© 2006 pearson prentice hall lecture outlines powerpoint chapter 24 earth science 11e...

© 2006 Pearson Prentice Hall

Lecture Outlines PowerPoint

Chapter 24

Earth Science 11e

Tarbuck/Lutgens

Modified for educational purposes only

By S. Koziol 12-8-2010

Earth Science, 11eEarth Science, 11e

Beyond Our Beyond Our Solar SystemSolar System

Chapter 24Chapter 24

24.1 Properties of stars 24.1 Properties of stars Distance Distance

• Measuring a star's distance can be very Measuring a star's distance can be very difficultdifficult

• Stellar parallaxStellar parallax • Used for measuring distance to a starUsed for measuring distance to a star• Apparent shift in a star's position due to the Apparent shift in a star's position due to the

orbital motion of Earthorbital motion of Earth• Measured as an angleMeasured as an angle• Near stars have the largest parallaxNear stars have the largest parallax• Largest parallax is less than one second of arc Largest parallax is less than one second of arc

24. 1 Properties of stars24. 1 Properties of stars(continued)

Distance Distance • Distances to the stars are very largeDistances to the stars are very large• Units of measurementUnits of measurement

• Kilometers or astronomical units are too Kilometers or astronomical units are too cumbersome to usecumbersome to use

• Light-yearLight-year is used most often is used most often• Distance that light travels in 1 yearDistance that light travels in 1 year• One light-year is 9.5 trillion km (5.8 trillion One light-year is 9.5 trillion km (5.8 trillion

miles)miles)• Other methods for measuring distance are Other methods for measuring distance are

also used also used

24. 1 Properties of stars 24. 1 Properties of stars (continued)

Stellar brightness Stellar brightness • Controlled by three factorsControlled by three factors

• SizeSize• TemperatureTemperature• DistanceDistance

• Magnitude Magnitude • Measure of a star's brightnessMeasure of a star's brightness

24.1 Properties of stars24.1 Properties of stars(continued)

Stellar brightness Stellar brightness • Magnitude Magnitude

• Two types of measurement Two types of measurement • Apparent magnitudeApparent magnitude

• Brightness when a star is viewed from Brightness when a star is viewed from EarthEarth

• Decreases with distanceDecreases with distance• Numbers are used to designate Numbers are used to designate

magnitudes - dim stars have large magnitudes - dim stars have large numbers and negative numbers are also numbers and negative numbers are also used used


Stellar brightness Stellar brightness • Magnitude Magnitude

• Two types of measurement Two types of measurement • Absolute magnitude Absolute magnitude

• "True" or intrinsic brightness of a star"True" or intrinsic brightness of a star• Brightness at a standard distance of Brightness at a standard distance of

32.6 light-years32.6 light-years• Most stars' absolute magnitudes are Most stars' absolute magnitudes are

between -5 and +15 between -5 and +15

24.1 Properties of stars 24.1 Properties of stars (continued)

Color and temperature Color and temperature • Hot star Hot star

• Temperature above 30,000 KTemperature above 30,000 K• Emits short-wavelength lightEmits short-wavelength light• Appears blue Appears blue

• Cool star Cool star • Temperature less than 3000 KTemperature less than 3000 K• Emits longer-wavelength lightEmits longer-wavelength light• Appears redAppears red


Color and temperature Color and temperature • Between 5000 and 6000 KBetween 5000 and 6000 K

• Stars appear yellowStars appear yellow• e.g., Sune.g., Sun

Binary stars and stellar mass Binary stars and stellar mass • Binary starsBinary stars

• Two stars orbiting one another Two stars orbiting one another • Stars are held together by mutual gravitationStars are held together by mutual gravitation• Both orbit around a common center of mass Both orbit around a common center of mass


Binary stars and stellar mass Binary stars and stellar mass • Binary starsBinary stars

• Visual binaries are resolved telescopicallyVisual binaries are resolved telescopically• More than 50% of the stars in the universe are More than 50% of the stars in the universe are

binary starsbinary stars• Used to determine stellar massUsed to determine stellar mass

• Stellar massStellar mass• Determined using binary stars – the center of Determined using binary stars – the center of

mass is closest to the most massive star mass is closest to the most massive star

