SUN COURSE - SLIDE SHOW 1

1. SUN COURSE - SLIDE SHOW 1

2. For Centuries We Have Worshipped the Sun E.g., Greece -- Sun God: "Helios"

4. Why Study the Sun ? 1. Of great mathematical interest in own right 2. Influence on Earth 3. Important for Astronomy -- fundamental cosmic processes -- the only star can see closely 4. For me ... Many basic properties still a mystery So Sun is 1 of liveliest branches of mathematics Many research students attracted…

5. Why Does an Applied Mathematician Study the Sun ? Traditionally, close link A.M./Astron e.g., James Gregory (1638-1675) Invented Reflecting Telescope Co-founder of Calculus

6. James Gregory Lined up telescope along north-south line. Early pendulum clock Appointed 1st regius prof maths in St A 1668 (recommendation of Newton) Given Upper Hall of University Library as place of work Elected FRS 1668 (age 30)

7. Wanted use St Rule's tower for observations: picture (1680) But left in 1674 with words: "The affairs of the Observatory of St Andrews were in such a bad condition, the reason of which was, a prejudice the masters of the University did take at the mathematics. After this, my salary was also kept back from me, and scholars of most eminent rank were violently kept from me, contrary to their own wills, the masters persuading them that their brains were not able to endure it."

8. James Gregory: - wrote 1st text book on Calculus - discovered: -- General Binomial theorem -- Taylor expansions -- Ratio test for convergence of a series -- Series for sin x and tan x -- Integral of log x and sec x -- Differentiation is inverse to Integration -- How to use Change of Variable in integration

9. Solar Vital Statistics ? R = 10; 100; 1000 RE ? Age = 1000 y; 1,000,000 y; 1,000,000,000y ? Chemical composition Radius 700 Mm (1Mm = 1000 km) = 100 x Earth Age -- 4.6 billion years (1b = 1000 million) 91% H, 8.9% He, + minor elements (O, C, N, Fe ...) Ball of gas held together by gravity ? Mean distance from Earth 93 million miles = 215 Ro

10. 1. Overall Structure Interior --> Core, Convection zone Atmosphere --> Photosphere, Chromosphere, Corona

13. Core -- Energy is Generated Temperature = 15 million K Pressure 200 billion times atmospheric pressure Natural fusion reactor [-- but Gentle]

15. Convection Zone - turbulent motions Top - visible surface of Sun: PHOTOSPHERE ("Light")

16. 2. Photosphere Temperature = 6000 K Sunspots -- in pairs(why ?) Rotates -- not like solid ball -- Equator 26 days -- Poles 37 days Close-up : Covered with turbulent convection cells -- "Granulation" Same as porridge or mackerel sky

17. Photosphere Covered with turbulent convection cells: “Granulation” (1 Mm) “Supergranulation” (15 Mm)

19. Amazing images at from La Palmathis year

20. In close-up:points, flowers, ribbons(created by magnetic fields)

24. 3. SUNS POTS

29. Existence known since 350 BC (Greece), 28 BC (China) Sunspots In West, no ref until 850 AD; Galileo (1611) Umbra Penumbra Site strong B. Flux tube - ?? Model

30. Dark because Cool 1600K cooler than photo. ?? Why cool

32. LATEST IDEAS on NATURE of SUNSPOTS Introduction Observed over 2000 years Hale (1908): strong B (3000G cf mean q Sun 3G) Outside sunspots: strong small-scale convn (gran, 1 Mm) + weak larger-scale convn (supergran, 15 Mm) Umbra - (15 Mm, B strong, vertical) dark -- cool, inhibition of convection

33. Penumbra (40 Mm, B intermed, inclined) radial light/dark filaments

34. NEW THEORY - Weiss et al (2004)

35. Scharmer et al (2004) New Swedish Solar Telescope on La Palma (Canaries)

37. StunningImage(Swedish telescope, La Palma) Penumbral structure created by B Close-up of penumbra -> new surprises:

39. Points moving along lanes; Bright flows in/out; Strange dark cores