Space, Astro, etc. ‐‐‐ what’s the
difference? • Space Physics:
– Heliosphere: Earth’s magnetosphere, solar wind – Direct in‐situ inves'ga'on by spacecraN
• Astronomy and Astrophysics: – Universe beyond the Solar System – Remote observa'ons only (telescopes)
• Solar Physics: – Solar corona, solar dynamo – Not‐so remote observa'ons…
Space, Astro, etc. ‐‐‐ what’s the
difference? • Space Physics:
– American Geophysical Union (AGU) Mee'ngs – Journal Geophys. Res. (JGR); Geophys. Res. LeY.(GRL)
• Astronomy and Astrophysics: – American Astronomical Society (AAS) Mee'ngs – Astrophys. Journal (ApJ); Mon. Not. Roy. Ast. Soc. (MNRAS)
• Solar Physics: – Solar Physics Div. (SPD) of AAS ‐‐‐ rota'ng mee'ngs – Solar Physics, ApJ
Major Puzzles in Solar Physics
• Solar Interior: – Differen'al Rota'on – Solar dynamo and the 22‐year sunspot cycle
• Solar Corona: – Coronal Hea'ng – Solar Flares – Coronal Mass Ejec'ons (CMEs)
Solar MHD Dynamo
• Origin of Sun’s magne'c field (E. Parker 1950s) • Large‐scale magne'c field reverses every 11 years
Solar Flares and Magne'c Reconnec'on
• Solar Flares are powered by Magne3c Reconnec3on ‐‐‐ sudden rapid rearrangement of magne'c field accompanied by a release (dissipa'on) of magne'c energy.
Solar Wind • Predicted by Gene Parker in 1958
• Plasma streaming outward from Sun
• Natural laboratory for MHD turbulence
• Wind hea'ng poorly understood
Consequences of Magnetospheric Reconnec'on
• Magne'c substorms • Satellite and power grid disruptuons
• Aurora Borealis
Astrophysical Plasmas
• ONen Collisionless: – non‐Maxwellian distribu'on func'ons – Power‐law tails ‐‐‐ energe'c par'cles
(including rela'vis'c ‐‐‐ cosmic rays)
• ONen turbulent • Radia've processes oNen important
Interstellar Medium (ISM) • Magne'zed • Turbulent • Filled with Cosmic Rays • Permeated by starlight and CMB n kBT ~ B2/2μ0 ~ ρv2 ~ PCR ~ Ucmb ~ Urad
• Inhomogeneous: – cold dense molecular clouds (30K) – warm atomic neutral and ionized gas (104 K) – hot ionized “coronal” plasma (106 K)
Supernova Explosions
• S'r interstellar turbulence • Accelerate cosmic rays • Enrich ISM with heavy elements
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