Binary stars Binary stars orbit each orbit each

other around other around their common their common

center of center of massmass

Figure 24.4


Binary stars and stellar mass Binary stars and stellar mass • Stellar massStellar mass

• Mass of most stars is between one-tenth and Mass of most stars is between one-tenth and fifty times the mass of the Sun fifty times the mass of the Sun

24.1 Hertzsprung-Russell 24.1 Hertzsprung-Russell diagram diagram

Shows the relation between stellar Shows the relation between stellar • Brightness (absolute magnitude) andBrightness (absolute magnitude) and• TemperatureTemperature

Diagram is made by plotting (graphing) Diagram is made by plotting (graphing) each star's each star's • Luminosity Luminosity (brightness) and(brightness) and• Temperature Temperature

24.1 Hertzsprung-Russell 24.1 Hertzsprung-Russell diagram diagram (continued)

Parts of an H-R diagram Parts of an H-R diagram • Main-sequence starsMain-sequence stars

• 90% of all stars90% of all stars• Band through the center of the H-R diagramBand through the center of the H-R diagram• Sun is in the main-sequenceSun is in the main-sequence

• Giants Giants (or red giants) (or red giants) • Very luminousVery luminous• LargeLarge• Upper-right on the H-R diagram Upper-right on the H-R diagram

24.1 Hertzsprung-Russell 24.1 Hertzsprung-Russell diagram diagram (continued)

Parts of an H-R diagram Parts of an H-R diagram • Giants Giants (or red giants) (or red giants)

• Very large giants are called supergiantsVery large giants are called supergiants• Only a few percent of all starsOnly a few percent of all stars

• White dwarfsWhite dwarfs• Fainter than main-sequence starsFainter than main-sequence stars• Small (approximate the size of Earth)Small (approximate the size of Earth)• Lower-central area on the H-R diagramLower-central area on the H-R diagram• Not all are white in colorNot all are white in color• Perhaps 10% of all starsPerhaps 10% of all stars

Idealized Hertzsprung-Idealized Hertzsprung-Russell diagramRussell diagram

Figure 24.5

Quiz BreakQuiz Break

24.2 Variable stars 24.2 Variable stars

Stars that fluctuate in brightnessStars that fluctuate in brightness Types of variable stars Types of variable stars

• Pulsating variablesPulsating variables • Fluctuate regularly in brightnessFluctuate regularly in brightness• Expand and contract in sizeExpand and contract in size

• Eruptive variablesEruptive variables• Explosive eventExplosive event• Sudden brighteningSudden brightening• Called a Called a novanova

24.2 Interstellar matter 24.2 Interstellar matter

Between the stars is "the vacuum of Between the stars is "the vacuum of space"space"

NebulaNebula• Cloud of dust and gasesCloud of dust and gases• Two major types of nebulaeTwo major types of nebulae

• Bright nebula Bright nebula • Glows if it close to a very hot starGlows if it close to a very hot star• Two types of bright nebulaeTwo types of bright nebulae

• Emission nebula Emission nebula • Reflection nebulaReflection nebula

The Orion Nebula is a well-The Orion Nebula is a well-known emission nebulaknown emission nebula

Figure 24.8

A faint blue reflection nebula in A faint blue reflection nebula in the Pleiades star clusterthe Pleiades star cluster

Figure 24.9

24.2 Interstellar matter 24.2 Interstellar matter (continued)

NebulaNebula• Two major types of nebulaeTwo major types of nebulae

• Dark nebula Dark nebula • Not close to any bright starNot close to any bright star• Appear darkAppear dark• Contains the material that forms stars and Contains the material that forms stars and

planetsplanets

24.2 Stellar evolution 24.2 Stellar evolution

Stars exist because of gravityStars exist because of gravity Two opposing forces in a star are Two opposing forces in a star are

• Gravity – contractsGravity – contracts• Thermal nuclear energy – expandsThermal nuclear energy – expands

StagesStages• BirthBirth

• In dark, cool, interstellar cloudsIn dark, cool, interstellar clouds• Gravity contracts the cloudGravity contracts the cloud• Temperature risesTemperature rises• Radiates long-wavelength (red) lightRadiates long-wavelength (red) light• Becomes a Becomes a protostar protostar

