* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download targets - siamois
Perseus (constellation) wikipedia , lookup
Space Interferometry Mission wikipedia , lookup
Kepler (spacecraft) wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Hubble Space Telescope wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Astronomical seeing wikipedia , lookup
Stellar kinematics wikipedia , lookup
European Southern Observatory wikipedia , lookup
History of the telescope wikipedia , lookup
Astronomical spectroscopy wikipedia , lookup
Leibniz Institute for Astrophysics Potsdam wikipedia , lookup
James Webb Space Telescope wikipedia , lookup
Hubble Deep Field wikipedia , lookup
Jodrell Bank Observatory wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Astrophotography wikipedia , lookup
Spitzer Space Telescope wikipedia , lookup
Ground-based Doppler asteroseismology after CoRoT and Kepler Benoît Mosser, for the SIAMOIS team http://siamois.obspm.fr/ Catania 09/08 SIAMOIS 1/26 Asteroseismology What do we need after CoRoT, that Kepler, and hopefully PLATO, will not provide? Doppler velocity (Space-borne observations are photometric) Provide additional information More precise for structure inversion Ground-based High duty cycle, continuous measurements Dome C in Antarctica provide excellent observation conditions Scientific objectives require the observation of a few bright targets for convergence of very precise measurements observed with a small collector Asteroseismic program at Dome C simple, robust, with an easy setup Catania 09/08 SIAMOIS 2/26 Spectrometry / Photometry Catania 09/08 SIAMOIS 3/26 Granulation noise Catania 09/08 SIAMOIS 4/26 HD 49933 CoRoT/HARPS data Mosser et al 2005 Appourchaux et al 2008, in press Catania 09/08 SIAMOIS 5/26 Additional Information l =3 modes Granulation noise at low frequency Catania 09/08 not visible in photometry SIAMOIS 6/26 Large and small separations Small separation Dn1-3 Catania 09/08 SIAMOIS 7/26 Catania 09/08 SIAMOIS Low low-frequency noise + l=3 modes Courtesy Thierry Appourchaux Doppler / photometry on the Sun Inversion 4 times more precise with Doppler data 8/26 High duty cycle, long duration time series Catania 09/08 SIAMOIS 9/26 Clear sky fraction at Dome C Clear sky fraction (naked eye, Eric Aristidi, 2006 winter) Clear sky fraction > 90% during 84% of the time Average number of consecutive clear days: 6.8 days Catania 09/08 SIAMOIS 10/26 Duty cycle: h_sun = -4° Mosser & Aristidi 2007 Bad weather Operations: telescope derotation… Sky brightness Resulting duty cycle (bright targets) > 90% during 90 days Catania 09/08 SIAMOIS 11/26 Duty cycle: h_sun = -8° Catania 09/08 SIAMOIS 12/26 Duty cycle: h_sun = -13° Catania 09/08 SIAMOIS 13/26 Duty cycle at Dome C [GONG data] Performance at Dome C compared to a 6-site network as GONG (Mosser & Aristidi 2007, PASP) Catania 09/08 SIAMOIS 14/26 Scientific program Catania 09/08 SIAMOIS 15/26 Scientific program High-precision determination of the interior structure of nearby stars • Age determination ~ a few % • Stellar radii (impact for exoplanet radii) ~ a few % • Composition Comparative study: photometry / Doppler • Convection, damping, excitation mechanisms • Diagnostic of convective cores; depth of convection and of second Helium ionization zones Classical pulsators • Non-linear physics, saturation effects, mode coupling • Stochastically excited modes Slowly rotating targets • Rotation Catania 09/08 SIAMOIS 16/26 Simulations l= 2 0 3 1 F6V star, mV = 4, vsini = 5 km/s, 90-day long run Modelling: stochastic excitation + intrinsic damping + SIAMOIS characteristics and performance Catania 09/08 SIAMOIS 17/26 Simulations Longer lifetimes at low frequency clear multiplets l= 2 0 3 1 F6V star, mV = 4.5, vsini = 5 km/s, 90-day long run Precision on the eigenfrequency measurement: 0.10 – 0.25 mHz (Libbrecht 1992) Catania 09/08 SIAMOIS 18/26 Targets with a 40-cm telescope Observable solar-like stars with p-mode oscillations for a dedicated 40-cm telescope [for all selected targets SNR > 6 in 5 nights] • 