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Science From BiSON

Science From BiSON. Key Science Themes. Structure of the Deep Radiative Interior Sound Speed and Rotation. Origin and Influence of Solar Cycle. Origins of the Oscillations Mode excitation and damping; surface physics. Solar Mean Magnetic Field (SMMF). …Roger New & Balazs Pinter.

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Science From BiSON

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  1. Science From BiSON

  2. Key Science Themes • Structure of the Deep Radiative Interior • Sound Speed and Rotation • Origin and Influence of Solar Cycle • Origins of the Oscillations • Mode excitation and damping; surface physics • Solar Mean Magnetic Field (SMMF) …Roger New & Balazs Pinter

  3. Achieving our Goals • Specific Investigations • Many in collaboration • Lots of connectivity between investigations • Over-arching data preparation and analysis tasks

  4. Over-arching Tasks • Data calibration • Modelling/removal low-frequency footprint • Optimisation of data selection • Data preparation • Time series construction

  5. Time series construction Knitting a week of data together 10 hr 2 m/s Residual velocity (m/s) Time

  6. Over-arching Tasks • Data calibration • Modelling/removal low-frequency footprint • Optimisation of data selection • Data preparation • Time series construction • Gap filling • Public dissemination of data

  7. Over-arching Tasks • Mode parameter extraction • Development of fitting techniques

  8. Changes Across the Mode Spectrum Low Frequency High Frequency l=2/0 mode pairs in BiSON data

  9. Over-arching Tasks • Mode parameter extraction • Development of fitting techniques • Development and application of artificial data • Monte-Carlo applications vital for testing analysis(at all stages…)

  10. Key Science Themes • Structure of the Deep Radiative Interior • Origin and Influence of Solar Cycle • Origins of the Oscillations • Solar Mean Magnetic Field (SMMF)

  11. Structure of the Deep Radiative Interior • Sound speed and rotation profiles • New modes at low frequencies • More accurate frequency extraction • Removal of effects of surface layers, i.e., peak and multiplet asymmetry, solar-cycle shifts • Comparative/correlation analyses of different data vital

  12. Origin and Influence of Solar Activity Cycle • Study of mode parameter variations in greater detail • Dependence on angular degree, l Dependence on frequency • Careful comparison between datasets • What do differences between sets tell us? • Inform models of variations in mode properties

  13. Origins of the Oscillations • Mode excitation and damping • Using observation to inform models • Origin of large or unusual excitations: linking the interior to the surface • Tracking mode phase as an important tool

  14. Origins of the Oscillations • Surface Physics • Resonant peak asymmetry and phase shifts: influence of granulation • Height dependence in photosphere • SMMF

  15. Solar Cycle Variations Chaplin et al., in preparation Cycle 23 Cycle 22

  16. Solar Cycle Variations Howe et al., 2003, ApJ, 588, 1204 Frequency BiSON GONG Power density Linewidth

  17. An Unusual Excitation that Bucks the Long-Term Trend What was the cause? Chaplin et al., 2003, ApJ, L582, 115

  18. Needles in a Haystack: Modes at Low Frequencies Predicted  9 years of BiSON data

  19. Low-Frequency p Modes Chaplin et al., 2002, MNRAS, 336, 979

  20. Importance of removal of surface activity Inversion for sound speed with fractional radius 0.002 ...with ‘raw’ BiSON frequencies 0.001 -0.001 -0.002 0.2 0.4 0.6 0.8 1.0 Inversions courtesy A. Kosovichev

  21. Importance of removal of surface activity Inversion for sound speed with fractional radius 0.002 ...with ‘corrected’ BiSON frequencies 0.001 -0.001 -0.002 0.2 0.4 0.6 0.8 1.0 Inversions courtesy A. Kosovichev

  22. Rotation Inversions Effect of adding more low-l splittings at low frequency Artificial data: 400 nHz input

  23. Low-Frequency p Modes BiSON minus SACLAY model frequencies Chaplin et al., 2002, MNRAS, 336, 979

  24. Frequency Uncertainties Chaplin et al., 2002, MNRAS, 330, 731

  25. Low-Frequency p Modes GOLF minus BiSON frequencies Chaplin et al. 2002, 336, 979; Bertello et al., 2000a, b

  26. Frequency Uncertainties Scale as T½ Perform analysis to find  for model where errors scale as  T  Chaplin et al., 2002, MNRAS, 330, 731

  27. Mode Lifetimes Chaplin et al., 2002, MNRAS, 330, 731

  28. High Frequency Spectrum Solid: GOLF Dashed: BiSON

  29. High-Frequency Peaks GOLF blue wing minus BiSON

  30. Low-Resolution BiSON Spectrum Gear-frequency artefact

  31. Rising/Falling Parts of Cycle: Freq vs. KPMI

  32. Total Solar Irradiance & p-Mode Frequency Shifts

  33. l=2 Multiplet Frequency Asymmetries No magnetic field Now apply B field... Power m =0 Frequency m =+2 m =-2

  34. l=2 Multiplet Frequency Asymmetries Pattern becomes asymmetric Power m =0 Frequency m =+2 m =-2

  35. l=2 Multiplet Frequency Asymmetries Pattern asymmetry given by: Power an m =0 Frequency m =+2 m =-2

  36. l=2 Multiplet Frequency Asymmetries GOLF BiSON Chaplin et al., MNRAS, in press

  37. l=2 Multiplet Frequency Asymmetries Chaplin et al., MNRAS, in press

  38. l=2 Multiplet Frequency Asymmetries BiSON: asymmetric minus symmetric multiplet model frequency 864-d data set

  39. Low-l Peak Asymmetries BiSON: asymmetric- minus symmetric-peak model frequency 864-d data set

  40. Rotational Splittings (Synodic) Chaplin et al., 2001, MNRAS, 327, 1127

  41. Impact of Fitting Model Different assumed component height ratios cf. Chaplin et al., 2001, MNRAS, 327, 1127

  42. Sidereal Splittings from 3456-d spectrum Median 431.8  2.7 nHz Unweighted 430.5  2.8 nHz Weighted 430.1  1.2 nHz

  43. Collaboration

  44. Collaboration

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