24.2 Stellar evolution 24.2 Stellar evolution (continued)

StagesStages• Protostar Protostar

• Gravitational contraction of gaseous cloud Gravitational contraction of gaseous cloud continuescontinues

• Core reaches 10 million KCore reaches 10 million K• Hydrogen nuclei fuseHydrogen nuclei fuse

• Become helium nucleiBecome helium nuclei• Process is called Process is called hydrogen burning hydrogen burning

• Energy is releasedEnergy is released• Outward pressure increasesOutward pressure increases• Outward pressure balanced by gravity pulling inOutward pressure balanced by gravity pulling in• Star becomes a stable main-sequence starStar becomes a stable main-sequence star


StagesStages• Main-sequence stageMain-sequence stage

• Stars age at different rates Stars age at different rates • Massive stars use fuel faster and exist for Massive stars use fuel faster and exist for

only a few million yearsonly a few million years• Small stars use fuel slowly and exist for Small stars use fuel slowly and exist for

perhaps hundreds of billions of yearsperhaps hundreds of billions of years

• 90% of a star's life is in the main-sequence90% of a star's life is in the main-sequence


StagesStages• Red giant stage Red giant stage

• Hydrogen burning migrates outwardHydrogen burning migrates outward• Star's outer envelope expandsStar's outer envelope expands

• Surface coolsSurface cools• Surface becomes red Surface becomes red

• Core is collapsing as helium is converted to Core is collapsing as helium is converted to carboncarbon

• Eventually all nuclear fuel is usedEventually all nuclear fuel is used• Gravity squeezes the star Gravity squeezes the star


StagesStages• Burnout and death Burnout and death

• Final stage depends on massFinal stage depends on mass• PossibilitiesPossibilities

• Low-mass starLow-mass star• 0.5 solar mass0.5 solar mass• Red giant collapsesRed giant collapses• Becomes a Becomes a white dwarfwhite dwarf

24.2 Evolutionary stages of 24.2 Evolutionary stages of low mass starslow mass stars

Figure 24.12 A




• Medium-mass star Medium-mass star • Between 0.5 and 3 solar massesBetween 0.5 and 3 solar masses• Red giant collapsesRed giant collapses• Planetary nebulaPlanetary nebula forms forms • Becomes a Becomes a white dwarfwhite dwarf

24.2 Evolutionary stages of 24.2 Evolutionary stages of medium mass starsmedium mass stars

Figure 24.12 B

H-R diagram showing H-R diagram showing stellar evolutionstellar evolution

Figure 24.11




• Massive star Massive star • Over 3 solar massesOver 3 solar masses• Short life spanShort life span• Terminates in a brilliant explosion called Terminates in a brilliant explosion called

a a supernovasupernova• Interior condenses Interior condenses • May produce a hot, dense object that is May produce a hot, dense object that is

either a either a neutron starneutron star or a or a black holeblack hole

24.2 Evolutionary stages of 24.2 Evolutionary stages of massive starsmassive stars

Figure 24.12 C

24.2 Stellar remnants 24.2 Stellar remnants

White dwarfWhite dwarf• Small (some no larger than Earth)Small (some no larger than Earth)• DenseDense

• Can be more massive than the SunCan be more massive than the Sun• Spoonful weighs several tonsSpoonful weighs several tons• Atoms take up less spaceAtoms take up less space

• Electrons displaced inwardElectrons displaced inward• Called degenerate matterCalled degenerate matter

• Hot surfaceHot surface• Cools to become a black dwarf Cools to become a black dwarf

24.2 Stellar remnants 24.2 Stellar remnants (continued)

Neutron star Neutron star • Forms from a more massive star Forms from a more massive star

• Star has more gravityStar has more gravity• Squeezes itself smaller Squeezes itself smaller

• Remnant of a supernovaRemnant of a supernova• Gravitational force collapses atoms Gravitational force collapses atoms

• Electrons combine with protons to produce Electrons combine with protons to produce neutronsneutrons

• Small size Small size


Neutron star Neutron star • Pea size sample Pea size sample

• Weighs 100 million tonsWeighs 100 million tons• Same density as an atomic nucleusSame density as an atomic nucleus

• Strong magnetic fieldStrong magnetic field• First one discovered in early 1970sFirst one discovered in early 1970s

• PulsarPulsar (pulsating radio source) (pulsating radio source)• Found in the Crab nebula (remnant of an A.D. Found in the Crab nebula (remnant of an A.D.

