Your SlideShare is downloading. ×
0
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
A1 15 Our Sun
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

A1 15 Our Sun

1,990

Published on

Miller's Astronomy 1 lecture notes on our Sun

Miller's Astronomy 1 lecture notes on our Sun

Published in: Education, Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
1,990
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
100
Comments
0
Likes
1
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. The Solar Interior LACC: §14.3, 15.2, 15.3 • Know what powers the sun • Understand the Solar Neutrino Problem • Know the Solar interior An attempt to answer the “big questions”: what is the sun? how does it effect us? Thursday, April 15, 2010 1
  • 2. The Sun: Wow! Sheet Energy generated in the Sun's core takes a million years to reach its surface. Every second 700 million tons (1/(3 billion billionth) of the sun’s total mass) of hydrogen are converted into helium ash. In the process 5 million tons of pure energy is released; therefore, as time goes on, the Sun is getting lighter. Mass (tons) 2.19x1027 Mass (Earth = 1) 332,830 Principal chemistry (1.) Equatorial radius (km) 695,000 Hydrogen 92.10% Equatorial radius (Earth = 1) 108.97 Helium 7.80% Mean density (gm/cm 3) 1.41 Oxygen 0.061% Rotational period (days)! 25-36* Carbon 0.030% Escape velocity (km/sec) 618.02 Nitrogen 0.084% Luminosity (ergs/sec) 3.83x1033 Neon 0.076% Magnitude (Vo) -26.8 Iron 0.0037% Mean surface temperature! 10,800°F Silicon 0.0031% Core temperature! 27,000,000°F Magnesium 0.0024% Core density (gm/cm3) 150 Sulfur 0.0015% Core pressure (atm) 340,000,000,000 All others 0.0015% Age (billion years) 4.5 1. % by # of atoms abundances * The Sun's period of rotation at the surface varies from approximately 25 days at the equator to 36 days at the poles. Deep down, below the convective zone, everything appears to rotate with a period of 27 days. http://www.solarviews.com/eng/sun.htm Thursday, April 15, 2010 2
  • 3. The Proton-Proton Chain http://astro.unl.edu/classaction/loader.html?filename=animations/sunsolarenergy/ fusion01.swf&movieid=fusion01&width=550&height=550&version=6.0.0 Thursday, April 15, 2010 3
  • 4. The Atom, e.g. He 4 http://www.bio.miami.edu/~cmallery/150/chemistry/c8.2x5.helium.jpg Thursday, April 15, 2010 4
  • 5. Subatomic Particles of Interest Particle Symbols Charge Mass Protons p, p+, 1H, H+ +1 1.0073 Neutrons n, n0 0 1.0087 Electrons e, e+, β+ -1 0.0005 Positron e- , β - +1 0.0005 Neutrino ν 0 0? Gamma Ray γ 0 0 Alpha Particle α, 4He, He2+ +2 4.0015 Thursday, April 15, 2010 5
  • 6. p-p Chain: Energy Production The evidence is strong that the sun is "burning" H to make He: 4H + 2e- --> He4 + 2 neutrinos + 6 photons In this reaction, the final particles have less internal energy than the starting particles. Since energy is conserved, the extra energy is released as energy of motion of the nuclei and electrons in the solar gas, the production of photons [pure energy] and, finally, the energy of the neutrinos, which just zip right out of the Sun. That is the gas gets hotter and has lots of photons (and neutrinos). The amount of energy involved is 26 MeV (26 million eV) each time the reaction above happens. (By comparison, CH4 + 2O2 --> CO2 + 2H2O results in 5.5 eV of energy.) Why do we think that this is what goes on? • Energy output of millions of eV per reaction is needed if the Sun has been producing energy at the observed rate over billions of years. • The reactions exist. (They have been studied in the laboratory.) • There is a consistent step-by-step theory for the reaction. Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA soper@bovine.uoregon.edu http://zebu.uoregon.edu/~soper/Sun/fusion.html Thursday, April 15, 2010 6
  • 7. Solar Neutrino Problem Super- Kamiokande, a neutrino detector in Japan, holds 50,000 tons of ultrapure water surrounded by light tubes. http://www.scidacreview.org/0601/html/astro.html Thursday, April 15, 2010 7
  • 8. Solar Neutrino Problem Over the years scientists have considered two possible explanations of the solar neutrino problem: 1. Perhaps we don't understand the Sun well enough. Maybe a better theory of the internal structure of the Sun would predict fewer neutrinos, in agreement with the measurements. 2. Perhaps we don't understand neutrinos well enough; maybe they have some features beyond the standard theory of neutrinos that account for the problem. http://www.cora.nwra.com/~werne/eos/text/neutrino.html Thursday, April 15, 2010 8
  • 9. The Solar Neutrino Problem Particles in the Standard Model of particle physics: The Standard Model contains 3 neutrinos of definite flavor, and a set of corresponding anti- particles. http://conferences.fnal.gov/lp2003/forthepublic/neutrinos/index.html Thursday, April 15, 2010 9
