SOTSP: Hinode-(SST Soup) 1. Wave Transmission in the Quiet Sun 2. Wave Variations in the Penumbral Fine Structure
2007-08-17T11:02:00 to 2007-08-17T11:32:00
Science Goal: Hinode-(SST Soup) 1. Wave Transmission in the Quiet Sun 2. Wave Variations in the Penumbral Fine Structure
Program: Deep Mode, ROI 3, 175 slit positions
Target: MHD wave
xcen=-41 ycen=0
Instrument: SOTSP
HOP/JOP: 26
Description:
Daily Note and User Entry: Weekly Meeting HOP29, filament, prominence, cavities (18 -22 UT). HOP12 (22 - 3 UT, can be extended to 6 UT if no conflict). HOP26 (4 or more hrs, between 11 - 18 UT). XRT: CCD Bakeout plus test X-ray images EIS: 3.5 hours sensitivity monitoring to run in weekend plan (discuss scheduling today)
Request to SOT: 1. 1)
SOT-SP:
Complete cycle (I->
III) to be run.
I)
Context (deep magnetogram) SP map of surrounding
quiet-Sun region:
Time per exposure:
19.2 s (12 waveplate rotations),
FOV along slit:
164 arcsec,
Slit scan sampling:
0.16 arcsec,
Time for map area:
1940 s (101 steps=16 arcsec).
II)
Fixed slit (normal mode) SP observations at map centre:
Time per exposure:
4.8 s (3 waveplate rotations),
FOV along slit:
164 arcsec,
Slit scan sampling:
0 arcsec,
Time for map area:
10800 s (2250 exposures).
III)
Context (deep magnetogram) SP map of surrounding
quiet-Sun region: (same as run I).
2)
SOT-BFI: Complete cycle (I->
III) to be run. If data rate permits:
Co-temporal with SP time series:
I)
Ca II H imaging at high cadence (~3-6 s?),
II)
CN-band imaging at high cadence (~3-6 s?),
III)
G-band imaging at high cadence (~3-6 s?).
However, if data rate is already large, then:
I)
Context CN-band and G-band images,
II)
Ca II H imaging at high cadence (~2-6 s?) co-temporal
with SP time series,
III)
Context CN-band and G-band images.
OPTIONAL (Data rate permitting)
3)
SOT-NFI: Photospheric dopplergrams in Fe I 5567.1 \AA +/- 0.045
\AA at high cadence (~4-6 s?). 2. 1)
SOT-SP:
Complete cycle (I->
III) to be run once a day (at the
very least, once every other day) as a sunspot transits
the solar disk.
I)
Fixed slit (normal mode) SP observations halfway
through leading penumbra (with rotation compensation
applied):
Time per exposure:
4.8 s (3 waveplate rotations),
FOV along slit:
164 arcsec,
Slit scan sampling:
0 arcsec,
Time for map area:
10800 s (2250 exposures).
II)
Context (normal mode) SP map of whole sunspot:
Time per exposure:
4.8 s (3 waveplate rotations),
FOV along slit:
164 arcsec,
Slit scan sampling:
0.16 arcsec,
Time for map area:
2500 s (500 steps = 80 arcsec).
III)
Fixed slit (normal mode) SP observations halfway
through trailing penumbra: (same as run I).
OPTIONAL (Data rate permitting)
2)
SOT-BFI: Ca II H imaging at high cadence (~4-6 s?) including the
entire sunspot and some surrounding quiet sun in FOV.
3)
SOT-NFI: Photospheric dopplergrams in Fe I 5567.1 \AA +/- 0.045
\AA at high cadence (~4-6 s?) including the entire
sunspot and some surrounding quiet sun in FOV.
Scientific Objectives: 1. OBJECTIVE: To study the differences between both photospheric and chromospheric oscillations associated with granules and intergranular lanes. SCIENCE JUSTIFICATION: Analysis of coarse-resolution TRACE UV imaging time series has shown that oscillations are present in the solar magnetic network at frequencies below the cutoff predicted by standard acoustic wave theory (see, e.g., Krijger et al. 2001). In this scenario such low-frequency waves should not propagate beyond the temperature minimum, but the phase behaviour associated with upward-propagating waves is observed in the outer atmosphere. The recent work of Bloomfield et al. (2006), comparing the variation of phase behaviour with the underlying magnetic field, suggests that these waves are magneto-acoustic slow modes while Jefferies et al. (2006) propose that they are transmitted through "magneto-acoustic portals" -- regions at the edge of supergranular convective cells where the acoustic cutoff frequency is reduced by the presence of inclined magnetic fields (Bel and
Leroy 1977). We aim to search for the locations where differing forms of waves enter the outer atmosphere through the investigation at high spatial resolution of both oscillation frequencies and amplitudes, in addition to the phase relations observed between the photosphere and chromosphere. 2. OBJECTIVE: To study the distribution of field inclinations in both bright and dark penumbral structures, any associated spatial differences in wave behaviour, and the centre-to-limb variation of these effects. SCIENCE JUSTIFICATION: Recent work using high spatial resolution ground-based imaging (Langhans et al. 2005) indicates that the dark cores of bright filaments harbour the most inclined fields in sunspot penumbrae while bright filaments have much less inclined fields. Currently, two competing theories exist to explain the observed fine structure of sunspot penumbrae: 1) the "uncombed" model of Solanki and
Montavon (1993), and 2) the "gappy" model of Spruit and
Scharmer (2006). The first theory proposes that the penumbral atmosphere contains flux tubes of nearly horizontal magnetic field with a less inclined magnetic field surrounding it, while the second proposes that the near-horizontal fields are located at magnetic cusp points lying above field-free regions of the atmosphere. These two theories should yield differing speeds and preferred directions of wave propagation associated with bright penumbral filaments, due to the different nature of the atmosphere underlying these structures (i.e., magnetic or non-magnetic). It is such behaviour that we aim to study in a sunspot at differing positions across the solar disk, using the technique of wave detection from full-Stokes spectropolarimetry of Bloomfield et al. (2007).
Other Instruments: COORDINATED 4)
SST:
SOUP full-Stokes 2-D spectropolarimetry in Fe I 6302 \AA.
