1. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Welcome to the The First Joint Arizona/NSO Summer School June 11-16, NSO Sac Peak Observatory, NM

2. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 List of Topics and Lecturers Helioseismology –Rachel Howe, NSO, Tucson –Rudi Komm, NSO, Tucson Solar Interior –Gordon Petrie, NSO, Tucson Radiative Transfer –Han Uitenbroek, NSO, Sac Peak Solar Magnetohydrodynamics –Randy Jokipii, UofA, Tucson Photospheric and Chromospheric Magnetic Fields –K.S. Balasubramanian (Bala), NSO, Sac Peak Solar-Energetic Particles –Joe Giacalone, UofA, Tucson Space Weather –Tom Bogan, NCAR, Boulder

3. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 List of Activities Computer software programs –RASL/DASL CDs and workbooks –xsolar (Chris Russell, UCLA) Solar wind, interplanetary magnetic fields –Helioseismology application widget (Rachel Howe) Solar viewing through Hα telescopes –Outside of visitor center Poster viewing/discussion

4. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 List of Other Activities Monday – reception at the director’s house Tuesday – White Sands picnic Wednesday – –Tour of NSO facilities, –Community BBQ Thursday – Pizza Night / Star Party

5. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The Physics of the Sun

6. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Why Study the Sun ? Influence on Earth Important for Astronomy –Only star that we can see closely The source of many interesting and important physics problems For Me? –Many basic properties are a mystery! dynamo, coronal heating, source of high-energy particles, etc. –Space radiation environment, space weather, acceleration of high- energy charged particles

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8. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Source of the Sun’s Internal Energy: p-p chain is dominate for the Sun; also CNO chain

9. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Solar Structure: The Standard Solar Model Theoretical model used to determine the physical properties of the Sun’s interior Hydrostatic and thermal equilibrium –A big ball of gas held together by gravity + radiative diffusion Can add convection, but this is difficult (simple approach – mixing- length theory) Nuclear reaction rates and opacities are needed Boundary conditions are tricky – need to use an iterative approach

10. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Solar Oscillations Waves can propagate through the Sun causing a variety of vibrations –Like sound waves These are used to infer pressures, densities, chemical compositions, and rotation rates within the Sun –Constraints on solar models Helioseismology

11. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Turbulent convective motions cause overturning (bubbling) motions inside the Sun. –These are responsible for the granulation pattern seen on the Sun’s surface. –Rayleigh-Bénard convection

12. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Recent High- resolution Images of granulation

13. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The photosphere About 5700K –Coolest region of the Sun (coldest in sunspots) Sunspots (usually in pairs) Variety of convection cells (granulation, supergranulation, etc.) Limb Darkening

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17. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The Chromosphere Above the photosphere is a layer of less dense but higher temperature gases called the chromosphere “Color Sphere” characterized by spikes of rising gas Spicules extend upward from the photosphere into the chromosphere along the boundaries of supergranules

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19. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The Corona The outermost layer of the solar atmosphere, the corona, is made of very high-temperature gases at extremely low density The solar corona blends into the solar wind at great distances from the Sun Because the corona is very hot, it is best viewed in the x-ray part of the spectrum What heats the corona remains an open question!

20. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Emission Spectra in the UV Far UV To the far right of this plot is the extreme UV (soft X-ray) Near UV Dupree et al., ApJ, 1973

21. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 SOHO/EIT image at 195 Angstroms (FeXII)

22. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Sunspots Existence known since 350 BC (Greece), 28 BC (China) Lower temperature Umbra and penumbra Associated with Intense magnetic fields –Zeeman effect

23. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The Babcock model and Solar Dynamo

24. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The 11-year Sunspot Cycle Number of Sunspots versus time – they come and go every 11 years Number of Sunspots versus latitude – forms a “butterfly pattern”

25. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The Sun and Earth’s Climate: The Maunder Minimum Complete absence of sunspots for 50 years corresponds to a mini ice age There is a loose correlation between global man temperature and sunspots

26. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Magnetism is the Key to Understanding the Sun

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28. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Coronal loops expand from the surface of the Sun following a solar explosion (solar flare) on April 21, 2002 TRACE movie

29. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The Buildup and release of magnetic field energy CMEs and Flares –A solar flare is a brief eruption of hot, ionized gases from a sunspot group –A coronal mass ejection (CME) is much larger Geomagnetic storms High-Energy Particles (Space Radiation) Halloween 2003 storms

30. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 The Sun is the Most Important Particle Accelerator in the Solar System

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32. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Aurora in Tucson

33. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 SOHO/LASCO (C3) Coronagraph “Halloween” solar storms of 2003

34. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Propagating Shocks Analogy with sonic booms Efficient particle accelerators Radiation Environment and Space Weather

35. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 My research has shown that the angle between the shock propagation direction and the magnetic field determines the maximum energy in the particle events Perpendicular shocks  high- energy particles

36. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Perpendicular Shocks in the solar atmosphere

37. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 Analogy to Cosmic Rays and Supernove remants: Supernova Remnant 1006 – Chandra image

38. UofA/NSO Summer SchoolIntroduction to the Sun 6/17/06 To Finish