movement of a heated liquid or gas? Who is it related to the
earth?
The earth’s surface activity (volcanoes, earthquakes, and the movement of the continents is
accounted by the theory of the _____________ ___________.
What are the three elements needed in order to have a magnetic field?
What are the main gases that compound the earth’s atmosphere?
Why is the Ozone Layer important on the earth?
Briefly explain what the Coriolis Effect is.
What is the name of the process that makes the earth’s rotation axis swing slowly in a circle,
similar to the” wobble” of a spinning top?
Ch. 7 Final Study guide
Surface Features
 Highlands: Bright rugged areas composed mainly of anorthosite and pitted with craters
 Maria: smooth, dark areas surrounded by highlands and composed primarily of basalt
-Which is older?
 Craters: circular features with a raised rim and range in size from less than a centimeter to
a few hundred kilometers some of the larger craters have mountain peaks at their center
 Rays: Long, light streaks of pulverized rock radiating away from many craters
 Rilles: Lunar canyons carved either by ancient lava flows or crustal cracking
- What is the origin of nearly all lunar surface features?
Interior of Moon
 Crust: is composed of silicate rocks rich in aluminum and poor in iron
 Mantle: Relatively thick, extending 1000 km down; Appears Cold and Ridged
 Core: The Moon’s low average density (3.3 g/cm3) tells us interior has little iron
-The relatively cold Moon interior, low iron/nickel content, and slow rotation imply
no magnetic field
Rotation
 The fact that the Moon rotates at the same rate as it orbits [synchronous rotation]
 The Moon’s orbit is tilted about 5° [with respect to the ecliptic plane] [It is also tilted
with respect to the Earth’s equator]
Large Impact Hypothesis
 Moon formed from debris blasted out of the Earth by the impact of a Mars-sized body
 Age of lunar rocks and lack of impact site on Earth suggests collision occurred at least
4.5 billion years ago
- What does this idea explain about the Moon and Earth?
Tides
 The Moon exerts a gravitational force on the Earth that is stronger on the side closest to
the Moon and weakest on the far side
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- Differential force gravity
Earth’s rotation leads to two high/low tides per day
- Spring vs. Neap Tides
Tides create forces that slow the Earth’s rotation and move the Moon farther away [tidal
braking]
- What does Tidal Braking cause?
Full Moon names for extra credit?
Chapter 9 Study Guide
What is the atmosphere of Venus mostly contained of?
96% carbon dioxide 4% nitrogen and other small gasses
Why is Venus’s temperature so hot?
Venus’s carbon dioxide atmosphere creates an extremely strong ______ ________ _______.
What are the clouds of Venus made of?
Sulfuric acid
Why does Mercury have so many craters and the Earth so few?
Erosion and plate tectonic activity have destroyed most of the craters on the earth.
Which body in the inner Solar System has the densest atmosphere?
Venus
Which of the following features are shaped by all of the terrestrial planets?
A silicate mantle
An iron core
What evidence suggests that liquid water was once present on the Martian surface? (Select all
that are true)
Branching channels in the shape of riverbeds
Teardrop-shaped islands behind craters
Compounds that form in water have been identified in the rocks
Chapter 9 Study Guide
Possible Questions:
What is the surface of Mercury like?
Mercury’s surface is one of the hottest during the day and one of the coldest during the night.
This is due to the slow rotation as well as the absence of an atmosphere.
Does Mercury have an atmosphere? Why or why not?
Mercury has little to no atmosphere due to the fact that it is so close to the Earth that there are no
gases that can remain. Mercury also has a small mass which accounts for the little amount of
gravity causing the lack of an atmosphere.
What is peculiar about Mercury's rotation? What causes this oddity?
Mercury’s rotation period is extremely slow: for every 3 spins, it orbits the sun twice. This is due
to the Sun’s tidal forces - resonance effect.
Why is Venus so hot?
The reason for why Venus is so hot is because it’s atmosphere contains 300,000 more carbon
dioxide than the Earth which creates an extremely strong runaway greenhouse effect.
How hot is Venus?
864F
Astronomers can measure the time since the last eruption of a volcano on Mars by:
Counting the number of craters on its slopes.
