1. September 17, 20072nd ARENA Conference Postdam1 Asteroseismology, from space and from the ground Benoît Mosser Observatoire de Paris/LESIA

2. September 17, 20072nd ARENA Conference Postdam2 Summary 1.Space-borne asteroseismology CoRoT results 2.Ground-based observations Current results 3.Future projects Space, network, Dome C 4.Comparison / complementarity and unique role of Dome C

3. September 17, 20072nd ARENA Conference Postdam3 Asteroseismology Age determination~ a few % Stellar radii (impact for exoplanet radii)~ a few % Composition Diagnostic of convective cores Depth of convection and of second Helium ionization zones Excitation mechanisms (convection) Rotation and internal structure Specification: eigenfrequency precision = 0.2  Hz  continuous observations (  > 80 %)  long duration (T > 2.5 months)

4. September 17, 20072nd ARENA Conference Postdam4 CoRoT launched on December 27 th, 2006 by Soyuz 2, from Baikonour, Kazakhstan low Earth polar orbit, 896 km altitude orbital period 6184 s (~1h43mn, 162  Hz) high precision photometry The CoRoT space mission has been developped and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA, Germany and Spain

5. September 17, 20072nd ARENA Conference Postdam5 CoRoT « Eyes » CoRoT eyes:  =0,  =6h50 and 18h50

6. September 17, 20072nd ARENA Conference Postdam6 CoRoT asteroseismology targets 7 B stars,including 1 known Beta Ceph,3 Be, 1 ecl. bin. 4 giants (G,F) 12 A stars including 4 known pulsators, 2 Am, 2 Ap, 2 eclips. Bin. 3 (early) F stars 4 solar-like puls. cand. 5-month long run on each target

7. September 17, 20072nd ARENA Conference Postdam7 CoRoT first observations February, Marchinitial run, 60 days April1st short run May, 11  Oct. 15 1st long run not yet completed Raw dataN0OK 1st correctionsN1OK Scientific dataN2not yet distributed Sensitivety0.6 ppm in 5 days, for mV=5.4as expected Duty cycle92% (6% lost in SAA)better than expected

8. September 17, 20072nd ARENA Conference Postdam8 Example of light curves A 6th mag F-type star showing daily variability below the 10 -3 level Typically 10  in 30 s

9. September 17, 20072nd ARENA Conference Postdam9 Light curve An 9th magnitude suspected delta Scuti showing beat phenomena at a few 10 -3

10. September 17, 20072nd ARENA Conference Postdam10 Light curve An 8th magnitude B star in an eclipsing binary

11. September 17, 20072nd ARENA Conference Postdam11 A 7th magnitude giant F star showing very low dispersion of ~10 -4 Quiet target

12. September 17, 20072nd ARENA Conference Postdam12 HD 49933 1st solar-like target, initial run, 60 days Simulations: Baudin et al. 06 Photon noise Granulation

13. September 17, 20072nd ARENA Conference Postdam13 HD 49933, observed Mosser et al. 2005, 10 days with HARPS, duty cycle ~ 23%

14. September 17, 20072nd ARENA Conference Postdam14  Scuti Example of an 8th magnitude delta Scuti observed with CoRoT. The red line illustrates common lowest detection limit from the ground.

15. September 17, 20072nd ARENA Conference Postdam15 Ground-based observations solar-like oscillations in solar-like stars - HARPS @ ESO 3.6-m - UCLES @ AAT - CORALIE @ Euler telescope - SOPHIE @ OHP + instruments @ SARG, McD, Okoyama, Lick Oscillation detection ٧ ~ 20 targets Mode identification ٧ for ~ 12 targets 2-sites observation ٧ 5 targets Network observation ٧ 1 target (Procyon) Stellar structure modelling ٧ ~ 2 targets Rotation, fine structure… ٧ insufficient precision Observations limited to a few days

16. September 17, 20072nd ARENA Conference Postdam16 Single/multi-sites observation

17. September 17, 20072nd ARENA Conference Postdam17 Proyon: network observations Arentoft et al.; Bedding et al, in preparation time series ~ 9 days January 2007: Multi-site campaign -AAT -Okoyama -TLS -OHP -NOT -SARG -ESO -Euler -McDonald -Lick Procyon mV = 0.4 2 Gyr 1.5 M sun 2.0 R sun

18. September 17, 20072nd ARENA Conference Postdam18 Procyon:network result Observation duration T Eigenfrequency precision  ~ 1 / T 0.5 Modelling precision varies as  Despite network observations, the expected gain for interior structure modelling is limited, due to a too limited observation duration From Matthews et al 2004.

