Abundances in the Solar Atmosphere and in the Solar Wind

Tuesday PM and Wednesday AMEnrico Landi (University of Michigan)

Daniel Wolf Savin (Columbia University)

How to collapse 5 hours of talks and discussion into a 15 minute summary

• Cleary that’s not possible.

• I’ve picked some highlights to illustrate the subjects covered.

• Hopefully this will give a flavor of the Session.

• Apologies in advance to the speakers for mangling what they presented in the Session.

Spectroscopic Determination of Solar Atmosphere Abundances (Peter Young)

• Abundances say something about solar physics

First Ionization Potential (eV)FIP

bias

(cor

ona/

phot

osph

ere)

FIP bias measurements in the solar corona show significant variability

• Coronal holes– no FIP bias (reasonably solid result)

• Quiet Sun– FIP bias = 2 to 4– Transition region not consistent with corona

• Active regions– FIP bias seems to vary with age of structures– Different structures in same AR have different biases

• Interpreting these results is hindered by a lack of quantitative theoretical models.

Solar Wind Heavy Ions Over Solar Cycle 23: ACE/SWICS Measurements (Sue Lepri)

• How much do distribution and fractional contribution from each type of wind changes over solar cycle?

• Goal is to study the solar cycle evolution of both the fast and slow solar wind using ecliptic plane in-situ data.

• How do plasma parameters, charge state distributions and elemental composition evolve with solar cycle?

• Do the fast and slow wind properties evolve in the same way?

ACE/SWICS elemental composition measurements over solar cycle 23

• Heavy elements depleted towards solar minimum, with slow wind becoming more depleted than fast.

• This is in line with predictions for enhanced Coulomb drag, predicted for lower coronal densities.

• FIP bias preserved in slow wind, ordering changes in fast.

• Abundances behavior suggests reduced proton flux from corona & less efficient acceleration of heavy ions.

• Interpreting these results is hindered by a lack of quantitative theoretical models.

Poster presentations of other in-situ studies

• Polar and equatorial coronal hole winds at solar minima: ACE & Ulysses observations– P81: Liang Zhang

• Correlation of heavy ion dropouts with heliospheric and magnetic structures– P83: Micah Weberg

PLENARY: Elemental Fractionation in the Solar Corona and Wind (Martin Laming)

• FIP Effect due to action of ponderomotive force in chromosphere acting on ions, not neutrals.

• Coronal loop acts as resonant cavity for Alfvén waves.

• Alfvén waves can have either chromospheric or coronal origin.

• Waves originating in loop (generally resonant) imply a positive FIP effect as well as He depletion.

Ponderomotive model does good job of reproducing FIP effect in slow & fast wind.

Variations of Elemental Composition in the Solar Wind and SEPs (Kuen Ko)

Variations of Elemental Composition in the Solar Wind and SEPs (Kuen Ko)

• Abundance variations w/corresponding changes at origin are critical to understand solar wind formation.

• Such studies need accurate 3D global coronal magnetic field data.

• Spectroscopic data needed for wide range of temperatures and of both low and high FIP elements.

• Need also spectroscopic and in-situ data that match in space and in time.

Chromospheric abundances from solar flare gamma-ray spectra (Gerry Share)

Simulation of S-Web Corridor Dynamics: Implications for Solar Wind (Aleida Young)

• What is the S-Web theory for slow solar wind?

• Why is it critical for interpreting solar wind observations?

• Current efforts to model S-web corridors.

• See P083 for more details.

SOHO CELIAS MTOF (James Weygand)

DefinitiveResultsUncovering the TrueHeliosphericEnvironment Rounding theSun

The DRUTHERS Mission

The DRUTHERS MissionThe Kamikaze Mission