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How the Sun Shines

How the Sun Shines. Zachary Robinson Phys 406. Overview. What creates the sun’s energy? Composition of Sun Fusion in the Sun (and other stars) Creation of the elements Studying the sun with helioseismology What is it? How is it used? Studying the sun through neutrino detection

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How the Sun Shines

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  1. How the Sun Shines Zachary Robinson Phys 406

  2. Overview • What creates the sun’s energy? • Composition of Sun • Fusion in the Sun (and other stars) • Creation of the elements • Studying the sun with helioseismology • What is it? • How is it used? • Studying the sun through neutrino detection • Solar neutrino problem • SNO

  3. Composition of the Sun • 74% Hydrogen • 24% Helium • 2% Trace Elements http://www.nasa.gov/images/content/449080main_img_feature_1650_4x3_946-710.jpg

  4. Major Fusion Reaction in Sun Hydrogen Recycling: Images from: http://www.nobelprize.org/nobel_prizes/physics/articles/fusion/

  5. More Fusion in the Sun Images from: http://www.nobelprize.org/nobel_prizes/physics/articles/fusion/

  6. The CNO Cycle Positron http://www.nobelprize.org/nobel_prizes/physics/articles/fusion/

  7. Creation of the Elements via Fusion • Video from NOVA’s “Origins” mini-series: • http://www.youtube.com/watch?feature=player_embedded&v=neMEo8ZrwuI

  8. Helioseismology • What is it? • Study of the interior of the sun via observations of sound waves on its surface • How does it work? • Sun acts as a spherical resonant cavity for acoustic waves • Oscillations from acoustic waves result in small Doppler shifts of spectrum lines

  9. Helioseismology • How is it used? • By numerically solving solar models we can determine information about the sun • For example: Solar structure, chemical composition, temperature at different depths http://www.stat.berkeley.edu/~stark/Seminars/Aaas/helio.htm

  10. Neutrino Detection • Detecting the proper amount of neutrinos from the sun would verify fusion theories • Solar Neutrino Problem (SNP): • Solar neutrino measurements have yielded inconsistent and perplexing results • Presently the measured flux of neutrinos is significantly less than the expected output from the sun’s fusion reactions! • SAGE and GALLEX detect only 60 to 70% of expected http://www.chemistry.bnl.gov/SciandTech/SN/

  11. Explanations for the SNP • The sun’s reaction mechanisms are not correctly understood • This would be a huge blow to models which have otherwise been very successful • No satisfactory modifications have been proposed • Experiments could be performed incorrectly • Reaction rates in the Sun could be lower than calculations predict • Something could happen to the neutrinos in transit to earth…

  12. Neutrino Flavors • Three types of neutrinos: • Electron, muon, tau • The sun should only produce electron neutrinos • Until recently, neutrino detectors could only detect electron neutrinos • MSW effect: Sun’s high mass densities enhance the flavor oscillations of neutrinos conferences.fnal.gov

  13. Sudbury Neutrino Observatory (SNO) • Detector that could detect all three flavors • Built 6800 feet underground in Canada • Cherenkov detector using 1000 metric tons of heavy water (D2O) • All air, water, and materials in detector are extremely pure to reduce background noise from radioactive elements • Collecting data since 1999 http://www.sno.phy.queensu.ca/images/man_on_deck.GIF

  14. Sources "Fusion Process of the Sun." Grant Chronicles. GrantChronicles.com, 2009. Web. 28 Nov 2011. <http://www.grantchronicles.com/astro01.htm>. Guenther, D.B. "Age of the Sun." Astrophysics Journal. 339. (1989): 1156-1159. Print. Graps, Amara. "Helioseismology." Stanford.edu. Stanford University, 19 Feb 2009. Web. 6 Dec 2011. <http://soi.stanford.edu/results/heliowhat.html>. "How the Sun Shines". Nobelprize.org. 30 Nov 2011 http://www.nobelprize.org/nobel_prizes/physics/articles/fusion/ Stark, P.B.. "Sounding the Sun: Helioseismology." AAAS Seminars. University of California, Apr 2011. Web. 3 Dec 2011. <http://www.stat.berkeley.edu/~stark/Seminars/Aaas/helio.htm> Strobel, Nick. "Neutrino." The Sun and Stellar Structure. AstronomyNotes.com, 12 Jun 2010. Web. 3 Dec 2011. <http://www.astronomynotes.com/starsun/s4.htm> "The SNO Homepage." The Sudbury Neutrino Observatory. The SNO Institute, 21 Apr 2011. Web. 24 Nov 2011. <http://www.sno.phy.queensu.ca/>.

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