DOC PREVIEW
TAMU ASTR 101 - Lecture14_2009C

This preview shows page 1-2-3-4-5-32-33-34-35-65-66-67-68-69 out of 69 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 69 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Copyright © 2009 Pearson Education, Inc.Chapter 10Our StarCopyright © 2009 Pearson Education, Inc.FissionBig nucleus splits intosmaller pieces.(Nuclear power plants)FusionSmall nuclei stick togetherto make a bigger one.(Sun, stars)Copyright © 2009 Pearson Education, Inc.High temperaturesenable nuclearfusion to happen inthe core.Copyright © 2009 Pearson Education, Inc.The Sun releases energy by fusing four hydrogen nucleiinto one helium nucleus.Copyright © 2009 Pearson Education, Inc.IN4 protonsOUT4He nucleus2 gamma rays2 positrons2 neutrinosTotal mass is 0.7% lower.Copyright © 2009 Pearson Education, Inc.Thought QuestionWhat would happen inside the Sun if a slight rise incore temperature led to a rapid rise in fusion energy?A. The core would expand and heat up slightly.B. The core would expand and cool.C. The Sun would blow up like a hydrogen bomb.Copyright © 2009 Pearson Education, Inc.Thought QuestionWhat would happen inside the Sun if a slight rise incore temperature led to a rapid rise in fusion energy?A. The core would expand and heat up slightly.B. The core would expand and cool.C. The Sun would blow up like a hydrogen bomb.Solar thermostat keeps the rate of fusion steadyCopyright © 2009 Pearson Education, Inc.Solar ThermostatDecline in core temperaturecauses fusion rate to drop, socore contracts and heats up.Rise in core temperaturecauses fusion rate to rise, socore expands and cools down.Copyright © 2009 Pearson Education, Inc.How does the energy from fusionget out of the Sun?Copyright © 2009 Pearson Education, Inc.Energy gradually leaks out of the radiation zone in theform of randomly bouncing photons.Copyright © 2009 Pearson Education, Inc.Convection (rising hot gas) takes energy to the surface.Copyright © 2009 Pearson Education, Inc.Bright blobs on photosphere where hot gas reaches the surfaceCopyright © 2009 Pearson Education, Inc.How do we know what ishappening inside the Sun?Copyright © 2009 Pearson Education, Inc.We learn about the inside of the Sun by:• making mathematical models• observing solar vibrations• observing solar neutrinosCopyright © 2009 Pearson Education, Inc.Patterns ofvibration on thesurface tell usabout what theSun is likeinside.Copyright © 2009 Pearson Education, Inc.Data on solarvibrationsagree withmathematicalmodels ofsolar interior.Copyright © 2009 Pearson Education, Inc.Neutrinoscreated duringfusion flydirectly throughthe Sun.Observations ofthese solarneutrinos can tellus what’shappening in thecore.Copyright © 2009 Pearson Education, Inc.Solar neutrinoproblem:Early searches forsolar neutrinos failedto find the predictednumber.Copyright © 2009 Pearson Education, Inc.Solar neutrinoproblem:Early searches forsolar neutrinos failedto find the predictednumber.More recentobservations find theright number ofneutrinos, but somehave changed form.Copyright © 2009 Pearson Education, Inc.What have we learned?• How does nuclear fusion occur in the Sun?— The core’s extreme temperature and densityare just right for the nuclear fusion ofhydrogen to helium through the proton–protonchain.— Gravitational equilibrium acts as a thermostatto regulate the core temperature because thefusion rate is very sensitive to temperature.Copyright © 2009 Pearson Education, Inc.What have we learned?• How does the energy from fusion get out ofthe Sun?—Randomly bouncing photons carry it throughthe radiation zone.—The rising of hot plasma carries energythrough the convection zone to thephotosphere.• How do we know what is happening insidethe Sun?—Mathematical models agree with observationsof solar vibrations and solar neutrinos.Copyright © 2009 Pearson Education, Inc.10.3 The Sun–Earth ConnectionOur goals for learning:• What causes solar activity?• How does solar activity affect humans?• How does solar activity vary with time?Copyright © 2009 Pearson Education, Inc.What causes solar activity?Copyright © 2009 Pearson Education, Inc.Solar activity is like “weather” on Earth.• Sunspots• Solar flares• Solar prominencesAll these phenomena are related to magneticfields.Copyright © 2009 Pearson Education, Inc.Sunspots…Are coolerthan otherparts of theSun’s surface(4000 K)Are regionswith strongmagneticfieldsCopyright © 2009 Pearson Education, Inc.ZeemanEffectWe canmeasuremagneticfields insunspots byobserving thesplitting ofspectral lines.Copyright © 2009 Pearson Education, Inc.Charged particles spiral along magnetic field lines.Copyright © 2009 Pearson Education, Inc.Loops of bright gas often connect sunspot pairs.Copyright © 2009 Pearson Education, Inc.Magneticactivity causessolar flares thatsend bursts ofX-rays andchargedparticles intospace.Copyright © 2009 Pearson Education, Inc.Magneticactivity alsocauses solarprominencesthat erupt highabove the Sun’ssurface.Copyright © 2009 Pearson Education, Inc.The coronaappears brightin X-ray photosin places wheremagnetic fieldstrap hot gas.Copyright © 2009 Pearson Education, Inc.How does solar activity affecthumans?Copyright © 2009 Pearson Education, Inc.Coronal massejections sendbursts of energeticcharged particlesout through thesolar system.Copyright © 2009 Pearson Education, Inc.Charged particles streaming from the Sun can disruptelectrical power grids and disable communications satellites.Copyright © 2009 Pearson Education, Inc.How does solar activity varywith time?Copyright © 2009 Pearson Education, Inc.The number of sunspots rises and falls in 11-year cycles.Copyright © 2009 Pearson Education, Inc.The sunspot cycle has something to do with the windingand twisting of the Sun’s magnetic field.Copyright © 2009 Pearson Education, Inc.What have we learned?• What causes solar activity?—The stretching and twisting of magnetic fieldlines near the Sun’s surface causes solaractivity.• How does solar activity affect humans?—Bursts of charged particles from the Sun candisrupt communications, satellites, andelectrical power generation.• How does solar activity vary with time?—Activity rises and falls in 11-year cycles.Copyright © 2009 Pearson Education, Inc.11.1 Properties of StarsOur goals for learning:• How do we measure stellar luminosities?• How do we measure stellar temperatures?• How do we measure stellar masses?Copyright © 2009 Pearson Education, Inc.How do we measure stellarluminosities?Copyright © 2009 Pearson Education, Inc.Brightness of a star depends on both distance and luminosity.Copyright © 2009 Pearson Education,


View Full Document

TAMU ASTR 101 - Lecture14_2009C

Documents in this Course
Lecture14

Lecture14

56 pages

Lecture17

Lecture17

35 pages

lecture3

lecture3

65 pages

Lecture02

Lecture02

40 pages

Lecture16

Lecture16

35 pages

Lecture27

Lecture27

69 pages

Lecture03

Lecture03

26 pages

astronomy

astronomy

90 pages

Lecture23

Lecture23

47 pages

Lecture15

Lecture15

45 pages

Lecture24

Lecture24

64 pages

Lecture25

Lecture25

22 pages

Lecture22

Lecture22

48 pages

Lecture02

Lecture02

25 pages

Lecture03

Lecture03

32 pages

Lecture05

Lecture05

28 pages

Lecture19

Lecture19

72 pages

Load more
Download Lecture14_2009C
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Lecture14_2009C and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Lecture14_2009C 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?