What makes the Inner Planets different:
Small size (Earth is the largest, Mercury is the smallest)
Have solid surfaces and thin/no atmosphere
Greater Density
Varied atmospheres (Mercury has none, Venus is almost completely carbon dioxide, Earth’s is
nitrogen with some Oxygen, Mars is similar to Venus but much thinner)
Spin Slowly (Earth spins the quickest - 23 hrs and 56 mins, Venus is the slowest - 243 days)
Orbit the Sun quickly - due to their distance
Few to no Moons (Earth has one and Mars has 2)
No Rings
Mercury:
Smallest Terrestrial Planet
⅓ radius and 1/28th mass of the Earth
Surface covered with craters, rays and scarps
Largest crater: Caloris Basin
Temperature is extremely hot during the day - 820 F and cold at night - -320 F
Due to the poles receiving almost no sunlight, they contain some ice
No atmosphere due to small mass (small gravitational attraction) and being too close to the sun
High density (5.4 g/cm^3) which indicates an iron-rich interior with only a thin rock (silicate)
mantle
Spins slowly (58.6 Earth days), which is 2/3rds of its orbital period - 87.9 Earth days
Extremely long solar days - 176 Earth days. This is due to Resonance which is created with
Kepler’s second law of planetary motion (the orbit is very elliptical).
Venus:
Thick atmosphere: 96% carbon dioxide
Closest in diameter and mass to Earth
Clouds are made of sulfuric acid
Pressure 100x that of the Earth’s
The Carbon Dioxide atmosphere creates a strong runaway greenhouse effect
Two major highland regions: Ishtar Terra and Aphrodite Terra
One rotation is 243 days (longest in the SS)
Spins in retrograde (backward)
One day is 117 Earth days
The slow and retrograde spin may suggest a collision shortly after its birth
Mars:
Diameter is half and mass is 1/10th of the Earth
One day is only 39 minutes longer than an Earth day
Very cold due to a very weak greenhouse effect
Largest Volcano in the solar system: Olympus Mons
Polar caps shrink up in size during certain times due to extreme seasonal changes
The Red surface color comes from the iron minerals in its surface rocks
There is evidence of water being present at some point
Weak atmosphere: 95% carbon dioxide, 3% nitrogen
Has two small moons: Phobos and Deimos (captured asteroids)
Chapter 10 Study Guide questions
1. How do Jupiter’s mass and radius compare with the Earth’s? How do they compare with those
of the other outer planets?
2. What does Jupiter look like?
3. How do astronomers know what lies inside the outer planets?
4. What are the major gaseous substances that make up Jupiter and Saturn?
5. What is the interior structure of Jupiter and Saturn thought to be?
6. Do Jupiter and Saturn have solid surfaces?
7. What are Jupiter’s internal heat sources?
8. What sorts of atmospheric motion and activity are observed in Jupiter? What is the Great Red
Spot?
9. What sort of activity has been seen on Io? What is Io’s heat source thought to be?
10. What are the rings of Saturn made of? How do astronomers know this?
11. What creates the gaps between the rings?
12. How might the rings have formed?
13. What is the Roche limit? Why does such a limit exist?
14. What is unusual about Uranus’s rotation axis? What might explain this peculiarity?
15. How do Uranus and Neptune differ from Jupiter in their interiors?
16. Why are Uranus and Neptune so blue?
17. Why are the outer planets so large?
18. What are the satellites of the outer planets thought to be composed of?
Which have atmospheres? What might be special about Europa?
Chapter 12 Review
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Know how to find the radius of a star if we know the Luminosity (L) and Temperature
(T)
o R= sq root(L/T4)
o No other math!
Know size comparison of the Sun to the Earth
o 108 Earth’s across
o Or 1/3rd of one million in mass (333,000)
Know approximate temperatures of the Sun
o 5800 Kelvin at its surface
o 15 Million Kelvin at its center
Know how we got those numbers
o Star models
o Weins law – based on the color of the star we can infer it’s temperature (Yellow
5800k)
o Neutrinos can tell us how hot the center is
Describe how we determine the layers and structure of the Sun
o Solar/helioseismology
Know the density and composition of the Sun
o Hydrogen and Helium
o 1.4 density
Know how powerful the Sun is
o 400 Trillion trillion watts
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We can calculate this by calculating the energy from earth in a square
meter, then calculate how many square meters cover the surface of the
sun.
