CAWSES December 10, 2005 1

CMEs

H.S. Hudson

Space Sciences Lab, UC Berkeley

CAWSES December 10, 2005 2

Organization of talk

• Definitions

• Resources

• Properties (key observations; five items)

• Data analysis and interpretations (two items)

• Conclusions

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What is the solar corona?

• Low-beta plasma in a concentric cavity• Slowly-varying lower boundary condition

imposing vertical currents• Body currents (and current sheets) in an

electrically isopotential volume• Massive solar wind forming a lumpy upper

boundary• Flaring (flares and CMEs)

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What is the solar corona?

• Low-beta plasma in a concentric cavity• Slowly-varying lower boundary condition

imposing vertical currents• Body currents (and current sheets) in an

electrically isopotential volume• Massive solar wind forming a lumpy upper

boundary• Flaring (flares and CMEs)

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G. A. Gary, Solar Phys. 203, 71 (2001)

(vA ~ 200 -1/2 km/s at coronal temperatures)

CH

Distribution of coronal plasma

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Definitions

• Flare: a chromospheric transient observed in H

• CME: a coronal transient observed in a white-light coronagraph

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Definitions

• Flare: a coronal transient observed in soft X-rays

• CME: a coronal transient observed in a white-light coronagraph

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Definitions

• Flare: a coronal transient observed in soft X-rays

• CME: a coronal transient observed in a white-light coronagraph

• ICME: a flare/CME product observed in interplanetary space

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CME Resources

• The CUA LASCO catalog

• Other coronagraphs (Mauna Loa, El Leoncito)

• Many non-coronagraphic databases (e.g., Nobeyama)

• My cartoon archive

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Typical catalog entries - July 5, 2005

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Morphology

• Three-part events (front, cavity, core)

• Halo

• Jet-like

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Ways to infer the presence of ICMEs

Hudson & Cliver, JGR 26, 25,199 (2001)

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In-situ Observations of ICMEs

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CME Properties I

• Masses to ~1016 g

• Angular extent ~60o

• Projected velocities to ~3000 km/s

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CME Properties II

• Solar-cycle modulation

• Strong association with flares and eruptive prominences

• Occurrence distribution function differing from that of flares - ?

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Interesting recent observations

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Movie of dimming (Aug 28, 1992)

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(1) Coronal Dimming

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1600A

171AShrinkage, dimming, destruction, oscillation

Helix, ribbons (separatrices?)

TRACE

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Zhang et al., 2001

Timing

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Field changes are now observed with essentially every X-class flare, and they match the flare ribbon locations

Survey of 15 flares by Sudol & Harvey (2004)

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“Isomagnetobars”Before

After

Cartoon from Hudson & Cliver, 2000

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SUMMARY

• There have been many new solar flare/CME results in the past (current?) maximum

• Wonderful databases now exist and are being studied

• Another new wave of solar spacecraft is coming: Solar-B, STEREO, SDO. Alas, no HXR; double alas, no X-ray spectroscopy

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End

http://sprg.ssl.berkeley.edu/~tohban/nuggetshttp://solarmuri.ssl.berkeley.edu/~hudson/cartoons