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SIAMOIS Sismomètre Interferentiel A Mesurer les Oscillations des Intérieurs Stellaires

SIAMOIS Sismomètre Interferentiel A Mesurer les Oscillations des Intérieurs Stellaires An asteroseismic network with 1 site... in Antarctica. Benoît Mosser , Tristan Buey, Claude Catala

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SIAMOIS Sismomètre Interferentiel A Mesurer les Oscillations des Intérieurs Stellaires

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  1. SIAMOIS Sismomètre Interferentiel A Mesurer les Oscillations des Intérieurs Stellaires An asteroseismic network with 1 site... in Antarctica Benoît Mosser, Tristan Buey, Claude Catala Michel Auvergne, Thierry Appourchaux, Annie Baglin, Caroline Barban, François Bouchy, Stéphane Charpinet, Marc-Antoine Dupret, Marie-Jo Goupil, Jean-Pierre Maillard, Eric Michel, Reza Samadi, François-Xavier Schmider, Frédéric Thévenin, Gérard Vauclair et al. Observatoire de Paris/LESIA, IAP, IAS, UNSA/LUAN, OMP/LATT, OCA SONG workshop

  2. Which program in asterosismology after COROT ? Dome C in Antarctica SIAMOIS: principle SIAMOIS: performances (/ SONG) Project: organisation, science SUMMARY SONG workshop

  3. Ground-based observations, 2006 Ground-based asteroseismic observations remain limited by the window effect SONG workshop

  4. Ground-based observations, 2006 Even with bi-sites observations Kjeldsen et al 2005 Continuous observations are required for precise structure modelling SONG workshop

  5. In 2009, end of COROT will have done a considerable work ! And after that ??? SONG workshop

  6. Photometry / spectrometry • Spectrometry less sensitive to granulation than photometry • Visibility of l = 3 modes enhanced about ~ 3 times in spectometry • Small separation between modes with degrees 1 et 3 Ground-based measurements = spectrometric observations Necessarily: continuity, long duration network or Antarctica SONG workshop

  7. Dome C • Concordia station, Italy + France • 75°06’ south, 123°21’ east • Average temperatures • - 40°C in summer • - 60°C in winter • Slow wind • Rare precipitations: • 2 to 10 cm snow/year • Polar night: 3 months SONG workshop

  8. Duty cycle > 90 % during 3 months in winter (K. Agabi) SONG workshop

  9. (First) observations at Dome C • Specifications for observations at Dome C • integrated project • has to be fully tested before installation in Antarctica • with limited setup • small size telescope • pioneering project • project has to be fully automatic, ~ spatial condition • human intervention limited to routine, or survival • mass, power, telemetry: limited values • scientific programme has to be • ambitious • unfeasible elsewhere • to make sense after COROT SONG workshop

  10. Observations at Dome C • IPEV (Institut Paul-Emile Victor) • - in charge of the Concordia base; wintering since 2005 • - supervises scientific projects • INSU (National Institute for Astronomy)/ Antarctic group • - promotes observations at Dome C • - has to identify pioneering projects in astronomy • PNPS (National programme for stellar physics) • - promotes the rapid development of an asteroseismometer at Dome C -1- dedicated asteroseismometer with a small size telescope first wintering in 2010 -2- 2-m class telescope + spectropolarimeter SONG workshop

  11. Doppler asteroseismometry • Principle (Bouchy et al. 2001): photon noise limited performances • An asteroseismometer has to be extremely stable and efficient • - quality factor Q • - number of photoelectronsNe • Q depends on: • - the spectral type and rotation of the star • the instrument • GS: grating spectrometer • FS: Fourier Transform spectrometer SONG workshop

  12. Stellar quality factor • The quality factor gives a measure of the: • number • depth • width • of the stellar lines • Q # dln A /dln l • Cool stars are favored • Better performances in the blue part of the visible spectrum SONG workshop

  13. Seismology with a GS The real quality factor depends on the resolution R of the spectrometer A high resolution requires a narrow entrance slitas well as a large spectrometer R # f / d Grating spectrometer: necessarily a large instrument SONG workshop

  14. FS: seismometry by TF Fourier transform Seismometry The Doppler signal is searched in the interferogram of part of the stellar spectrum SONG workshop

  15. Sismometry by TF FT seismometry successfully tested with the FTS at CFHT Procyon Mosser et al. 1998, A&A 340, 457 Jupiter Mosser et al. 2000, Icarus 144, 104 • FTS at CFHT: scan of one fringe • Dedicated instrument: simultaneous scan of the fringe signal SONG workshop

  16. FS: quality factor avec • (Mosser et al. 2003, PASP 115, 990) • Q increases with • wavenumber s0 • working path difference dopt • fringe contrastC • A high fringe contrast C requires a narrow bandwidth • … in contradiction with the specification on Ne It is necessary to observe with a post-dispersive device SONG workshop

  17. FS: post - dispersion Fourier transform seismometry with post-dispersion The Doppler signal is searched in the interferogram of each spectral element defined by the post-dispersion SONG workshop

  18. FS / GS GS: smaller and simpler instrument, monolithic interferometer, no moving parts  possible installation and setup in Antarctica SONG workshop

  19. Antarctic / network Complementaryprojects SONG workshop

  20. Performances: GS / FS GS: HARPS (ref = ThAr lamp) R ~ 90000 FS: SIAMOIS; post-dispersion providing a spectral resolution R~ 1000. GS > FS if reference = ThAr lamp (Mosser et al. 2003) GS ~ FS if reference = iodine cell SONG workshop

  21. GS: performances at Dome C • Photon noise limited performances • SIAMOIS, at Dome C, 40-cm telescope, • 120 hours with 95% duty cycle, mV = 4 • ‘‘SNR’’ on circumpolar targets SONG workshop

  22. Targets Observable targets with SIAMOIS and a 40-cm telescope dedicated to the project COROT • 40-cm telescope: • - 7 targets, type: F, G, K class: IV & V - many red giants; d Scuti (v sin i < 20 km/s) • Scientific programme for more than 6 winterings SONG workshop

  23. Targets 1) K, G, F, class IV & V targets SONG workshop

  24. Targets 3) delta-Scuti 1) K, G, F, class IV & V targets 2) red giants SONG workshop

  25. Instrument • 40-cm telescope low cost, easy ‘antartization’, dedicated to the project • Interferometer monolithic instrument • no moving parts, reduced size • fiber fed • Post-dispersion efficiency, photon noise limited performances SONG workshop

  26. Planning • 2004 • design • 2006 • thermo-mechanical analysis • 2007 • PDR • FDR • 2008 • integration • 2009 • tests • summer campaign: Dome C • 2010 • - first winterover at Dome C • Laboratories: LESIA (Obs. Paris), IAS (Orsay), LUAN (Nice), LATT (Toulouse) SIAMOIS Interferometer JP Amans, GEPI, Obs Paris SONG workshop

  27. Dome C: a unique site for asterosismology 3-month continuous observation with duty cycle ~ 90% A specific scientific program after High performances with a 40-cm collector Pioneering project at Dome C FT seismometry: suitable concept for installation and setup at Dome C Multiplex advantage of FT spectrometry Conclusion siamois ‘‘Big science’’  at Dome C with a budget < 1 ME SONG workshop

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