N. A. SchwadronU. New Hampshire

Solar Wind and Coronal Electron Temperature in

the Protracted Solar Minimum, the Cycle 24

Mini Maximum, and Over Centuries

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2 Apr 17, 2014Schwadron - NESSC

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Background - Ulysses

McComas et al., ApJ, 2013

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Protracted Min (23) and Mini Max (24)

• Dropping solar wind• Flux• Pressure• Magnetic Field

• Continues trend observed by Ulysses

McComas et al., ApJ, 2013

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Energy-per-particle fixed from the Source

Schwadron et al., 2008

Pevtsov et al., 2003

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Correlated Reduction in Ram Pressure and Magnetic FLux

McComas et al., ApJ, 2013

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Reductions in Magnetic Field & SSN

• SSN (black)• Predicted (red)• OMNI (blue)• 10Be (green)• Magnetic Flux Balance

(Schwadron et al.,, 2010)

Goelzer et al., ApJ, 2013

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Alfven Radius in the Mini Maximum

Goelzer et al., JGR, 2014

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Significantly worsening space environment in Cycle 24

Schwadron et al., 2014

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B. U. Colloquium, Feb 2008

Paths of deposited Energy

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• Solar Wind Scaling Law

• Electron heat conduction and radiative losses

Fast windCool, Dark

Slow windWarm,Brighter

Radiative LossHot, Bright

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Scaling Law Model - THEN

Only free parameter is expansion factor= 6.2 taken here

Similar to 5.8 expansion factor found by Munro & Jackson [1977]

Maps to 8-12 G fields

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Scaling Law Model - NOW

Not Observed rise in coronal temperature in cycle 24

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Cycle 24 Decay in Coronal Temp

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Historic Period – Dalton-like

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Conclusions

Protracted Cycle 23 and Mini Max of 24 historic periods of low activity

Affect acting across all/most elements of system

Further more stringent test of coronal scaling law

Weak effect on Alfven radiusWorsening Radiation Environment

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