Solar and Heliospheric Physics CSI 769 ASTR 769

Solar and Heliospheric Physics CSI 769 / ASTR 769 Spring 2008 Jie Zhang

What Physics? • Plasma Physics • MHD (Magnetohydrodynamics) Physics • Magnetism • Magnetic Reconnection • Particle Acceleration

The Cosmological Context We are located in the middle of the Milky Way Galaxy 28, 000 light years from the center One of 200 billion stars in our Galaxy

The Sun: an Ordinary Star • An ordinary main sequence star • 5 billion years old • 5 billion years more to go

Local Interstellar space Solar wind creates a big teardropshaped heliosphere around the solar system, by interacting with the interstellar wind

Local Interplanetary Space The Earth 3 rd planet from the Sun 1 AU = 150 million km Travel time: By light -8 minutes By Solar Wind- ~ 100 hrs

What Practical Usage? "Space weather describes the conditions in space that affect Earth and its technological systems. Our space weather is a consequence of the behavior of the sun, the nature of Earth's magnetic field, and our location in the solar system” ----National Academy of Science, 1997

Space Weather: the Process It starts from an eruption from the Sun. Prediction depends on how it propagates

Space Weather: effects Aurora; Geomagnetic Storm From Space

Space Weather: effects An adverse effect Power failure due to March 1989 storm Damaged transformer

Space Weather: effects On Human Space Exploration On crew and passengers of polar-route airplanes

Space Weather: effects On Satellite Operation

Space Weather: effects On Communication and Navigation

Space Weather: the Systems

The Source of the Energy? Planet Magnetic energy through magnetic field generated by solar dynamo, which has 11 -year solar cycle Solar Cycle

Storage of Energy? Planet Energy stored and released in magnetic field

Release of Energy and the driver? Planet Coronal mass ejections

Heliosphere: solar wind Planet Spiral solar wind magnetic field: radial motion of solar wind combined with Sun’s rotation Sprinkler Analogy

Magnetosphere Planet A cometshaped region around the Earth

Magnetosphere Planet Electric Currents in Magnetosphere

Magnetosphere Planet Energetic particles in Van Allen radiation belt

Ionosphere Planet Density fluctuation affects radio wave reflection and transmission

Neutral Upper Atmosphere Planet It is coupled with ionosphere

Re-focus on Physics • Energy Storage: magnetism • Energy Release: magnetic reconnection • Energy Transportation

The End