40-cm telescope: - 7 bright targets, type: F, G, K class: IV & V - many red giants; d Scuti (v sin i < 20 km/s) Enough targets for completing the scientific program in 3 to 6 winterings Catania 09/08 SIAMOIS 19/26 Targets with a 40-cm telescope Long duration observation dedicated collector Observable targets (solarlike stars with solar-like oscillations) with SIAMOIS and a 40-cm telescope dedicated to the project Catania 09/08 SIAMOIS 20/26 With a 2-m telescope • dimmer solar-like targets (e.g. star with exoplanets; Sylvie Vauclair’s cancelled talk) • ro Ap + any target with • g doradus vsini < 20 km/s • d scuti mV < 10.5 • red giants Out of the scope of SIAMOIS: white dwarfs and subdwarf B stars (too faint magnitude (1319), with a limited number of too broad spectral lines) Don Kurtz’talk; Gerard Vauclair’s cancelled presentation For bright targets, dedicated small telescope For dimmer targets, shared larger telescope Catania 09/08 SIAMOIS 21/26 Conclusion Catania 09/08 SIAMOIS 22/26 Space / Ground space ground Observation photometry spectrometry Max. degree 2 Targets magnitude faint 3 bright v sin i - < 20 km/s Inversion 4 times more precise Photometry on faint targets, without any other precise measurements Statistical approach Precise Doppler measurements on nearby bright targets + convergent measurements (interferometry, high resolution spectrometry…) Determination of a sample of stellar standards Insights into the physical laws governing stellar interiors Catania 09/08 SIAMOIS 23/26 Comparison CoRoT Kepler PLATO SONG SIAMOIS 2 eyes diam = 12° 10° x 10° (Cygnus-Lyra) 20° x 20° |d| < 30° 4 sites full sky d < -45° Duty cycle 92% ~ 100% ~ 100% (L2) ~ 85% ~ 90% 5-day perf. 0.6 ppm ~ ppm ~ ppm Max obs. 5 months < 4 years > 4 years 3 months 3 months Magnitude >6 >9 < 13 <7 <7 # targets 28 Up to 40 : 4 yr Up to 160 : 1 yr Up to 1000 : 90 d 100 000 >100 > 30 # solar-like 4 ~ few 100 In operation Launch = 04/ 2009 Status Instrument cost Catania 09/08 65 M€ 2-20 cm/s 7 Assessment study at ESA Phase A funded Prototype > 2011 Network > 2014 Phase A is OK 2013 at Dome C Class M project > 12 M€ (6 tel) 0.86 M€ (1 tel) 1.02 M€ (2 tel) SIAMOIS 24/26 Doppler asteroseismology Space-borne observations = photometric observations MOST, CoRoT, Kepler, Brite, PLATO… Ground-based observations = Doppler observations - less noise at low frequency - measurement of modes up to degree l= 3 - observation of bright stars very precise inversion and modelling Next talk - looking in great detail into nearby stars - identifying the physical processes Dome C = unique site for asteroseismology 3-month continuous observation with duty cycle ~ 90% * High performance with a 40-cm collector * Scientific program with 40-cm and 2-m collectors http://siamois.obspm.fr Catania 09/08 Granada:16 - 18/04/ 08 SIAMOIS 25/26 Additional material Catania 09/08 SIAMOIS 26/26 Perspectives Asteroseismology requires uninterrupted long-duration time series! 1 dedicated 40-cm telescope: - first season observation - fiber FOV = 5’’ (>> seeing) stellar magnitude < 5 for solar-like oscillations < 7 for classical pulsators 2 or 3 dedicated small telescopes - next step simultaneous observations of 2 or 3 stars 2-m class telescope? -stellar magnitude < 8.5 for solar-like oscillations - increase of the number of reachable targets possibility to achieve specific observations in selected targets However, a dedicated telescope would be required Catania 09/08 SIAMOIS 27/26 Fourier Transform Seismometry Fourier transform Seismometry: The Doppler signal is retrieved from the interferogram of the stellar spectrum Catania 09/08 SIAMOIS 28/26 Photometry / activity Catania 09/08 SIAMOIS 29/26 Bright targets Solar-like targets with solar-like oscillations [A scaled to (L/M)0.7] - d Scuti Catania 09/08 - g Dor - PMS SIAMOIS - Red giants 30/26 An example Mosser et al 2008 HD 203608, F8V, mV = 4.2 Observations with HARPS: - 5 nights - duty cycle ~ 40 % - SNR = 5 Precision of interior structure parameters improved by a factor 3 to 10 Catania 09/08 SIAMOIS 31/26