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SUN COURSE - SLIDE SHOW 1
For Centuries We Have Worshipped the Sun
E.g., Greece -- Sun God: "Helios"
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…
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
James Gregory
Appointed
Lined
up of
telescope
1stUniversity
regius along
profLibrary
maths
north-south
in St
Aline.
1668
Given Upper
Hall
as
place
of work
Elected
1668
30)
(recommendation
Early FRS
pendulum
of(age
clock
Newton)
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
??Age
R == 10;
y;1000
?1000
Chemical
100;
1,000,000 y;
composition
RE
1,000,000,000y
Radius
91%
Age -H, 700
Mmbillion
(1Mm
4.6
8.9%
He,
= minor
1000 km)
years
+
= 100
x
(1b
elements
= 1000
Earth
million)
(O,
C, N, Fe
...)
Ball of gas held together by gravity
? Mean distance from Earth 93 million miles = 215 Ro
1. Overall Structure
Interior --> Core,
Convection zone
Atmosphere -->
Photosphere,
Chromosphere, Corona
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")
2. Photosphere
Temperature = 6000 K
Close-up :
Sunspots -- in pairs
Covered
with
(why ?)
turbulent convection
cellsRotates
-- "Granulation"
-- not like
solid ball -- Equator 26
Same
as
porridge
or
days -- Poles 37 days
mackerel sky
Photosphere
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Covered with
turbulent
convection cells:
“Granulation”
(1 Mm)
“Supergranulation”
(15 Mm)
Amazing
images at
from
La Palma
this year
In closeup:
points,
flowers,
ribbons
(created by
magnetic
fields)
3. SUNS
POTS
Sunspots
Existence known since 350 BC (Greece), 28 BC (China)
In West, no ref until
850 AD;
Galileo (1611)
Umbra
Penumbra
Site strong B.
Flux tube - ?? Model
Dark because Cool
1600K cooler
than photo.
?? Why cool
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
Penumbra (40 Mm, B intermed, inclined) radial light/d
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 a
YUV420 codec decompressor
are needed to see this picture.
Points moving along lanes; Bright flows in/out;
Strange dark cores