  • 10. Hydrostatic Equilibrium http://physics.uoregon.edu/~jimbrau/astr122/Notes/Chapter16.html Thursday, April 15, 2010 10
  • 11. Solar Interior http://sprg.ssl.berkeley.edu/%7Eabbett/sun1.html Thursday, April 15, 2010 11
  • 12. Solar Interior The photons produced in nuclear reactions take about a million years to move from the core to the surface. The photons scatter off the dense gas particles in the interior and move about a centimeter between collisions. In each collision they transfer some of their energy to the gas particles. By the time photons reach the photosphere, the gamma rays have become photons of much lower energy---visible light photons. Because the photons now reaching the surface were produced about a million years ago, they tell us about the conditions in the core as it was a million years ago. The other particle produced in nuclear reactions has a less tortuous path out of the core. A neutrino is a massless (or very nearly massless) particle that rarely interacts with ordinary matter. Neutrinos travel extremely fast---the speed of light if they have zero mass or very close to the speed of light if they have a small mass. Because they travel so fast and interact so rarely with matter, neutrinos pass from the core of the Sun to the surface in only two seconds. They take less than 8.5 minutes to travel the distance from the Sun to the Earth. If you could detect them, the neutrinos would tell you about the conditions in the Sun's core as it was only 8.5 minutes ago (much more current information than the photons!). http://www.astronomynotes.com/starsun/s4.htm Thursday, April 15, 2010 12
  • 13. Solar Core http://fas.org/irp/imint/docs/rst/Sect20/A5a.html Thursday, April 15, 2010 13
  • 14. Solar Interior Core Radiation • p-p chain occurs • photons travel • convection • vacuum, gasses Radiative zone Convection • photon random walk • bulk fluid flow • radiation • liquid, gasses Convection zone Conduction • convection cells • individual molecules collide • convection • solids Thursday, April 15, 2010 14
  • 15. The Solar Interior LACC: §14.3, 15.2, 15.3 • Know what powers the sun: Nuclear Fusion, the p-p chain, 4H + 2e- --> He4 + 2 ν + 6 γ • Understand the Solar Neutrino Problem: It seems that neutrinos can change flavor • Know the Solar interior: core, radiative zone, convection zone, photosphere An attempt to answer the “big questions”: what is the sun? how does it effect us? Thursday, April 15, 2010 15
  • 16. HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed. • Ch 15, p354: #4 • Ch 14: Tutorial Quizzes accessible from: http:// www.brookscole.com/cgi-brookscole/course_products_bc.pl? fid=M20b&product_isbn_issn=9780495017899&discipline_number=19 • Ch 15: Image Analysis Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/ course_products_bc.pl? fid=M20b&product_isbn_issn=9780495017899&discipline_number=19 Due beginning of next class period. Thursday, April 15, 2010 16
  • 17. Solar Surface and Atmosphere LACC: §14.3, 15.2, 15.3 • Know the sun’s atmosphere • Know solar surface features • Know how the sun affects the earth An attempt to answer the “big questions”: what is the sun? how does it effect us? Thursday, April 15, 2010 17
  • 18. Solar Atmosphere K = Kelvin °C = Celsius °F = Fahrenheit K = °C + 273.15 °F = 1.8°C + 32° So, at high temperature, °F ≅ 1.8°C At very high temperatures, °F ≅ 1.8K http://rst.gsfc.nasa.gov/Sect20/A5a.html Thursday, April 15, 2010 18
  • 19. Solar Features http://ircamera.as.arizona.edu/NatSci102/lectures/sun.htm Thursday, April 15, 2010 19
  • 20. Solar Features: Sunspots http://www.astro.wisc.edu/ http://starchild.gsfc.nasa.gov/docs/ ~sparke/ast103/ StarChild/questions/question17.html lecture11.html Granules are individual convection cells. Thursday, April 15, 2010 20
  • 21. Solar Features: Sunspots Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are "dark" because they are cooler than their surroundings. A large sunspot might have a central temperature of 4,000 K (about 3,700° C or 6,700° F), much lower than the 5,800 K (about 5,500° C or 10,000° F) temperature of the adjacent photosphere. Sunspots are only dark in contrast to the bright face of the Sun. If you could cut an average sunspot out of the Sun and place it elsewhere in the night sky, it would be about as bright as a full moon. Sunspots have a lighter outer section called the penumbra, and a darker central region named the umbra. Sunspots form over periods lasting from days to weeks, and can persist for weeks or even months http://www.windows.ucar.edu/ before dissipating. The average number of spots visible tour/link=/sun/images/ on the face of the Sun is not constant, but varies in a sunspots_earth_size_big_jpg_i multi-year cycle. Historical records of sunspot counts, mage.html&edu=high which go back hundreds of years, verify that this sunspot cycle has an average period of roughly eleven years. http://www.windows.ucar.edu/tour/link=/sun/ atmosphere/sunspots.html&edu=high Thursday, April 15, 2010 21
