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Sunspot Studies in Oslo

Sunspot Studies in Oslo. Nils Brynildsen, Per Maltby, Terje Fredvik and Olav Kjeldseth-Moe Institute of Theoretical Astrophysics University of Oslo. Program History. Sunspot studies with SOHO instruments from 05/1996

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Sunspot Studies in Oslo

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  1. Sunspot Studies in Oslo Nils Brynildsen, Per Maltby, Terje Fredvik and Olav Kjeldseth-Moe Institute of Theoretical Astrophysics University of Oslo

  2. Program History • Sunspot studies with SOHO instruments from 05/1996 • Purpose: To study the transition region and corona above spots, particularly the fast down flows into sunspot umbrae observed with HRTS • Extended to sunspot plumes, and 3 min oscillations in the sunspot chromosphere and transition region • O_SPOT – studies run between May 1996 and present • A total of 115 spots observed on 190 days • All O_SPOT data are processed into intensity and velocity maps • Results presented in papers, talks, posters and proceedings

  3. Oslo Sunspot Studies O_SPOT1 – raster of (4) wide slit images at three wavelengths O_SPOT2 – limited spatial extent, but many lines, reasonably high cadence raster O_SPOT3 - coarse raster to replace O_SPOT1 O_SPOT4 - a “sit and stare” study for rapid time variations O_SPOT5 - large FOV, reasonable cadence, raster (incomplete area coverage, stripes) --------------------------------------------- O_SPOT10 – GIS study for sunspot oscillations O_SPOT11 – NIS study for sunspot oscillations

  4. Oslo Sunspot Studies (2) Study Spectro- Slit Step Number of FOV of Exp. Cadence Name meter # size Locations/ one rst. time (duration) (as) Rasters (as^2) (s) (m:s) ============================================== O_SPOT1 NIS 6 50 4/4 240x240 10 2:04 O_SPOT2 NIS 4 2 60/1 120x120 20 22:36 O_SPOT3 NIS 5 8 30/1 240x240 8 6:20 O_SPOT4 NIS 3 drift 150/1 4x51 5 20:30 O_SPOT5 NIS 4 4 60/1 240x240 10 26:30 ---------------------------------------------------------------- O_SPOT10 GIS 2 drift 145/6 11x4 17 45:50 O_SPOT11 NIS 4 drift 250/1 13x120 10 60:00 ============================================== Studies marked drift have step size 0 arc-sec. and no rotational comp. Number of locations marks number of exposures defined as a single raster Solar drift rate x raster duration defines extent of raster in x-direction

  5. Wavelength list Ion l (Å) T(K) #1 #2 #3 #4 #5 #10 #11 ===================================== He I 522 10 000 x He I 584 10 000 x x x x F x O III 599 95 000 x x x u O VI 554 175 000 x x x x l x O V 629 240 000 x x x x x l x Ne VI 562 430 000 x x x x Mg VIII 315 810 000 x G Mg IX 368 960 000 x x x x x I x Fe XIV 334 1 900 000 x S Fe XVI 360 2 700 000 x x x x

  6. Number of spots/runs

  7. - A 50 arc sec overlapping area, with ~30 s and ~2 min cadence - Clear and significant changes over 5 min time periods. Also perceptible changes over time spans of ~2 min.

  8. Mapping of • plumes • - Located above the • white light spot • - I > 5 x <I>  i.e. • yellow contour • - Max visibility at • 0.25 MK – do not • occur in corona, • i.e. cool • - Down flows into • the spots in TR • - No corresponding • up-flows • - No systematic • flows in corona • Up-flows in • extended area? • (large raster)

  9. NIS Oscillations

  10. GIS/NIS Oscillations

  11. Data reduction of O_SPOT data All CDS data are corrected using standard CDS software, transformed to absolute intensity, and processed may encompass the following: -- Intensity and velocity maps from line profiles fitted to Gaussians. Blends removed before fitting. -- Routines for conditional probability analysis used on selected emission lines. -- Power spectra of relative integrated line intensities calculated for spectral lines to study the 3 minute oscillations. -- CDS data are often co-aligned and compared with data from SUMER, MDI or TRACE.

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