Solar Data

1. Solar Physics and Sun-Earth Connection (introduction)Samuel DanagoulianNC A&T State UniversityTeacher’s Workshop, 1-27-05

2. Solar Data • Solar radius = 695,990 km = 432,470 mi = 109 Earth radii • Solar mass = 1.989 1030 kg = 4.376 1030 lb = 333,000 Earth masses • Solar luminosity (energy output of the Sun) = 3.846 1033 erg/s • Surface temperature = 5770 K = 10,400 ºF • Surface density = 2.07 10-7 g/cm3 = 1.6 10-4 Air density • Surface composition = 70% H, 28% He, 2% (C, N, O, ...) by mass

3. Solar Data (cont.) • Central temperature = 15,600,000 K = 28,000,000 ºF • Central density = 150 g/cm3 = 8 × Gold density • Central composition = 35% H, 63% He, 2% (C, N, O, ...) by mass • Solar age = 4.57 109 yr • Solar Rotation: period 27 days • Solar Cycles: ~11 years, ~22 years

4. Solar Structure 6000 K 15x106 K X-rays and UV, 1x106 K Magnetic filed causes formation of Sunspots, flares, mass ejections

5. Introduction to Nuclear Physics • Molecular force is Electromagnetic: (long range) Atoms are held together by a dipole force which has an origin of Electro-Magnetism • Atom = nucleus + (orbiting electrons) The force between nucleus and electrons has EM origin • Nucleus = few nucleons together (protonsand neutrons) The force between nucleons is STRONG (nuclear) which is present and attractive only at short distances. Between two protons, in addition, there is Electromagnetic force, which is repulsive. In order to create a stable nucleus, one needs to dilute the charged nuclear matter (protons) with neutral particles (neutrons). STRONG force is 137 times stronger than EM force.

6. Particle Zoo PARTICLES SIZEMASS(AMU) • Molecules10-8 m • Atoms10-11 m1-260 • Nucleus <10-14 m1-260 • Heavy Particles (BARIONS) • Nucleons: (p, n), hyperons 10-15 m1 – 1.5 • Light Particles (MESONS) <10-15 m • regular, strange, charm, top, bottom 0.14 – 10 -- QUARKS (u, d, s, c, t, b) <10-18 m0.001 - 5 • GAUGE Particles (g, W+-, Z0, g) 0 - 100 • LEPTONS<10-18 m • Electron, mu, tau (e,m,t) 0.0005 - 2 • Neutrino - electron, mu, tau ( ne , nm , nt ) 0 (?) GAUGE particles provide interaction between particles and quarks

7. Nuclear Binding Energyhttp://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html

8. Solar Energy • Thermonuclear reactions, pp-chain (98% of energy) p+p  d+e++ne (neutrino energy is 0.42 MeV) p+e- +p  d+ne (1.44 MeV) p+d  3He+g 3He+3He4He+2p 3He+p4He+e++ne (18.8 MeV) 3He+4He7Be+g 7Be+e- 7Li+g (0.38, 0.86 MeV) 7Li+ p  8Be+g 8Be24He

9. Solar Structure 6000 K 15x106 K X-rays and UV, 1x106 K Magnetic filed causes formation of Sunspots, flares, mass ejections

10. Modeling of Solar Mechanism • Mechanical and thermal equilibrium • Pressure gradient balances gravitational force • Solar energy radiation is balanced bythe thermonuclear energy of the core • Energy transportation from the core to the surface: • to the 1/3 of the radius from the surface, where the opacity is high (Radiative envelope); • Convective envelope • Radiation to the outer space through Photosphere and Chromosphere • Numerical Integration of the process: the constraints: • Observed mass, radius, luminosity and ratio of chemical abundances by mass.

