Solar and Solar-Terrestrial Physics Physics 363 Time: 3:15-4:45, Tuesday, Thursday

1. Solar and Solar-Terrestrial Physics • Physics 363 • Time: 3:15-4:45, Tuesday, Thursday • Place: Hewlett , room 103 • Instructor: Alexander Kosovichev • e-mail: sasha@quake.stanford.edu • Phone: 723-7667 • Office: Physics and Astrophysics, room 128 • URL: http://sun.stanford.edu/~sasha/PHYS363 • Grades: bi- weekly assessments + presentations

2. Lecture Plan • Jan. 8, Tuesday. Introduction: The Sun as a star. General properties, place in the Hertzsprung-Russell diagram. Distance, mass, radius, luminosity, composition, age, evolution, spectral energy distribution. "Big problems": solar neutrinos, rotation, dynamo, magnetic energy release, coronal heating. • Jan. 10, Thursday. Internal structure I. Stellar Scaling Laws. Standard model. Evolution. Nuclear reactions. Equation of state. Radiative transfer. • Jan. 15, Tuesday. Internal structure II. Stability. Convective transfer. Non-standard models. Solar neutrinos, neutrino transitions, MSW effect. • Jan. 17, Thursday. Solar oscillations. Observations. Theory of p-, g-, and r-modes. Excitation mechanisms. • Jan. 22, Tuesday. Helioseismology I. Variational principle, perturbation theory. Inversions, sound speed and rotation inferences. • Jan. 24, Thursday. Helioseismology II. Local-area helioseismology, ring-diagrams, acoustic imaging, time-distance tomography. • Jan. 29, Tuesday. Convection. Granulation, supergranulation, giant cells. Blue shift, models. Energy balance. Superadiabatic layer. Rotational and magnetic effects. Numerical simulations. • Jan. 31, Thursday. Differential rotation. Observations. Heliographic coordinates. Oblateness, quadrupole moment, test of the general relativity. Rotational history. Models of differential rotation. • Feb. 5, Tuesday. Solar MHD. MHD equations, Alfven and magneto-acoustic waves. Instabilities. Shocks.

3. Feb. 7, Thursday. Dynamo The solar cycle, global magnetism. "Magnetic carpet". Mean-field electrodynamics, dynamo models. • Feb. 12, Tuesday. Magnetic energy release. Reconnection. Particle acceleration. Observations. Theories of reconnection, current sheets, MHD and plasma instabilities. Acceleration mechanisms. • Feb. 14, Thursday. Solar atmosphere. The structure of the solar atmosphere, photosphere, chromosphere, corona. Transition region. Chromospheric network, filaments, prominences, spicules. • Feb. 19, Tuesday. Sunspots. Active regions. Flux tubes. Observations. Static models. Flows, Evershed effect. Formation and decay. Theories of emerging flux tubes, magnetic buoyancy. • Feb. 21, Thursday. Flares. Observations. Radiation, radio-, X-, and gamma-rays. Energetic particles. Thin- and thick-target models, evaporation, heat conduction. Radiative and MHD shocks. Moreton waves, "sunquakes". • Feb. 26, Tuesday. Corona. CME. Observations, eclipses. White light corona, Thompson scattering. Coronal heating, heat conduction. Large-scale structure, change with the solar cycle. Coronal mass ejections, shocks. • Feb. 28, Thursday. Solar wind. Observations. Expansion, Parker’s model, high- and low-speed wind. Composition, first-ionization potential effect. Sector structure, current sheet. Geomagnetic effects. Space weather.

4. March 4, Tuesday. Space weather. Interaction of solar wind with the Earth's magnetosphere and planets. Geomagnetic effects. Space weather • March 6, Thursday.Tools for solar observations I. Solar telescopes. Resolution, MTF, seeing. High resolution telescopes. Spectrographs. • March 11, Tuesday.Tools for solar observations II. Measurements of the line shift. Magnetic fields and polarimetry. • March 13, Thursday.Tools for solar observations III. Solar space missions: SOHO, TRACE, STEREO, Hinode, SDO. Neutrino telescopes.

