Universal Heliophysical ProcessesGeorge Siscoe

Boston University

● 50 years exploring has led to a watershed betweenexploration and consolidation

adolescence and maturityspace physics and heliophysics

● What heliophysics is notspace physics renamed

an historical science like geology, planetology, biology a derivative science

● A derivative science needs only the laws of physicsIt has no regularities peculiar to itIt has no synthesizing laws of its own It has no inherent principles with explanatory power

sufficient to link its own distinctive phenomena

In short, it has no paradigms

What Heliophysics Is

● Heliophysics is an environmental science:a unique hybrid between meteorology and astrophysics

● It has an applied branch: space weather started 1990s (NSWP)

● It has a pure branch: universal processes started 2007 (IHY)

● It is a discipline that comprisesa body of data and a set of paradigms (i.e., general laws—perhaps mostly still undiscovered) specific to magnetized plasmas and neutrals in the heliosphere interacting with themselves and with gravitating bodies and their atmospheres

● This conference concerns the general laws of heliophysics and programs to uncover them

Examples of Discipline-Specific General Laws or Principles

● ASTRONOMYKepler’s Laws, Hertzsprung-Russell diagram, expanding universe

● CHEMISTRYperiodic table, valence, Le Chatelier’s Principle

● BIOLOGY evolution, double helix

● GEOLOGY deep time, plate tectonics

● METEOROLOGY Hadley cell, baroclinic instability

● HELIOPHYSICS (place-holding examples)solar (stellar) windmagnetospheric convection magnetic organization of matterexplosive energy conversion (CMEs & substorms)magnetically coupled systems

Organization of the Universeby Long-Range Forces

Heliophysics

PlasmaAstrophysics

Astro

Solar

GravitationalOrganization

Solar System&

Planetology

AstronomyAstrophysics

MagneticOrganization

ContractionAngular Momentum

GalaxiesStars

Solar systemsPlanets

SatellitesPlanetary systems

Rings

CreationExpansion

AnnihilationSheets (HCS)

Tubes (Sunspots)Cells (magnetospheres)

g = -4 Gρxg = 0

Gravity hasmaterial sources

B = 0xB = μoJ

Magnetism has dynamo sources

Gravitational + Magnetic OrganizationSolar and Stellar WindsCMEs and Substorms

Cosmic raysPlanetary Ionospheres

“It cannot be emphasized too strongly that … understanding of the magnetic activity… in the astronomical universe, can be achieved only by coordinated study of the various forms of activity that are accessible to quantitative observation in the solar system.” E. Parker Cosmical Magnetic Fields

2004

Richness of heliospheric examples

Universal Heliophysical Processes

Electron cyclotron frequency waves upstream of bow shocks of planets as function of the solar wind field strength

Radiometric scaling law for low-frequency planetary magnetospheric radio emissions

Universal slope to suprathermal tail of ion distribution function

Universal dependence of heating on magnetic flux

10-13

10-11

10-9

10-7

10-5

10-3

10-1

101

103

1 10 100

tail retail 5:23:15 PM 2/7/06

*FWtail*tail+SWSW distribution1FWFW<FW>meanFWnetFWbkgsum core+tail quietFWPI upFW -26day to TS LECPFW -20day to TS LECPFW -26day to TS LECPFW -20day to TS LECPFW(Vr broadened)Tail with cutoffFW ionsFW H+f bg=(min+mean)/2

Pha

se S

pace

Den

sity

(s

3 /km

6 )

W Ion Speed/Solar Wind Speed

f(w) = fow -5

(in solar wind frame)

H+

<R> = 4.86 AU

ULEIS

1 AU

4.23 AU

94 AU

Core pickup protons

46 AUSolar Windthermal tail

Desch and Kaiser, 1984Russell and Hoppe, 1983Fisk and Gloeckler, 2006

X ray bright points

Solar active regions

G,K & M dwarfs

T Tauri stars

Convective envelope

Pevtsov et al., 2003

Heliospheric Examples of Cosmical Magnetic Forms

• Sheets (current sheets):Heliospheric current sheet (HCS)Planetary current sheetsAuroral curtains

• Tubes (flux ropes):Coronal Mass Ejections (CMEs)CMEs, HCS, and “blobs”Solar wind flux tube spaghettiFlux transfer events (FTEs)

• CellsICMEsMagnetospheresHeliospheres

Lin et al., 2005

Crooker et al., 1993

Borovsky, 2007

Russell and Elphic, 1979

Bagenal, 2008

Explosive Energy ConversionA universal process illustrated by

CME Initiation and PropagationThe issue: Is initiation a result of a microscale

instability causing a sudden burst of magnetic reconnection or a macroscale mechanical instability?

Macroscale option: Pneuman, The 'melon-seed' mechanism and coronal transients (1984)

And since then:

Mikic and Linker

Forbes, 2008

Time = 2:14 Time = 2:22 Time = 2:24

Triggered Substorm Using OpenGGCM at CCMC

Is there a universal initiation process?Diagnostic test:

Does rapid reconnection precede motion or vice versa?

Vice versa

• Rate determined by microstructure of reconnection

• Plus macroscale geometry of reconnection (consensus view)?

• Or rate determined by macro-kinetics (Axford conjecture)?

Pritchett and Coroniti, 2004

What determines rate of global reconnection?

Fuselier et al., 2007-1

-0.5

0

0.5

1

1.5

72200 72400 72600 72800 73000 73200 73400

DMSP data-model comparisona1398344.195

vDMSPRidleyRaederWeimer

time

GEM Metrics ChallengeHesse 2001

• New idea: global rate of reconnection set by minimizing rate of entropy generation between bow shock and reconnection dissipation

• Reconnection decreases the rate of entropy generation at the bow shock (?) but increases it at the reconnection site

• If the curves of decrease and increase as a function of reconnection rate cross, the rate is the value at the point of crossing

Need to move from a reductionist (microphysics) approach to a systems (macrophysics) approach

IMF = 0

IMF = -20Southward IMF

Reconnection Current SystemMagnetopause SegmentMagnetosheath Segment

Bow-Shock Segment

x

z

-y

Summary• Heliophysics is an environmental science, a unique hybrid

between meteorology and astrophysics• It comprises a body of data and a set of paradigms (general

laws—perhaps mostly still undiscovered) specific to magnetized plasmas and neutrals in the heliosphere interacting with themselves and with gravitating bodies and their atmospheres

• Magnetic organization of matter induces spatial and temporal structures on all scales (the Parker principle)

• Empirical laws (Kepler-like) reveal the presence of universal laws (Newton-like) underlying these structures

• Explosive energy conversion exemplified by CMEs and substorms can test the value of a heliophysics-universal-processes project

• Cellular forms of magnetic structure (exemplified by magnetospheres) should be treated as complex, non-locally coupled systems (a new heliophysical paradigm)