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Travis Metcalfe (NCAR)

An asteroseismic data-interpretation pipeline for Kepler. Travis Metcalfe (NCAR). the light goes in here,. and the answers come out here.”. “From a theorist’s perspective, – Art Cox. Schematic pipeline.

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Travis Metcalfe (NCAR)

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  1. An asteroseismic data-interpretation pipeline for Kepler Travis Metcalfe (NCAR)

  2. the light goes in here, and the answers come out here.” “From a theorist’s perspective, – Art Cox

  3. Schematic pipeline input global search local analysis output nnl, Teff, L, R SVD LM M, Z, Y, a, t parallel GA pulsation frequencies and other constraints ASTEC + ADIPLS optimal parameters, other model output teragrid bluegene desktop workstation

  4. Global search: parallel GA • Genetic algorithm probes a broad range of possible model parameters • 0.75 < Mstar< 1.75 0.002 < Zinit< 0.05 0.22 < Yinit < 0.32 1.0 <amlt< 3.0 • Finds optimal balance between asteroseismic and other constraints

  5. Fitting for stellar age • Large frequency spacing <Dn> decreases almost monotonically with age • Binary decision tree to fit age from the observed large frequency spacing • Calculates only radial modes until final step, scales surface effects Christensen-Dalsgaard (2004)

  6. Correcting for surface effects • Incomplete modeling of surface convection zone leads to systematic errors • Parameterize the offset, calibrate with solar data, apply homology scaling • For near-optimal models, this procedure is enough to correct b Hydri data Kjeldsen & Bedding (in prep.)

  7. Local analysis: SVD+LM • We use each GA result as an “initial guess” for the local analysis • SVD probes information content of the seismic and other observables • Levenberg-Marquardt method for optimization and error analysis Creevey et al. (2007)

  8. The Future • Apply to existing ground-based asteroseismic observations to calibrate the method – initially on Sun-as-a-star data, then for other stars. • Refine this objective automated pipeline using space-based asteroseismic data, allowing for hundreds of analyses simultaneously. • Provide on-demand model-fitting through the TeraGrid as a “Science Gateway” project? (input: frequency list, output: optimal model) IBM Bluegene/L system

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