11. Solar Neutrino puzzle • Chlorine experiment (Davis, 1964-1999) 615 tons Liquid perchloroethylene (Homestake gold mine in South Dakota ) 37Cl+n37Ar+e-(threshold=0.814 MeV) Prediction from Solar Model Calculations: (7.6+-1.2) SNU Experimental result: (2.56+-0.23) SNU • Japanese Experiment (Kamioka mine, 1996) 680 tons of water. Super-K: n+e-  n+e- (threshold=5.5 MeV, e- cherenkov light in the water). Experimental result: low rate, flavour change • GALLEX, SAGE, GNO (1999, Gallium experiments) Experimental result: low rate • SNO (Sudbury Neutrino Observatory, heavy water experiment) Experimental result: neutrino flavour change

12. SNO results confirmed Super-K results onne count rate. • There are three types of neutrinos: ne nmand nt. Neutrino oscillates from one flavour to another during it’s long journey to the Earth. • KamLAND experiment (2003, detection of neutrinos from the reactor): confirmed the results of SNO and calculated the parameter responsible for the mixing of flavors.

13. Solar Flares • http://science.nasa.gov/ssl/pad/solar/sunturn.htm

14. Coronal Loops

15. Coronal Loops • Coronal loops are found around sunspots and in active regions. These structures are associated with the closed magnetic field lines that connect magnetic regions on the solar surface. Many coronal loops last for days or weeks but most change quite rapidly • Some loops, however, are associated with solar flares and are visible for much shorter periods. These loops contain denser material than their surroundings. The three-dimensional structure and the dynamics of these loops is an area of active research.

16. Solar Flares SOHO

17. Solar Flares (cont)

18. Solar Flare • is defined as a sudden and intense variation in solar brightness. The solar magnetic energy is suddenly released. Radiation occurs in the entire electromagnetic spectrum, (radio waves to X- and g -rays). The first solar flare recorded in astronomical literature was on September 1, 1859.

19. Polar Plumes SOHO

20. Polar Plumes • Polar plumes are long thin streamers that project outward from the Sun's north and south poles. These structures are associated with the "open" magnetic field lines at the Sun's poles. The plumes are formed by the action of the solar wind in much the same way as the peaks on the helmet streamers.

21. Solar Flares, Solar Wind SOHO

22. Solar Wind

23. Solar Wind

24. Coronal Holes SOHO

25. Coronal Holes • Coronal holes are regions where the corona is dark. These features were discovered with X-ray telescopes above the earth's atmosphere observing the solar disc. Coronal holes are associated with "open" magnetic field lines and are often found at the Sun's poles. The high-speed solar wind is known to originate in coronal holes.

26. Solar Activity

27. Solar Activity and Geomagnetic storm

29. Aurora

30. Aurora • Is caused by high energy particles (mainly electrons) interacting with the Earth's atmosphere over the North Pole. Due to the interaction of electrons with atoms of the air, an excitation of latter takes place following by the emission of the light quanta which removes the excitation of the atom.

31. Aurora(cont.) • This process is called scintillation of the air due to the passage of electrons through it. The spectrum of the light emission is in the UV-visible range, depending of the nature of the gas and maximum energy of the particles. The intensity of the emission depends on the intensity of electrons.

32. Aurora from the space

33. Aurora (cont.) • The effect of interaction of many electrons with atoms results in the Aurora that can be clearly seen during some nights in the higher latitude close to the North Pole. Since electrons mainly originate from the sun, the intensity depends greatly on the status of the solar activity.

34. Aurora (cont.) • However, the energy of electrons is not enough high to excite the air atoms unless they are accelerated in the way to the earth's atmosphere. The acceleration occurs during the disturbance of the geomagnetic field of the Earth, during geomagnetic storm.

35. Aurora (cont.) • The idea is that the geomagnetic field is responding to a disturbance from the Sun due to magnetic explosions on the Sun's corona and coronal mass ejection towards the Earth. The geomagnetic field of the Earth changes due to the flux of magnetic field, releasing energy and thereby accelerating electrons and other particles to high energies.

36. Aurora (cont.) • These particles are bent in the geomagnetic field to spiral along the magnetic field lines. Some amount of particles end up in the upper part of the earth's atmosphere causing the auroral mechanism to begin. http://www.oulu.fi/~spaceweb/textbook/auroras.html http://www.geo.mtu.edu/weather/aurora/images/aurora/jan.curtis

37. Aurora (cont.)

38. Happy New Year !