High Resolution Observations From the Ground
What the SST can do to enhance SOLAR-B science
Göran Scharmer

17th SOT meeting, Tokyo 18 April 2006

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
1
High Resolution Observations From the Ground/ 23

Outline

1

The Swedish 1-m Solar Telescope and its instrumentation

2

Magnetic substructure at 0".1-0".2

3Concluding remarks

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
2
High Resolution Observations From the Ground/ 23

The Swedish 1-m Solar Telescope – SSTFirst light in May 2002
1 m aperture
Integrated adaptive optics
Small number of optical surfaces
Very high optical quality
Most highly resolving solar
telescope ever built⇒ Solar images at ∼ 0.00 1 resolution

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
3High Resolution Observations From the Ground/ 23

The SST – Schematic drawing
Transmitting telescope
optics made of fusedsilica for stable
polarization properties.
Field mirror can betilted for compensationof atmosphericdispersion.
A. Field mirror and fieldlens
B. Schupmann corrector
C. Tip-tilt mirror, adaptive
mirror, re-imaging lens
Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
4High Resolution Observations From the Ground/ 23

Instrumentation and techniques

Adaptive Optics
Phase-diversity and
MOMFBD imaging andrestauration
Spectrograph (3 exitports)
Spectro-polarimeter(first light April 2006)
Dual Fabry–Pérot filter
system & Imaging
polarimeter (end of2006)

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
5High Resolution Observations From the Ground/ 23

SST imaging polarimeter (operational early 2007)

Dual Fabry-Perot filter: High-resolution & high-reflectivity etaloncombined with low-resolution & low-reflectivity etalon (Scharmer2006).
FOV 70"x70", 0".07/pixel
Wavelength range 520-860 nm, FWHM 60 mA at 630 nm
High transmission (FPI > 80%, pre-filters 70-80%)
Polarizing beam splitter with two 1kx1k CCD’s
Third CCD recording through pre-filter to allow image restauration
Liquid crystals and filter tuned while reading out CCD’s (10 ms)
Back illuminated, low-noise CCD’s operating at 30 Hz frame rate

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
6High Resolution Observations From the Ground/ 23

SST polarization model (Selbing 2005)

SST strongly polarizing, polarization measurements useless without
good polarization model.
Fused silica in all transmitting telescope optics ⇒ stable
polarization properties
The same polarization model used for polarimetry based on
narrow-band filters and on the spectrograph
Uses 5-component general Müller matrix for 1-meter lensModel based on data with 1-meter rotating linear polarizer
Model verified with unpolarized input light

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
7High Resolution Observations From the Ground/ 23Polarization model verification, I ⇒ Q cross-talk

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
8High Resolution Observations From the Ground/ 23

Polarization model verification, I ⇒ U cross-talk

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
9High Resolution Observations From the Ground/ 23

Polarization model verification, I ⇒ V cross-talk

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
10High Resolution Observations From the Ground/ 23

Sunspot fine structure close to the resolution limit(Scharmer et al. 2002)

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
11High Resolution Observations From the Ground/ 23

Magnetic substructure close to the resolution limit(Berger et al. 2005)

arcseconds

5a0b

a: Wideband
b: Magnetogram
c: Doppler
d: G-bandarcseconds

5c

00d
5
arcseconds
Göran Scharmer (ISP)05arcseconds

17th SOT meeting, Tokyo 18 April 2006
12
High Resolution Observations From the Ground/ 23

3D structures in sunspots and pores (Lites et al. 2004)

25 July 2002
Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
13High Resolution Observations From the Ground/ 23

3D light bridge structure (Lites et al. 2004)

25 July 2002

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 200614
High Resolution Observations From the Ground/ 23

Dark-cored penumbra filaments (Spruit & Scharmer
2006)

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 200615
High Resolution Observations From the Ground/ 23

Connection light bridges - dark cored filaments(Löfdahl et al. in prep.)

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 200616
High Resolution Observations From the Ground/ 23

Magnetogram (suggests spine structure rather thanembedded flux tubes)

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 200617
High Resolution Observations From the Ground/ 23

First Stokes images from SST (individually scaled)Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
18
High Resolution Observations From the Ground/ 23

Proposed penumbra magnetic field (Spruit & Scharmer 2006)

Note: Any two-component representation would need gradients inboth components!

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
19
High Resolution Observations From the Ground/ 23

SST observing time 2005-2006

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 200620
High Resolution Observations From the Ground/ 23

SST data of potential importance to SOLAR-B

For up to ≈ 1 − 2 hours on ≈ 10% of the days, SST can provide datastrongly enhanced by image restauration and short exposures:
Highly resolved (≈ 0”.1) images and movies in Ca H wing and atblue wavelengths
Highly resolved (≈ 0”.2) multi-wavelength Stokes images using
dual FPI system (operational early 2007). Low residual seeing
induced cross-talk.
Spectropolarimetric data will be available but unlikely to becomparable with SOLAR-B data as regards spatial resolution due tolong integration times needed.

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
21
High Resolution Observations From the Ground/ 23

Operational constraints

SST used by several partners (Oslo and Utrecht Universities, IAC,
Max-Planck Institut für Sonnensystemforschung, LMSAL) andprograms (Opticon, IAC ITP). Collaborations require contacts
with individual institutes
IAC International Time Program (ITP) program provides directmeans of obtaining SST observing time
Swedish financial support for operating SST is declining

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 200622
High Resolution Observations From the Ground/ 23

Comments on interpretation

Data at 0".1 spatial resolution suggest that:τ = 1 surface strongly warped by magnetic field, needs
sophistication of diagnostics and inversion techniques
No evidence for embedded flux tubes in outer penumbra.
Connection dark-cored penumbral filaments and light bridge darklanes suggest field-free gaps in penumbra (Spruit & Scharmer2006).
Inversion techniques unlikely to resolve multiple components withcomplex magnetic field topologies. Supplementary measurements
at high spatial resolution desirable in order to help resolving
ambiguities in interpretation.

Göran Scharmer (ISP)

17th SOT meeting, Tokyo 18 April 2006
23
High Resolution Observations From the Ground/ 23