19. September 17, 20072nd ARENA Conference Postdam19 KEPLER NASA; launch = nov 2008 High precision photometry a few fields reserved for asteroseismology CoRoT  Kepler : tel. 27 cm  95 cm orbitpolar  L2 + duty cycle in L2 - sensitivety (mV > 9), radiations in L2 ?exact scientific case for asteroseismology? 29-31 October 2007: First KASC workshop, Paris. The Kepler Asteroseismic Science Consortium (KASC) is an international consortium of researchers dedicated to the asteroseismic analysis of Kepler data.

20. September 17, 20072nd ARENA Conference Postdam20 MOST Microsatellite for asteroseismology Operated by the Canadian Space Agency since 2004 High precision photometry Best performance ~ 20 ppm  Many results on pulsators with large amplitudes  Not sensitive enough for asteroseismology of solar-like stars with solar-like oscillations (Procyon’s oscillations not detected)

21. September 17, 20072nd ARENA Conference Postdam21 SONG Project currently in phase 0 Danish asteroseismology centre, Aarhus University Network of 6 to 8 small telescopes (60  80 cm) Echelle spectrometer + iodine cell Expected schedule: 1 prototype for 2012 >> 2012

22. September 17, 20072nd ARENA Conference Postdam22 40-cm telescope: - solar-like oscillations in solar-like targets (type: F, G, K; class: IV & V) - red giants;  Scuti;  Dor; PMS (with vsin i < 20 km/s)  Scientific program:for more than 6 winters complementary to CoRoT Fourier Tachometer to be installed at Dome C Phase A completed Scientific Committee Th Appourchaux (France, pdt), C Catala (inst. scientist), S Charpinet (France), D Kurz (UK), Ph Mathias (France), A Noels (Belgium), E Poretti (Italy),

23. September 17, 20072nd ARENA Conference Postdam23 SIAMOIS 40-cm telescope small size, low cost, easy ‘antarctization’, dedicated to the projet Interferometer fiber fed Fourier Tachometer, operated at room temperature, monolithic interferometer, photon noise limited performance Data automatic pipeline reduction, telemetry: limited flow < 100 kb/day Phase A completed, April 2007

24. September 17, 20072nd ARENA Conference Postdam24 Space / Ground spaceground Observationphotometryspectrometry Max. degree2 3 Targets magnitude dim bright Main differences between space-borne and ground-based observations

25. September 17, 20072nd ARENA Conference Postdam25 Doppler / photometry Solar granulation noise

26. September 17, 20072nd ARENA Conference Postdam26 Granulation noise

27. September 17, 20072nd ARENA Conference Postdam27 l=3 modes l=3 modes visible in spectroscopy Small separation

28. September 17, 20072nd ARENA Conference Postdam28 Doppler / photometry Inversion 4 times more precise with Doppler data low frequency noise + l=3 modes  Gabriel et al 1998

29. September 17, 20072nd ARENA Conference Postdam29 Complementary observations Strömgren photometry T eff, log g, metallicity High resolution spectrometryT eff, log g, abundances Interferometryangular diameter Astrometrydistance Stellar radius determined with enough precision only for bright stars Complementary ground-based observations are necessary - to measure fundamental parameters - to improve the modelling

30. September 17, 20072nd ARENA Conference Postdam30 Comparison CoRoTKeplerSONGSIAMOIS 2 eyes diam = 12° 10° x 10° (Cygnus-Lyra) |  | < 30°  <  45° Duty cycle 92 %~ CoRoT~ 85 %~ 90 % 5-day perf. 0.6 ppm> 1.2 ppm2-20 cm/s Max obs. 5 months  4 years3 months Magnitude > 6> 9< 7 # targets 28Up to 40 : 4 yr Up to 160 : 1 yr Up to 1000 : 90 d > 30 # solar-like 47 Status In operationLaunch = 11/ 2008 Phase 0 Prototype > 2012 Phase A is OK 2012 at Dome C Instrument cost 65 M€> 6 M€ (6 tel)0.86 M€ (1 tel) 1.02 M€ (2 tel)

31. September 17, 20072nd ARENA Conference Postdam31 Clear sky fraction at Dome C Clear sky fraction > 90% during 84% of the time Average number of consecutive clear days: 6.8 days Clear sky fraction measured by Eric Aristidi (2006 winter)

32. September 17, 20072nd ARENA Conference Postdam32 Duty cycle Better performance at Dome C compared to a 6-site network (Mosser & Aristidi 2007, PASP)

33. September 17, 20072nd ARENA Conference Postdam33 Simulations F6V star, mV = 4.5, vsini = 5 km/s, 90-day long run Modelling: stochastic excitation + intrinsic damping (Anderson et al 1990)

