SUN COURSE - SLIDE SHOW 1

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

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

Many basic properties still a mystery 4. For me ...

Why Study the Sun ?

So Sun is 1 of liveliest branches of mathematics

Many research students attracted…

WhyDoes an Applied Mathematician Study the Sun ?

Traditionally, close link A.M./Astron

e.g., James Gregory (1638-1675)

Co-founder of Calculus

Invented Reflecting Telescope

James Gregory

Elected FRS 1668 (age 30)Lined up telescope along north-south line.

Early pendulum clockAppointed 1st regius prof maths in St A 1668

(recommendation of Newton)Given Upper Hall of University Library as place of work

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."

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

Solar Vital Statistics

Ball of gas held together by gravity

? R = 10; 100; 1000 RE

Radius 700 Mm (1Mm = 1000 km) = 100 x Earth

? Age = 1000 y; 1,000,000 y; 1,000,000,000y

Age -- 4.6 billion years (1b = 1000 million)

? Chemical composition

91% H, 8.9% He,+ minor elements (O, C, N, Fe ...)

? Mean distance from Earth 93 million miles = 215 Ro

Interior --> Core, Convection zone

Atmosphere --> Photosphere, Chromosphere, Corona

1. Overall Structure

Core -- Energy is Generated

Temperature = 15 million K

Pressure 200 billion times atmospheric pressure

Natural fusion reactor [-- but Gentle]

Convection Zone - turbulent motions

Top - visible surface of Sun: PHOTOSPHERE ("Light")

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

2. Photosphere

Covered with turbulent

convection cells: “Granulation”

(1 Mm)“Supergranulation”

(15 Mm)

Photosphere

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

Amazing images at

from La Palmathis year

In close-up:

points, flowers, ribbons

(created by magnetic

fields)

3. SUNS POTS

SunspotsExistence known since 350 BC (Greece), 28 BC (China)

In West, no ref until 850 AD;

Galileo (1611)

Site strong B.

Umbra

Penumbra

Flux tube - ?? Model

Dark because Cool

1600K cooler than photo.

?? Why cool

LATEST IDEAS on NATURE of SUNSPOTSIntroduction

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

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

NEW THEORY - Weiss et al (2004)

Scharmer et al (2004)

New Swedish Solar Telescope on La Palma (Canaries)

Stunning Image(Swedish

telescope, La Palma)

Penumbral structure

created by B

Close-up of penumbra -> new surprises:

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

Points moving along lanes; Bright flows in/out;

Strange dark cores