  • 22. Solar Features: Sunspot Cycle Although astronomers have observed the fairly regular rise and fall of sunspot counts in this 11-year cycle for several centuries, there have also been disruptions in this pattern. The largest well-documented disruption was an era that lasted from about 1645 to 1715 during which almost no sunspots were seen. This long lull is known as the Maunder Minimum. Curiously, Europe and parts of North America were struck by spells of remarkably cold weather at roughly the same time. http://www.windows.ucar.edu/tour/link=/sun/activity/solar_variation.html Thursday, April 15, 2010 22
  • 23. Solar Features: Sunspots--Cause Sunspots are magnetic -- they occur in pairs where one is a north pole while the other is a south pole. Every 11 years, the more western parts of sunspot pairs will change from magnetic N to magnetic S (or vice versa). (From Chaisson & McMillan, Astronomy Today) http://ircamera.as.arizona.edu/NatSci102/ lectures/sun.htm Thursday, April 15, 2010 23
  • 24. Solar Features: Sunspots and Magnetism Every 11 years the sun’s magnetic field snaps back to situation #1. But, when it snaps back, the North and South magnetic poles will be reversed. So the sunspot cycle is every 11 years, but the solar magnetic field cycle is every 22 years. http://www.windows.ucar.edu/tour/link=/sun/atmosphere/ sunspot_form_jpg_image.html&edu=high Thursday, April 15, 2010 24
  • 25. Solar Features: Prominences (and Filaments) One of the most spectacular solar sights is a prominence. A solar prominence is a cloud of solar gas held above the Sun's surface by the Sun's magnetic field. Last month, NASA's Sun-orbiting SOHO spacecraft imaged an impressively large prominence hovering over the surface, pictured above. The Earth would easily fit under the hovering curtain of hot gas. A quiescent prominence typically lasts about a month, and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System. Although somehow related to the Sun's changing magnetic field, the energy mechanism that creates and sustains a Solar prominence is still a topic of research. http://apod.nasa.gov/apod/ap040330.html Thursday, April 15, 2010 25
  • 26. Solar Features: Prominences (and Filaments) Hot gas frequently erupts from the Sun. One such eruption produced the glowing filament pictured above, which was captured in 2000 July by the Earth-orbiting TRACE satellite. The filament, although small compared to the overall size of the Sun, measures over 100,000 kilometers in height, so that the entire Earth could easily fit into its outstretched arms. Gas in the filament is funneled by the complex and changing magnetic field of the Sun. After lifting off from the Sun's surface, most of the filamentary gas will eventually fall back. http://antwrp.gsfc.nasa.gov/apod/ap040725.html Thursday, April 15, 2010 26
  • 27. Solar Features: Prominences (and Filaments) http://www.veoh.com/browse/videos/category/technology/watch/v2191746WPa6CtKC Thursday, April 15, 2010 27
  • 28. Flares vs Filament (Prominence) Solar flare (171Å) Solar flare (1600Å) Solar flare (white light) The two images on the left were taken on 25 June 2000, around 07:37UT (the images were rotated, so that north is to the left). The image on the left shows a filament in the process of being ejected from the Sun, with cool (dark) and hot (bright; around 1.5 million degrees) material at opposite ends of the long, nearly vertical structure. http://soi.stanford.edu/results/SolPhys200/Schrijver/TRACEpodoverview.html Thursday, April 15, 2010 28
  • 29. Solar Features: Flares Solar flares are essentially huge explosions on the Sun. Flares occur when intense magnetic fields on the Sun become too tangled. Like a rubber band that snaps when it is twisted too far, the tangled magnetic fields release energy when they "snap". Solar flares emit huge bursts of electromagnetic radiation, including X-rays, ultraviolet radiation, visible light, and radio waves. The energy emitted by a solar flare is more than a million times greater than the energy from a volcanic explosion on Earth! Although solar flares can be visible in white light, they are often more readily noticed via their bright X-ray and ultraviolet emissions. Coronal mass ejections often accompany solar flares, though scientists are still trying to determine exactly how the two phenomena are related. Solar flares burst forth from the intense magnetic fields in the vicinity of active regions on the Sun. Solar flares are most common during times of peak solar activity, the "solar max" years of the sunspot cycle. http://www.windows.ucar.edu/tour/link=/ sun/atmosphere/solar_flares.html&edu=high Thursday, April 15, 2010 29
