Interesting Facts about Our Sun

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Slide 1

General Properties

Absolute visual magnitude MV = 4.83

Central temperature = 15 million 0K

X = 0.73, Y = 0.25, Z = 0.02

Initial abundances:

Age: ~ 4.52 Gyr

Spectral type G2V

Effective (surface) temperature = 5770 0K

0

Absolute bolometric magnitude Mbol = 4.76

The Sun

Slide 2

The Sun’s Interior Structure

Temp, density and pressure decr. outward

Energy generation via nuclear fusion

Energy transport via radiation

Energy transport via convection

Flow of energy

Photosphere

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Slide 3

Interior Structure of the Sun

Site of main energy production

dL/dr

r/R0

0.5

0.4

0.3

0.2

0.1

0

Slide 4

Interior Structure of the Sun

Mass composition

Mass fraction

r/R0

0.5

0.4

0.3

0.2

0.1

0.6

0.1

0.6

0.8

0.7

0.5

0.4

0.3

0.2

11H

42He

32He (x100)

0

Slide 5

The Sun’s Atmosphere

Only visible during solar eclipses

Apparent surface of the sun

Heat Flow

Solar interior

Temp. incr. inward

0

Slide 6

Granulation

… is the visible consequence of convection

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Slide 7

Sun Spots (I)

0

Slide 8

Sun Spots (II)

Visible

Ultraviolet

Cooler regions of the photosphere (T ≈ 4000 K).

Active Regions

0

Slide 9

Solar Activity, seen in soft X-rays

0

Slide 10

Magnetic Fields in Sun Spots

Magnetic fields on the photosphere can be measured through the Zeeman effect

→ Sun Spots are related to magnetic activity on the photosphere

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Slide 11

Sun Spots (III)

Related to magnetic activity.

Magnetic field in sun spots is about 1000 times stronger than average.

In sun spots, magnetic field lines emerge out of the photosphere.

Magnetic North Poles

Magnetic South Poles

0

Slide 12

Magnetic Loops