Know how the Sun produces it’s energy
o The fusion of Hydrogen  helium, aka matter to energy
o 4 million tons of mass is lost a second
Know the layers of the sun from the core to the surface and their aprox temperatures
(which is hottest and which is coolest)
o Thermonuclear core
o Radiative zone
o Convective zone
o Photosphere – Coolest (hotter farther out and closer in)
o Chromosphere
o Corona
Know what makes the sun a sphere and holds it together
o Gravity pulls the sun in, pressure pushes it out
 This is called Hydrostatic equilibrium (the forces are in balance)
Know what a prominence is
o The “tongues of flame” coming from the corona
Know what a Flare is
o A cloud of energy that plumes from the surface of the sun, which can actually
affect us on earth
Know what a CME is
o Corona mass ejection
 Can actually cause the aurora borealis
Know what a magnetogram is and what it’s use is
o ZEEMAN
o ( (|) )
o Splits the black line into several parts to indicate magnetic field
Know what Sun spots are
o Places where the sun is cooler
Know the Sun spot cycle and their possible relation to Earth
o 11 year (on average) cycle, but switches polarity, so takes another 11 years to
revert
o The Maunder Minimum when a time in 1645 through 1715 that sun spots were
very rare and caused substantially lower temperatures on Earth
Study Guide for Astronomy: Chapter 13
1. A star that is cool and very luminous must have a very large radius.
2. Which of the following stars is hottest? An M star
3. A binary system has a period of about 100 years and an average separation of 30 AU. Its
combined mass is about 3 solar masses.
4. In a sample of nearby stars, about what percentage will lie on the main sequence? 90%
5. In what part of the H-R diagram do white dwarfs lie? Upper right
6. This statement is true about stellar luminosities…luminosities have a smaller ranger than
masses.
7. If two stars have the same luminosity, but one appears only one-quarter as bright as the
other, you can conclude that the dimmer star is 2 times farther away.
1. A star is at a distance of 10.0 parsecs from the Sun. What is the distance in light-years?
32.6 light-years
2. A light source emits 100 watts of visible radiation and is located at a distance of 1 meter
from an observer. Now suppose the distance is moved to 2 meters from the observer.
Which of the following statements correctly describes the change in observed properties
of the source? The luminosity stays the same and the brightness is reduced to ¼
3. The star Procyon has an apparent magnitude of 0.4, while Rigel’s is 0.1. Which of the
two stars appear brighter to an observer on Earth? Rigel
4. Knowing the luminosity and apparent brightness of a main sequence stars allows
calculation of the distance of the star.
5. Two stars have the same radius. The temperature of star A is twice that of star B,
compared to B, the luminosity of star A is 16 times larger.
6. What kind of information can astronomers obtain from the spectrum of a star? The
Composition and temperature of the stars atmosphere, rotation speed and luminosity.
7. Which of the stars is the hottest? B is the hottest
8. Two stars in a binary system have an orbital period, P, of 5 years and an orbital
separation, a, of 10 AU. What is their combined mass? 40 solar masses
9. In a sample of nearby stars, about what percentage will lie on the main sequence? 90%
10. In what part of the H-R diagram do white dwarfs lie? Lower center
Chapter 15: Stellar Remnants: White Dwarfs, Neutron Stars, and Black Holes
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White Dwarfs:
o The remains of low-mass stars (see Star Death HR diagram for complete process)
o Tiny in diameter (about same diameter as Earth)
o High density, retains 75% of original star’s mass
o Dim, only 1% as bright as our sun
o Temperature range from 4,000K to 25,000K, with 10,000 being typical
o Mainly consists of Carbon and Oxygen
o They have an escape velocity of around 6000 km/s
o Increasing the mass of a white dwarf results in a reduction in size
o The mass of a white dwarf is limited by its limiting mass, or Chandrasekhar limit.
Past this point, the star would collapse.
o If a white dwarf is in a binary system, its gravitational pull may pull in expelled
gas from its companion star. This new fuel expands rapidly upon fusing, causing a
nova.
o If enough gas is pulled into the white dwarf that it’s mass exceeds its
Chandrasekhar limit, the star collapses. During this collapse oxygen and carbon
fuses into silicon, which then fuses into nickel (which decays into cobalt, and then
iron). This releases enough energy to blow the star apart, known as a type Ia
supernova.
