The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

• Basic SW energy balance:

Velli

Solar windRadiation

Thermal Conduction

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

• “Slow” Wind: • Where from?

• “Fast” Wind: • How accelerated?

Velli

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

P. Hess (GMU) is attempting to use sun grazing comets to determine wind speed profiles in-situ.

Asymptotic speed reached at ~ 12 Rsun. SPP perihelion is 9 Rs.

Hess

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

• Steady (“Fast”) Wind:– cooler charge states,– photospheric

composition, – lower H/O ratio, – narrow H/O ratio

distribution (less variable)

• coronal hole source regions

• Unsteady (“Slow”) Wind:– hotter charge states, – coronal composition, – higher H/O ratio, – broad H/O distribution

(more variable) ratio, – FIP enhanced, – Mass fractionation

• suggests a multitude of source regions (e.g., loops)

Zurbuchen

• Charge state diagnostics: – O6+ dominant in 1MK corona use as a temp marker– O hotter/faster than H in fast wind strong heating

near Sun• Use freeze-in temperatures of different species to

constrain radial temperature profile in the corona. (Enrico Landi, UMichigan).– Freeze-in rate for C* is roughly the same (by order of

magnitude) C* freeze-in at roughly the same location. – C6/C4 tracks the wind velocity.

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

Zurbuchen

Linker

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

Way to supply a highly variable wind from “closed” sourcesLarger width than the plasma sheetAsymmetric about the HCS

Not clear if the (interchange) reconnections associated with the S-Web structure can energize the wind.

High res simulations reveal enormous amount of structure in the magnetic field

Regions of high-Q (separatrices and QSL’s) can be thought of as “seams” in the coronal magnetic field structure at which current sheets are likely to form, and where (interchange) reconnection can occur.

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

Pseudo-Streamer

Streamer Belt

Crooker

Linker

Schwadron & McComas Scaling Law:Anti-correlation of speed and temperature.Proton flux proportional to open magnetic flux in solar wind.

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

Schwadron

• Reduction of open flux leads to reduced O freeze-in temperature, and therefore a reduced power in the solar wind.

The Role of Magnetic Geometry andReconnection in the Origin of the Solar Wind

Schwadron