Context The hounds The hares Preliminary results SpaceInn hare-and-hounds exercise D. R. Reese, W. J. Chaplin, G. R. Davies, A. Miglio and many hounds December 5, 2014 Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Next steps Context determining accurate stellar parameters through asteroseismology is fundamental for the PLATO 2.0 mission characterising exoplanets studying galactic populations and history understanding stellar evolution Reese et al. SpaceInn hare-and-hounds exercise Context The hounds The hares Preliminary results Next steps Context According to Gough (1985) there are 3 ways of inverting helioseismic data: “repeated execution of the forward problem” (i.e. search in parameter space, or “forward modelling”) analytical methods (asymptotic methods, glitch fitting) formal inversion techniques this also applies to asteroseismology. However: greater uncertainties on “classical parameters” (Teff , [Fe/H], L, v sin i ...) fewer number of available frequencies Reese et al. SpaceInn hare-and-hounds exercise Context The hounds The hares Preliminary results Context it becomes important to compare these methods accuracy (precise results and realistic error bars) computational cost hare-and-hounds exercises is a good way of carrying out such a comparison Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Next steps First SpaceInn hare-and-hounds exercise Motivations test how accurately fundamental stellar parameters can be retrieved from individual frequencies compare grid-based techniques to glitch-fitting methods for characterising the convection zone Reese et al. SpaceInn hare-and-hounds exercise Context The hounds The hares Preliminary results The hounds Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results The hounds Group 1 uses grid modelling to obtain best fitting models and associated parameters global parameters: M, R, RR ρ, τ = 0 drc , age etc. convection zone: RCZ , τCZ Reese et al. Group 2 applies glitch fitting strategy to find RCZ , τCZ SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results The hounds Group 1 W. Ball S. Basu Group 2 I. Brandão J. Christensen-Dalsgaard S. Deheuvels H. M. Antia and K. Verma S. Hekker H. R. Coelho Y. Lebreton G. Houdek A. Mazumdar et al. A. Mazumdar et al. T. S. Metcalfe M. J. P. F. G. Monteiro I. W. Roxburgh I. W. Roxburgh S. Basu A. Serenelli V. Silva Aguirre D. Stello Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results The hares Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results The hares Team work A. Miglio: produce models D. R. Reese: adjust models and calculate frequencies W. J. Chaplin & G. R. Davies: prepare “observed” data Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results The data various classic parameters (Teff , L, [Fe/H]) we assume Gaia-quality parallax for the luminosity seismic indices: ∆ν, νmax (these are purely indicative) individual frequencies bypass mode parameter extraction and assume frequencies are unbiased Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results The hares Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Surface effects offset at high frequencies, caused by near-surface layers ways this can be implemented truncate model apply different boundary conditions modify near-surface structure use different atmosphere apply non-adiabatic calculations Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Surface effects offset at high frequencies, caused by near-surface layers ways this can be implemented truncate model apply different boundary conditions modify near-surface structure use different atmosphere apply non-adiabatic calculations Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Surface effects offset at high frequencies, caused by near-surface layers ways this can be implemented truncate model apply different boundary conditions modify near-surface structure use different atmosphere apply non-adiabatic calculations Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Surface effects offset at high frequencies, caused by near-surface layers ways this can be implemented truncate model apply different boundary conditions modify near-surface structure use different atmosphere apply non-adiabatic calculations Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Next steps Other factors 12 %WTPYRH IX EP the stellar mixture possibilities: GN93, GS98, AGS05, AGSS09 diffusion is it present? does it apply to all elements? Logarithmic abundance (dex) 10 8 6 4 2 0 overshoot 0 20 40 Atomic number Reese et al. SpaceInn hare-and-hounds exercise 60 80 Context The hounds The hares Preliminary results Other factors the stellar mixture possibilities: GN93, GS98, AGS05, AGSS09 diffusion is it present? does it apply to all elements? 1MGLEYH IX EP overshoot Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Preliminary results Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Preliminary results Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Preliminary results Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Preliminary results Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Preliminary results Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Preliminary results Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Preliminary results Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Glitch fitting Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Next steps Glitch fitting 3 70 l=0 l=1 l=2 Percentage of Realisations 60 δν (µHz) 2 1 0 -1 -2 2400 50 40 30 20 10 0 2800 3200 3600 4000 ν (µHz) Reese et al. 0 1000 2000 Acoustic depth τ (s) SpaceInn hare-and-hounds exercise 3000 Context The hounds The hares Preliminary results Glitch fitting Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Glitch fitting Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Glitch fitting Reese et al. SpaceInn hare-and-hounds exercise Next steps Context The hounds The hares Preliminary results Next steps still waiting for final results before doing full processing carry out future rounds to test other quantities (He content, He ionisation etc.) Reese et al. SpaceInn hare-and-hounds exercise Next steps
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