1054 supernova) 1054 supernova)

Crab Nebula in the Crab Nebula in the constellation Taurusconstellation Taurus

Figure 24.14


Black hole Black hole • More dense than a neutron starMore dense than a neutron star• Intense surface gravity lets no light escapeIntense surface gravity lets no light escape• As matter is pulled into itAs matter is pulled into it

• Becomes very hotBecomes very hot• Emits x-raysEmits x-rays

• Likely candidate is Cygnus X-1, a strong x-Likely candidate is Cygnus X-1, a strong x-ray source ray source

24.3 Galaxies 24.3 Galaxies

Milky Way galaxy Milky Way galaxy • StructureStructure

• Determined by using radio telescopesDetermined by using radio telescopes• Large spiral galaxy Large spiral galaxy

• About 100,000 light-years wideAbout 100,000 light-years wide• Thickness at the galactic nucleus is about Thickness at the galactic nucleus is about

10,000 light-years 10,000 light-years • Three spiral arms of starsThree spiral arms of stars• Sun is 30,000 light-years from the center Sun is 30,000 light-years from the center

Face-on view of the Face-on view of the Milk Way GalaxyMilk Way Galaxy

Figure 24.18 A

Edge-on view of the Edge-on view of the Milk Way GalaxyMilk Way Galaxy

Figure 24.18 B

24.3 Galaxies 24.3 Galaxies (continued)

Milky Way galaxy Milky Way galaxy • RotationRotation

• Around the galactic nucleusAround the galactic nucleus• Outermost stars move the slowestOutermost stars move the slowest• Sun rotates around the galactic nucleus once Sun rotates around the galactic nucleus once

about every 200 million yearsabout every 200 million years

• Halo surrounds the galactic disk Halo surrounds the galactic disk • SphericalSpherical• Very tenuous gasVery tenuous gas• Numerous globular clusters Numerous globular clusters

24.3 Galaxies 24.3 Galaxies (continued) Other galaxiesOther galaxies

• Existence was first proposed in mid-1700s Existence was first proposed in mid-1700s by Immanuel Kantby Immanuel Kant

• Four basic types of galaxies Four basic types of galaxies • Spiral galaxySpiral galaxy

• Arms extending from nucleusArms extending from nucleus• About 30% of all galaxiesAbout 30% of all galaxies• Large diameter of 20,000 to 125,000 light Large diameter of 20,000 to 125,000 light

yearsyears• Contains both young and old starsContains both young and old stars• e.g., Milky Waye.g., Milky Way

Great Galaxy, a spiral galaxy, in Great Galaxy, a spiral galaxy, in the constellation Andromeda the constellation Andromeda

Figure 24.20


• Four basic types of galaxies Four basic types of galaxies • Barred spiral galaxy Barred spiral galaxy

• Stars arranged in the shape of a barStars arranged in the shape of a bar• Generally quite largeGenerally quite large• About 10% of all galaxiesAbout 10% of all galaxies

• Elliptical galaxy Elliptical galaxy • Ellipsoidal shapeEllipsoidal shape• About 60% of all galaxiesAbout 60% of all galaxies• Most are smaller than spiral galaxies; Most are smaller than spiral galaxies;

however, they are also the largest known however, they are also the largest known galaxies galaxies

A barred spiral galaxyA barred spiral galaxy

Figure 24.22


• Four basic types of galaxies Four basic types of galaxies • Irregular galaxy Irregular galaxy

• Lacks symmetryLacks symmetry• About 10% of all galaxiesAbout 10% of all galaxies• Contains mostly young starsContains mostly young stars• e.g., Magellanic Clouds e.g., Magellanic Clouds

24.3 Galaxies 24.3 Galaxies (continued) Galactic cluster Galactic cluster

• Group of galaxiesGroup of galaxies• Some contain thousands of galaxiesSome contain thousands of galaxies• Local GroupLocal Group

• Our own group of galaxiesOur own group of galaxies• Contains at least 28 galaxiesContains at least 28 galaxies