  • 30. Coronal Mass Ejection http://www.windows.ucar.edu/tour/link=/sun/images/aug1980cme_jpg_image.html Thursday, April 15, 2010 30
  • 31. Coronal Mass Ejection "Without warning, the relatively calm solar atmosphere can be torn asunder by sudden outbursts of a scale unknown on Earth. Catastrophic events of incredible energy...stretch up to halfway across the visible solar surface, suddenly and unpredictably open up and expel their contents, defying the Sun's enormous gravity." (Sun, Earth, and Sky by Kenneth R. Lang) These catastrophic events that the author is speaking about are coronal mass ejections (CME's). Coronal mass ejections are explosions in the Sun's corona that spew out solar particles. The CME's typically disrupt helmet streamers in the solar corona. As much as 1x1013 (10 trillion) kilograms of material can be ejected into the solar wind. Coronal mass ejections propagate out in the solar wind, where they may encounter the Earth and influence geomagnetic activity. CME's are believed to be driven by energy release from the solar magnetic field. How this energy release occurs, and the relationship between different types of solar activity, is one of the many puzzles facing solar physicists today. http://www.windows.ucar.edu/tour/link=/sun/cmes.html&edu=high Thursday, April 15, 2010 31
  • 32. Magnetic Storms CME's can seriously disrupt the Earth's environment. Intense radiation from the Sun, which arrives only 8 minutes after being released, can alter the Earth's outer atmosphere, disrupting long-distance radio communications and deteriorating satellite orbits. Very energetic particles pushed along by the shock wave of the CME can endanger astronauts or fry satellite electronics. These energetic particles arrive at the Earth (or Moon) about an hour later. The actual coronal mass ejection arrives at the Earth one to four days after the initial eruption, resulting in strong geomagnetic storms, aurorae and electrical power blackouts. "Thus, the Sun's sudden and unexpected outbursts remain as unpredictable as most human passions. They just keep on happening, and even seem to be necessary to purge the Sun of pent- up frustration and to relieve it of twisted, contorted magnetism." (Kenneth R. Lang, Sun, Earth and Sky) http://www.windows.ucar.edu/tour/ link=/sun/cmes.html&edu=high http://ess.nrcan.gc.ca/rrnh-rran/proj3_e.php Thursday, April 15, 2010 32
  • 33. Solar Wind The Sun is flinging 1 million tons of matter out into space every second! We call this material solar wind. Once the solar wind is blown into space, the particles travel at supersonic speeds of 200-800 km/sec! These particles travel all the way past Pluto and do not slow down until they reach the termination shock within the heliosphere. The Heliosphere is the entire region of space influenced by the Sun. The solar wind plasma is very thin. Near the Earth, the plasma is only about 6 particles per cubic centimeter. So, even though the wind travels SUPER fast, it wouldn't even ruffle your hair if you were to stand in it because it's so thin! But, it is responsible for such unusual things as: • auroral lights • fueling magnetospheric storms The particles of the solar wind, and the Sun's magnetic field (IMF) are stuck together, therefore the solar wind carries the IMF (interplanetary magnetic field) with it into space. http://www.windows.ucar.edu/tour/link=/sun/solar_wind.html&edu=mid Thursday, April 15, 2010 33
  • 34. Aurora http://www.nasa.gov/centers/goddard/ news/topstory/2005/dueling_auroras.html http://apod.nasa.gov/apod/ap060329.html Thursday, April 15, 2010 34
  • 35. Solar Surface and Atmosphere LACC: §14.3, 15.2, 15.3 • Know the sun’s atmosphere: photosphere (visible), chromosphere (reddish), corona (2 million Kelvin), solar wind (e- and p+’s) • Know solar surface features: granules, sunspots, prominences, flares, coronal mass ejections • Know how the sun affects the earth: CME disruption of electronics, aurora An attempt to answer the “big questions”: what is the sun? how does it effect us? Thursday, April 15, 2010 35
  • 36. HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed. • Ch 14, p354: #5--Prominence, Flare, Coronal Mass Ejection (mention energy, size, and time) • Ch 15: Image Analysis Quizzes accessible from: http://www.brookscole.com/cgi-brookscole/ course_products_bc.pl? fid=M20b&product_isbn_issn=9780495017899&discipline_number=19 • 16, 17: Tutorial Quizzes accessible from: http:// www.brookscole.com/cgi-brookscole/course_products_bc.pl? fid=M20b&product_isbn_issn=9780495017899&discipline_number=19 Due beginning of next class period. Thursday, April 15, 2010 36

×