Week 8 (1): Sun and Solar Wind

Question 1

Name 3 layers of the Sun and state their properties

Answer 1

1) Photosphere: T = 5780 K, peaks at 5000 A
- The radiant layer of the Sun
- Sunspots occur where magnetic field emerges

2) Chromosphere:
- Emits reddish light from strong H-alpha emission at 6563 A
- CS have emission spectrum, while PS have absorption spectrum

3) Corona: T = 10e6 K, Low density
- T high enough to allow solar atmosphere to escape into space, where magnetic field lines are open
- Have trace magnetic field lines
- Visible due to Thompson scattering of light by e

Question 2

Explain how sunspots form

Answer 2

• Sunspots are regions of the Sun’s surface that appears darker than their surrounding, denoting areas where magnetic field lines emerge
• Occurs in +/- pairs joined by magnetic field loop
• Magnetic field on sunspots suppress convection, preventing surrounding plasma from entering the region

Question 3

Define Solar Wind and list the components of a heliosphere. Draw out its diagram

Answer 3

Solar Wind: Continuous flow of positive ions and e

Heliosphere: Cavity carved out in the ISM by solar wind
- Termination shock: A distance from the Sun where solar wind slows down from super to subsonic
- Heliopause: The boundary of solar wind
- Heliosheath: Layer between termination shock and Heliopause
- Bow shock: The expected upstream of Heliopause in the ISM