• SuperclusterSupercluster• Huge swarm of galaxiesHuge swarm of galaxies• May be the largest entity in the universe May be the largest entity in the universe

24.4 Red shifts 24.4 Red shifts

Doppler effectDoppler effect• Change in the wavelength of light emitted Change in the wavelength of light emitted

by an object due to its motionby an object due to its motion • Movement away stretches the wavelength Movement away stretches the wavelength

• Longer wavelengthLonger wavelength• Light appears redderLight appears redder

• Movement toward “squeezes” the wavelengthMovement toward “squeezes” the wavelength• Shorter wavelengthShorter wavelength• Light shifted toward the blueLight shifted toward the blue

24.4 Red shifts 24.4 Red shifts (continued)

Doppler effectDoppler effect• Amount of the Doppler shift indicates the Amount of the Doppler shift indicates the

rate of movement rate of movement • Large Doppler shift indicates a high velocityLarge Doppler shift indicates a high velocity• Small Doppler shift indicates a lower velocitySmall Doppler shift indicates a lower velocity

Expanding universe Expanding universe • Most galaxies exhibit a red Doppler shift Most galaxies exhibit a red Doppler shift

• Moving away Moving away

Raisin bread analogy of an Raisin bread analogy of an expanding universeexpanding universe

Figure 24.24

24.4 Red shifts 24.4 Red shifts (continued)

Expanding universe Expanding universe • Most galaxies exhibit a Most galaxies exhibit a red Doppler shiftred Doppler shift

• Far galaxiesFar galaxies• Exhibit the greatest shiftExhibit the greatest shift• Greater velocity Greater velocity

• Discovered in 1929 by Edwin HubbleDiscovered in 1929 by Edwin Hubble• Hubble's LawHubble's Law – the recessional speed of – the recessional speed of

galaxies is proportional to their distancegalaxies is proportional to their distance• Accounts for red shifts Accounts for red shifts

24.4 Big Bang theory 24.4 Big Bang theory

Accounts for galaxies moving away Accounts for galaxies moving away from usfrom us

Universe was once confined to a "ball" Universe was once confined to a "ball" that was that was • SupermassiveSupermassive• DenseDense• Hot Hot

24.4 Big Bang theory 24.4 Big Bang theory (continued)

Big Bang marks the inception of the Big Bang marks the inception of the universe universe • Occurred about 15 billion years agoOccurred about 15 billion years ago• All matter and space was createdAll matter and space was created

Matter is moving outward Matter is moving outward Fate of the universe Fate of the universe

• Two possibilities Two possibilities • Universe will last foreverUniverse will last forever• Outward expansion sill stop and gravitational; Outward expansion sill stop and gravitational;

contraction will followcontraction will follow

24.4 Big Bang theory 24.4 Big Bang theory (continued)

Fate of the universe Fate of the universe • Final fate depends on the average density Final fate depends on the average density

of the universe of the universe • If the density is more than the critical density, If the density is more than the critical density,

then the universe would contractthen the universe would contract• Current estimates point to less then the critical Current estimates point to less then the critical

density and predict an ever-expanding, or density and predict an ever-expanding, or open, universe open, universe

Chapter 24Test Chapter 24Test GuidanceGuidance

You will be responsible on the test for answering 3 of the following 6 You will be responsible on the test for answering 3 of the following 6 questions.questions.

1.1. What causes the difference between a star’s apparent What causes the difference between a star’s apparent magnitude and it absolute magnitude. magnitude and it absolute magnitude.

2.2. List and explain the three factors that control the apparent List and explain the three factors that control the apparent brightness of a star as seen from Earth.brightness of a star as seen from Earth.

3.3. Describe how binary stars are used to determine stellar mass.Describe how binary stars are used to determine stellar mass.

4.4. List and describe the four basic types of galaxies.List and describe the four basic types of galaxies.

5.5. What is Hubble’s Law, please explain in detail.What is Hubble’s Law, please explain in detail.

6.6. Briefly describe the Big Bang Theory Briefly describe the Big Bang Theory (not the TV show(not the TV show))..

End of Chapter 24End of Chapter 24

© 2006 pearson prentice hall lecture outlines powerpoint chapter 24 earth science 11e...

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