SUN COURSE - SLIDE SHOW 1. For Centuries We Have Worshipped the Sun E.g., Greece -- Sun God:...
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Transcript of SUN COURSE - SLIDE SHOW 1. For Centuries We Have Worshipped the Sun E.g., Greece -- Sun God:...
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