5. Books • Stix, M. 2002, The Sun: An Introduction, (Berlin: Springer) • Cox, A.N., Lingston, W.C., Matthews, M.S., 1991, Solar Interior and Atmosphere (Tucson, University of Arizona) • Zirin, H. 1988, Astrophysics of the Sun (Cambridge Univ. Press) • Bahcall J.N. 1989, Neutrino Astrophysics (Cambridge Univ. Press) • Foukal, P. 1990, Solar Astrophysics (New York: Wiley) • Priest, E.R. 1982, Solar Magnetohydrodynamics (Dordrecht: Reidel) • Golub, L., and Pasachoff, J.M. 1997, The Solar Corona (Cambridge Univ. Press) • Sturrock, P. (ed.) 1986, Physics of the Sun, (Kluwer). • Aschwanden, M. J., Physics of the Solar Corona, Springer, 2006

6. Essay Topics. • Solar diameter, oblateness and gravitational quadrupole moment • Solar neutrino problem. • Predictions of the solar cycle. • Helioseismic inverse problem for structure. • Helioseismic inverse problem for rotation • Excitation of solar oscillations. • Solar convection and turbulence. • Mechanism of differential rotation. • Solar tachocline. • Magnetic reconnection. • MHD shocks and Moreton waves. • Dynamo models. • Acceleration mechanisms in solar flares. • Coronal mass ejections. • Mechanisms of coronal heating. • Coronal seismology. • Acceleration of solar wind. • Waves in magnetosphere

7. 22,000 stars from Hipparcos catalog General Properties of the Sun.Hertzsprung-Russel Diagram. • 1911-13, Ejnar Hertzsprung and Henry Norris Russell independently developed H-R diagram • Horizontal axis - spectral type (or, equivalently, color index or surface temperature) • Vertical axis - absolute magnitude (or luminosity) • Data points define definite regions, suggesting common relationship exists for stars composing region. Each region represents stage in evolution of stars. • The place of a star on the H-R diagram also tells us about its radius, energy generation and transport, periods and growth rates of pulsations, rotation rate, stellar activity, X-ray coronas, etc. • Sun is G2 main-sequence star. Lies roughly in middle of diagram among what are referred to as yellow dwarfs. Sun Hertzsprung-Russel Diagram. Numbers in the main-sequence band are stellar masses in units of the solar mass. Dotted lines correspond to constant radius in units of the solar radius.RW - radiatively driven wind.

8. Overall properties

9. Distance

10. Distance - II Kepler’s law Triangulation

11. The Sun's angular size varies from 31' 27.7" to 32' 31.9" during the course of a year.

12. Sun’s rotation axis is inclined by 7.25 degrees to the ecliptic

13. Mass

14. Radius

16. Oblateness

17. Quadrupole moment

18. Composition

19. Luminosity Absorption in the Earth’s atmosphere. The edge of the shaded area marks the height where the radiation is reduced to 1/2 of its original strength. UV - ultraviolet; V- visible; IR - infrared.

20. Irradiance The composite total irradiance from 1977 to 1999. Note the variation with the solar activity cycle of order 0.1%

21. Effective temperature

22. Spectral energy distribution

23. Solar irradiance spectrum 1 nm = 10 A 1 Angstrom = 10-10 m = 10-8 cm = 0.1 nm

24. Temperature & Density Structure of the “Solar Atmosphere” ) -3 7 10 16 10 Corona 3 millionK n H 1 millionK 6 10 T 14 10 Temperature (K) 5 10 Transition Region Total Hydrogen Density (cm 12 10 60,000K Chromosphere 4 10 10 10 6,000K 8 10 3 10 2 3 4 5 10 10 10 10 Height Above Photosphere (km)

25. Visible spectrum

26. Infrared spectrum The infrared spectral irradiance.

27. Radio spectrum

28. UV spectrum

29. EUV and X-ray spectrum

30. Soft X-ray from GOES satellite

31. Black body radiation Black body spectrum depends only on temperature

33. Temperature & Density Structure of the “Solar Atmosphere” ) -3 7 10 16 10 Corona 3 millionK n H 1 millionK 6 10 T 14 10 Temperature (K) 5 10 Transition Region Total Hydrogen Density (cm 12 10 60,000K Chromosphere 4 10 10 10 6,000K 8 10 3 10 2 3 4 5 10 10 10 10 Height Above Photosphere (km)

34. Visible solar spectrum with absorption (Fraunhofer) lines

36. Color indices

37. Real-time solar images http://sohowww.nascom.nasa.gov/ http://www.bbso.njit.edu/cgi-bin/LatestImages http://www.raben.com/maps/

38. White-light Image SOHO/MDI Continuum 6768 A

39. Magneto- gram magnetogram

40. H-alpha H-alpha 6563 A

41. Ca II K line Chromo- sphere Ca II K 3933 A

42. EUV He II 304 Å SOHO EIT He II 304A

43. EUV Fe IX/X 171 Å SOHO EIT Fe IX/X 171 A

44. Fe XII 195 A

45. Fe XV 284 A