Science From BiSON

Key Science Themes Structure of the Deep Radiative Interior

Sound Speed and Rotation

Origin and Influence of Solar Cycle

Solar Mean Magnetic Field (SMMF)

Origins of the Oscillations Mode excitation and damping; surface physics

…Roger New & Balazs Pinter

Achieving our Goals

Specific Investigations Many in collaboration Lots of connectivity between investigations

Over-arching data preparation and analysis tasks

Over-arching Tasks

Modelling/removal low-frequency footprint Optimisation of data selection

Data calibration

Data preparation

Time series construction

Time series construction

Knitting a week of data together

Time

Resid

ual velo

cit

y (

m/s

)

10 hr

2 m/s

Over-arching Tasks

Modelling/removal low-frequency footprint Optimisation of data selection

Data calibration

Data preparation

Time series construction

Gap filling Public dissemination of data

Over-arching Tasks Mode parameter extraction

Development of fitting techniques

Changes Across the Mode Spectrum

=2/0 mode pairs in BiSON data

Low Frequency

High Frequency

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…)

Key Science Themes Structure of the Deep Radiative Interior

Origin and Influence of Solar Cycle

Solar Mean Magnetic Field (SMMF)

Origins of the Oscillations

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

Origin and Influence of Solar Activity Cycle

Study of mode parameter variations in greater detail Dependence on angular degree,

Dependence on frequency

Careful comparison between datasets What do differences between sets tell us?

Inform models of variations in mode properties

Origins of the Oscillations Mode excitation and damping

Origin of large or unusual excitations: linking the interior to the surface

Using observation to inform models

Tracking mode phase as an important tool

Origins of the Oscillations Surface Physics

Height dependence in photosphere

Resonant peak asymmetry and phase shifts: influence of granulation

SMMF

Solar Cycle Variations

Cycle 23

Cycle 22

Chaplin et al., in preparation

Solar Cycle Variations

Frequency

Linewidth

Power density

BiSONGONG

Howe et al., 2003, ApJ, 588, 1204

What was the cause?

Chaplin et al., 2003, ApJ, L582, 115

An Unusual Excitation that Bucks the Long-Term Trend

Needles in a Haystack: Modes at Low Frequencies

Predicted

9 years of BiSON data

Low-Frequency p Modes

Chaplin et al., 2002, MNRAS, 336, 979

Importance of removal of surface

activity

0.2 0.4 0.6 0.8 1.0

0.0020.001

-0.001-0.002

cc /

Rr /

Inversions courtesy A. Kosovichev

...with ‘raw’ BiSON frequencies

Inversion for sound speed with fractional radius

0.2 0.4 0.6 0.8 1.0

0.0020.001

-0.001-0.002

cc /

Rr /

Inversions courtesy A. Kosovichev

Importance of removal of surface

activityInversion for sound speed with fractional radius

...with ‘corrected’ BiSON frequencies

Rotation Inversions

Effect of adding more low- splittings at low frequency

Artificial data: 400 nHz input

Low-Frequency p Modes

Chaplin et al., 2002, MNRAS, 336, 979

BiSON minus SACLAY model frequencies

Frequency Uncertainties

Chaplin et al., 2002, MNRAS, 330, 731

Low-Frequency p Modes

GOLF minus BiSON frequencies

Chaplin et al. 2002, 336, 979; Bertello et al., 2000a, b

Frequency Uncertainties Scale as T ½

Perform analysis to find for model where errors scale as T

Chaplin et al., 2002, MNRAS, 330, 731

Mode Lifetimes

Chaplin et al., 2002, MNRAS, 330, 731

High Frequency SpectrumSolid: GOLF Dashed: BiSON

High-Frequency PeaksGOLF blue wing minus BiSON

Low-Resolution BiSON Spectrum

Gear-frequency artefact

Rising/Falling Parts of Cycle: Freq vs. KPMI

Total Solar Irradiance & p-Mode Frequency Shifts

=2 Multiplet Frequency Asymmetries

m =+2m =0m =-2 Frequency

Power

No magnetic field Now apply B field...

=2 Multiplet Frequency Asymmetries

m =+2m =0m =-2 Frequency

Power

Pattern becomes asymmetric

=2 Multiplet Frequency Asymmetries

m =+2m =0m =-2 Frequency

Power

Pattern asymmetry given by:

022 )(21

mmmna

an

=2 Multiplet Frequency Asymmetries

BiSON GOLF

Chaplin et al., MNRAS, in press

=2 Multiplet Frequency Asymmetries

Chaplin et al., MNRAS, in press

=2 Multiplet Frequency Asymmetries

BiSON: asymmetric minus symmetric multiplet model

frequency)( 222

1 mmn

864-d data set

Low- Peak Asymmetries

BiSON: asymmetric- minus symmetric-peak model frequency

864-d data set

Rotational Splittings (Synodic)

Chaplin et al., 2001, MNRAS, 327, 1127

Impact of Fitting Model

Different assumed component height ratios

cf. Chaplin et al., 2001, MNRAS, 327,

1127

Sidereal Splittings from 3456-d spectrum

Unweighted 430.5 2.8 nHz

Weighted 430.1 1.2 nHz

Median 431.8 2.7 nHz

CollaborationStructureof solarinterior

Origins ofSolarCycle

Excitationand

DampingSMMF

Origins of TSI variationsBiSON/VIRGO (Fröhlich &

Appourchaux)

Long-term Solar-Cycle Trends(Basu)

Unusual High-Excitation Events(Toutain)

Rotation Modulation of RadialModes (Anderson & Leifson)

Influence of Magnetic Fields(Erdelyi)

Studies of the SMMF (Hoeksema)

Collaboration

CollaborationStructureof solarinterior

Origins ofSolarCycle

Excitationand

DampingSMMF

PHOEBUS (multi-institutions)

Rotation of the Solar Core(Sekii)

Extraction of RotationalSplittings (Appourchaux)

l=2 Asymmetry (ORSAY)

Modelling Excitation/Damping(Gough & Houdek)

BiSON/GONG Comp. & SolarCycle (Howe, Komm & Hill

BiSON/GOLF Comp. & SolarCycle (Jimenez-Reyes & Garcia)

Collaboration