34. September 17, 20072nd ARENA Conference Postdam34 Simulations F6V star, mV = 4.5, vsini = 5 km/s, 90-day long run Precision on the eigenfrequency measurement: 0.10 – 0.25  Hz (Libbrecht 1992)

35. September 17, 20072nd ARENA Conference Postdam35 Conclusion Space-borne observations = photometric observations CoRot unique results Keplernot primilarly specified for asteroseismology sensitivity for solar-like oscillations? very dim targets  uncertainty on fundamental parameters Ground-based observations = Doppler observations measurement of modes with degree l = 3 much less low frequency noise  much better inversion and modelling & observation of low mass stars Networkvery late schedule, complex organization Dome C= unique site for asteroseismology 3-month continuous observation with duty cycle ~ 90% High performance with a 40-cm collector Better performance than a 6-site network http://siamois.obspm.fr

36. September 17, 20072nd ARENA Conference Postdam36 Everything is OK for SIAMOIS Risk ٧ - CFHT/FTS; GONG helioseismic network - Scientific program Cost ٧ - Construction < 1 M€ - Running cost << network Logistics ٧ - Automatic instrument; simple setup - Limited operations; low data flow - Phase A completed - Scientists, engineers, SC at work! http://siamois.obspm.fr ٧

37. September 17, 20072nd ARENA Conference Postdam37 Budget SIAMOISNetwork Site1 siteAt least 6 sites for similar performance Construction860 ME~ 6 ME Running cost for 3 months ~ 750 kE / number of projects 600 kE (according to GONG, WET networks) Observation5 months / year12 months / year

38. September 17, 20072nd ARENA Conference Postdam38 SIAMOIS at Dome C Demanding site ?Project ~ spatial-like organization (but with human presence) Quasi automatic, simple setup Reduced mass, low power, very low telemetry Seeing ?Fibre = 5" on the sky No big telescope at Dome C ?Key science with a 40-cm telescope (or 2 telescopes) Only circumpolar targets ?Scientific program for more than 6 winterings Fourier tachometer ?As the helioseismic network GONG, as onboard SoHO and SDO Duty cycle ~ 90% !Scientific specification #1 : duty cycle > 85% Polar night = 3 monthsScientific specification #2 : 100-day long runs

39. September 17, 20072nd ARENA Conference Postdam39 Fourier tachometer Why a FT instead of an échelle spectrometer? Fourier Tachometer = best solution for - GONG (network helioseismology) - MDI (helioseismology onboard SoHO) - Velocity and Magnetic Imager, SDO FT: simple installation and setup at Dome C Echelle spectrometer (as HARPS) tel Current telescope at Dome C / Telescope available in the near future for long duration observation = dedicated small telescopes FT

40. September 17, 20072nd ARENA Conference Postdam40 Possible targets Observable targets (solar-like stars with solar-like oscillations) with SIAMOIS and a 40-cm telescope dedicated to the project

41. September 17, 20072nd ARENA Conference Postdam41 Planning & budget < 2006 principle: monolithic Fourier Tachometer 2007 thermo-mechanical analysis phase A 2008-2010 PDR FDR integration 2010-2011 tests summer campaign: Dome C 2012 First winterover at Dome C Budget ~ 860 k€ << budget for an equivalent 6-site network LESIA (Obs. Paris), IAS (Orsay), LUAN (Nice), OMP (Toulouse) + SESO

42. September 17, 20072nd ARENA Conference Postdam42 Performance Photon noise limited performance, SIAMOIS at Dome C, 40-cm telescope, 120 hours with 90 % duty cycle, mV = 4 SNR on circumpolar targets Mosser et al 2003

43. September 17, 20072nd ARENA Conference Postdam43 Fourier tachometer Another advantage: multiplex advantage  simultaneous observations of several targets First step: small telescope + FT Then: multi-targets observation = small telescopes + 1 FT

44. September 17, 20072nd ARENA Conference Postdam44 Duty cycle at Dome C Resulting duty cycle (bright targets) > 90% during 90 days Polar night = 100 nights

45. September 17, 20072nd ARENA Conference Postdam45 Asteroseismology after COROT 1 - single-site runs, short runs 2 - photometry, space-borne observations, MOST, 3 - spectrometry, ground-based observations Ground-based observations Bright stars Low mass stars Doppler signal  reduced granulation noise  modes l=3 for small separation Specification: eigenfrequency precision = 0.2  Hz  continuous observations (  > 80 %)  long duration (T > 2.5 months)

46. September 17, 20072nd ARENA Conference Postdam46 SIAMOIS