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Sixth Solar-B Science Meeting

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Simulations taking on a new degree of realism. Beginnings of confrontation of ... Magneto-convection (both strong and weak field cases): detailed comparison of ... – PowerPoint PPT presentation

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Title: Sixth Solar-B Science Meeting


1
Sixth Solar-B Science Meeting
  • Summary Review Science With the SOT

2
6th Solar-B Science Meeting Theme Qualitative
Advances in Numerical Modeling and Simulations
  • Simulations taking on a new degree of realism
  • Beginnings of confrontation of models and
    observations
  • Personal Highlights from the lower atmosphere
    observed by SOT
  • Magneto-convection (both strong and weak field
    cases) detailed comparison of plage simulations
    and observations (Stein review)
  • Flux emergence (review by Moreno Insertis,
    several other papers and posters)
  • Photospheric, chromospheric reconnection (review
    by Chae, poster by Magara)
  • A common thread moving toward realistic 3-D MHD
    models

3
  • The Solar-B Optical Telescope a breakthrough in
    the combination of temporal coverage, angular
    resolution, polarimetry
  • Will enable
  • First continuous coverage of vector magnetic
    field, photospheric and chromospheric dynamics on
    a scale that begins to resolve solar structures
  • Highest resolution vector field measurements
    (even with A/O, ground-based measurements will
    probably fall short)
  • But
  • SOT must interact closely with other data sources
    to address most of the primary science goals!

4
FACT Solar-B angular resolution is already well
below the state-of-the-art of modern ground-based
observations using A/O and post-observation image
processing! FACT Other, newer spectroscopic/polar
imetric diagnostics will be needed to supplement
Solar-B SOT observations to solve the primary
scientific questions! A few examples
5
Photospheric structure at 0.1 from the SST
(Facular brightness structure at the limb a
recent verification of MHD simulations based on
new observations)
6
Chromospheric Dynamics seen in Ha at 0.15
resolution
(This is quite possibly the single most valuable
observation of the chromosphere ever)
7
  • 3-D vector magnetic field measurements from
    photosphere into the chromosphere
  • Stokes Measurements of CaII IRT
  • Stokes profiles of surrounding photospheric lines
  • Complete self-consistent inversion of all line
    profiles to get height dependence of B
  • Derive vector currents in the volume!

(Measurements from SPINOR polarimeter,
Socas-Navarro 2005, in press)
8
Vector Magnetic maps of prominences derived from
He I
May 25, 2002. Sacramento Peak Observatory Dunn
Solar Telescope with the Advanced Stokes
Polarimeter Casini et al. 2003, ApJ 598, L67
  • Principal Component Analysis (PCA)
  • Inference of the vector magnetic field
  • Inference of the thermo-dynamic properties
  • Use complete description of the atomic physics of
    scattering polarization (Hanle/Kemp/Zeeman)

9
Message Solar-B community needs to start now to
integrate observations not only from other
spacecraft, but also from ground-based
observatories into the science planning. Solar-B
has the luxury of a long useful lifetime. This
is necessary in order to profit from the very
occasional times that extremely high resolution
is attainable from the ground.
10
  • Many exciting science prospects presented at this
    meeting, but
  • Too many to give justice to in 15 minutes, so
  • I will put forth some inflammatory statements!
  • I expect these to incite heated discussion and
    rebuttals!

11
Inflammatory 1 Most all observational studies
of magnetic helicity from vector field
observations so far have not demonstrated that
they are reliable.
Main Objection They are based on vector magnetic
field observations that contain serious errors
errors that are magnified in the solution because
spatial derivatives of the observed fields
(currents) are required.
  • Helicity injection calculations (i.e. Kusano et
    al. method) do not suffer from several limiting
    assumptions concerning direct calculations of
    helicity, but still depend on time and spatial
    derivatives of the observed magnetic field vector.

12
Solar-B will fix this! (for active regions)
Highly quantitative measures of the field vector
on spatial scales that resolve or nearly resolve
the field structure on the photosphere will
provide the actual fields that enter e.g. the
induction equation! Solar-B data will allow us to
estimate the range of validity of these
calculations through derived error estimates of
the field and measured velocities.
13
Inflammatory 2 A possible source of
chromospheric and coronal heating of the quiet
Sun has been largely ignored
  • Weak, mixed polarity internetwork flux, advected
    to the supergranular boundaries, must undergo
    forced reconnection there
  • Only the most sensitive polarimeters are able to
    detect the weak IN flux (almost completely missed
    by MDI)
  • Total unsigned flux of IN fields network flux
  • Mixture of field strengths (up to kilogauss)
    Strong fields in intergranular lanes, weaker
    fields over granules

Note a statement by Alan Title during discussion
after his review Local reconnection of field
lines in the lower atmosphere is a major effect.
14
  • Solar-B Observations
  • Greatly improve spatial resolution of IN flux at
    high resolution
  • Help to constrain the properties of the weak IN
    flux, especially the intrinsic field strength
  • Record evolution of the flux as it is advected to
    network elements
  • Record the consequences of this cancellation
    above the photosphere
  • Need coordinated IR Spectropolarimetry at high
    resolution from ground-based instruments!

15
Inflammatory 3 Wholesale flux retraction of
fields already emerged into the chromosphere and
above is a myth
  • Field curvature must be smaller than the local
    scale height if magnetic tension forces are to
    retract the field
  • Reconnection must occur at or very close to the
    photosphere for flux to appear to cancel there
  • Fields already emerged and expanded into the
    chromosphere and corona will be extremely
    difficult to retract
  • Possibility of U-loop emergence and eventual
    cancellation is now being recognized

16
A very early result from Yohkoh corona is ever
expanding outward.
17
3. AR magnetic flux losses (Martinez Pillet 2005,
in preparation)
  • But, what happened to the magentic flux?
  • Linear flux decay (69 !)
  • Reaches a plateau
  • Coronal events localized right before the
    plateau

SOHO/MDI
18
  • U-Loops and Prominences
  • Schmieder presentation evidence for U-loops at
    filament footpoints
  • Wang proper motions in d-sunspot regions
    opposite polarities converging

Flux ejection, and accompanying helicity
ejection, may well be a fundamental process of
the solar cycle. Solar-B observations will define
the frequency and importance of this process
(U-loops). This will probably require
reconnection at the photospheric level on very
small scales in downflow regions.
19
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20
Concave (U-loop) vector field topology at
polarity inversion line under low-lying active
region filament.
21
  • Concluding Statements
  • Solar-B SOT observations will define the nature
    of the active region magnetic field and its
    evolution
  • Solar-B must integrate observing programs with
    other sources, especially ground-based high
    resolution observations
  • From an observers point of view, MHD models are
    now coming of age
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