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Understanding Solar Flares and Coronal Mass Ejections: Impact on Earth and Beyond

This presentation explores the fascinating phenomena of solar flares and coronal mass ejections (CMEs) from the Sun. We’ll discuss how these powerful eruptions influence space weather, impacting satellite communications and creating stunning auroras on Earth. Learn about the Sunspot cycle, the role of the Earth's magnetic field in shielding us from these solar events, and the science behind auroras. We also cover significant historical events like the October 2003 mega-flare and the advancements of space observatories like SOHO and STEREO.

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Understanding Solar Flares and Coronal Mass Ejections: Impact on Earth and Beyond

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Presentation Transcript

  1. SUN COURSE - SLIDE SHOW 8 Today: Solar flares & coronal mass ejections (CME’s)

  2. 1. Introduction - Sunspot Numbers

  3. Corona Changes with Solar Cycle

  4. Coronal Mass Ejections (see talk 3) SOHO Coronagraph -- Artificial eclipse Discovered huge ejections of plasma Can reach Earth - communications / satellites

  5. Northern Lights(Aurora)

  6. The Magnetic Field of the Earth • The Earth’s magnetic field is like that of a bar magnet close to the Earth • The solar wind distorts the magnetic field into a comet like shape on the nightside (the magnetotail).

  7. Indirect effects of CME impact Astronaut safety: Enhanced radiation levels Telecommunication and power lines

  8. What causes the aurora ? Distortion of Earth’s magnetic field by CME energizes particles in the magnetotail. These particles hit the molecules of the upper atmosphere and make them glow Different colours: different molecules (oxygen, nitrogen), also the level of excitation of the molecules

  9. What accelerates the particles ? Reconnection in the tail Energetic particles move along the magnetic field, and hit the atmosphere close to the north and south poles ! The Earth’s magnetic field shields us from any direct effects of CME’s !

  10. Aurora pictures taken from the Space Shuttle Height of auroral emission: 100-400 km (60 - 200 miles) Space shuttle orbit has similar height, so the Space shuttle can go directly through the aurora !

  11. 3. On October 28, 2003 Photo sphere from SOHO

  12. Magnetic field from SOHO

  13. X-ray Intensity(t) -3rdlargest

  14. Outer Coronafrom SOHO CME 2000 km/s (5 times faster than normal) Snow -- relc particles

  15. 1 Week Later - Fireworks Continued SOHO Site (Nov 6): Just as solar scientists were ready to start breathing normally again, active region 10486 blasted off yet another mega-flare. This one saturated the X-ray detectors on the NOAA's GOES satellites; the jury was therefore out for a while on the definitive classification of the flare -- speculations ranged from simply well above X20, to X40 or even X50. Today word came from the SEC that their best estimate was X28. It is now official: We have a new number 1 X-ray flare for the record books.

  16. The biggest solar flare ever recorded ! X-ray intensity(t)

  17. Close-up of plasma motions Conjuring trick -- plasma appearing by magic ?

  18. Solar Flare • Very sudden brightening in corona • -- due to appearance of heat • Occurs above complex sunspots • The only possible source of vast amount of energy - B • Heating is ohmic ( ) • How do large currents appear ?? • How is magnetic energy converted into heat (reconnection) ?

  19. 4. Overall Picture of Solar Flare In core - magnetic tube twisted (energy stored in fff) - erupts (catastrophe) - drives reconnection

  20. Reconnection heats loops/ribbons

  21. Reconnection heats loops/ribbons Chromosphere Reconnection proceeds -- loops rise

  22. Reconn. Accelerate p’cles --> hard X

  23. (Priest and Schrijver 1999) Reconnection heats loops Continues:new loops form & evaporate. Old loops cool & drain Feet move apart

  24. Ex of Loops Rising

  25. Same process for eruptions outside a.r. Ex of rising cusp

  26. Before: twisted, force-free --> energy stored

  27. Example from SOHO

  28. TRACE - 1st image of j sheet

  29. RHESSI Overlay of TRACE Reconnection accelerates particles --> hard X • Red contours: X-rays from high energy pcls • Blue contours: X-rays from very high energy particles

  30. Effects: (i) creates wave

  31. (ii) Wave --Movie from TRACE

  32. Cause of Eruption ? Magnetic Catastrophe 2.5 D Model

  33. Numerical Model Suggestive of Catastrophe

  34. Cause of energy release -- reconnection When an X-point collapses

  35. Reconnection converts energy

  36. Future Space Observatories STEREO (NASA) * Two satellites * Stereoscopic images of corona Solar Orbiter (ESA) * 3 times closer than Mercury Solar Dynamics Observatory Successor to SOHO (super - MDI + Trace)

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