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Neutron Stars:
o If a large star (8+ solar masses) forms an iron core, when the star collapses and
creates a supernova the core does experience a sudden nuclear ignition and a
neutron star is instead born.
o This type of supernova is known as a type II supernova,
o Neutron stars are very small, typically having radii of only about 10 km in length.
o Neutron stars are extremely dense, typically having a mass of around 1 solar
masses or greater.
o They have an escape velocity of around 180,000 km/s
o Pulsars are rapidly rotating neutron stars with extremely powerful magnetic fields.
o Pulsars rotate extremely rapidly due to their tiny radius. Remember the “Ice skater
effect”.
o Pulsars magnetic fields are typically about 1 trillion times stronger than Earth’s
magnetic field.
o The emission created by the accelerating charges of a pulsar is called nonthermal
radiation because its properties depend on the charges' acceleration and on the
strength of the magnetic field, rather than on the temperature of a heated gas.
o Orbiting binary neutron stars can create gravitational waves, which, according to
general relativity, send waves of distortion in space and time.
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Black Holes
o A star of 20 solar masses, upon collapse, can compress its core so much that
pressure is unable to support it, and it totally collapses to form a black hole.
o A black hole’s escape velocity exceeds the speed of light
o The Schwarzschild Radius is the radius at which a body of mass M becomes a
black hole
o A collapsing star with a core mass of around 3 solar masses will result in a black
hole.
o The event horizon of a black hole is the point at which light cannot escape the
gravitational pull of said black hole
o When a black hole forms from a collapsing star, the solar matter of said star
crashes together to form a disk around the black hole. Extremely hot gas is ejected
in jets perpendicular to the disk. This type of collapse is known as a hypernova.
o Black holes in binary systems draw in gasses from the companion star, which
forms an accretion disk that rapidly orbits around the black hole. These gasses can
orbit at nearly the speed of light and reach temperatures of up to 10 million K.
This causes the gas to emit gamma and x-rays.
o We can pinpoint the position of black holes in binary systems by watching as its
x-ray producing accretion disk is eclipsed by its companion star. We can then
calculate the mass of the hidden object, and see if it is indeed a black hole.
o Hawking radiation is a form of electromagnetic wave that radiates from black
holes. It is created by quantum physical processes near the event horizon of a
black hole, and will slowly result in the dissipation of a black hole.
Chapter 15 Notes for Final Study Guide
White Dwarf:
Formed from the death of a low mass star blowing away its outer layer of hydrogen to expose its
core
Core stays hot for a long time but with no fuel source it cools and turns into a brown dwarf
Must be less than 1.4 solar masses otherwise it will collapse on itself and create a neutron star
If a dwarf star is in a binary system it can suck up from its companion star until it reaches critical
mass and spontaneous combustion occurs in an explosive event called a type 1A supernova
Neutron Star:
Formed when a star over 8 solar masses reaches the end of its life. As the star finishes fusing the
last fuel source it has it begins to fuse iron in its core and as the gravity begins to overwhelm the
internal pressure of the hot gas all of the material slams into the iron care smashing protons and
electrons together turning them into a highly dense ball of neutrons
Made from a core of 1.5-3 solar masses
About the size of Vancouver
Mass of 1 to several times that of the sun
Kept from collapsing farther by degeneracy pressure because only one neutron can occupy a
space at a time (Pauli exclusion principle)
Black Hole:
Formed from the collapse of a star more massive than 20 solar masses or rom a neutron star
collecting to much material to the point that it overwhelms it degeneracy pressure collapsing into
a black hole
Star must have a iron core of 3 or more solar masses
Black holes do not allow anything in their event horizon to escape this includes any type of
matter as well as photons
A black holes gravity warps space time
We know they are there by watching their interactions with things around them. Through
watching things orbit them at a safe distance away giving us the ability to do a mass calculation
using Kepler’s third law modified by Newton. Binary stars are another way we can view black
holes because as the material is sucked off of the companion star it is heated to 10 million K
when this happens it releases X-rays before it is sucked into its event horizon and then its
singularity
Ch 16
1. Draw a sketch of the Milky Way Galaxy and label its major components. Where is the
Sun in the Milky Way?
2. How big in diameter is the Milky Way Galaxy? How much mass (stars) does it contain?