1. PLAnetary Transits and Oscillations of stars H. Rauer 1, C. Catala 2, D. Pollacco 3, S. Udry 4 and the PLATO Team 1: Institut für Planetenforschung, DLR and TU Berlin 2: Observatoire de Paris, LESIA 3: Univ. Belfast 4: Obs. Geneva http://www.oact.inaf.it/plato/PPLC/Home.html M-class mission candidate in ESA Cosmic Vision Program; In competition for launch in 2018

2. PLATO Science Objective > measurement of radius and mass, hence of planet mean density > measurement of age of host stars, hence of planetary systems

3. Transits: Planetary Parameters Key Tool Mostly geometry radius of planet/star, inclination. Keplers 3 rd law => semi-major axis Only needed physics: limb darkening Sun + Jupiter : ~ 1% dip Sun + Earth : ~ 0.01% dip

4. CoRoT 7b Kepler 4b GJ1214b GJ436b Detection range of transit surveys Space surveys Ground- based surveys TrES-4b HAT-P-7b HD149026b CoRoT-2b HAT-P-12b HAT-P-11b

5. PLATO Survey of 1R E rocky planets in habitable zones of all late type stars News: Now includes M dwarfs M stars lower intrinsic brightness (local) and very red PLATO can work as faint as I~15-16 mag with little blending in most cases 6000 M stars per pointing RV signal larger

6. Groundbased follow-up - Vigorous follow-up needed - Most important aspect = radial velocity monitoring planet confirmation and mass measurement PlanetDistance (AU) RV Amp. (m/s) Jupiter128.4 Neptune0.14.8 Neptune11.5 SuperEarth0.11.4 SuperEarth10.5 Earth10.1 - stellar intrinsic « noise »: oscillations, granulation, activity - need to apply proper averaging technique - time consuming - in practice limited to bright stars PLATO CoRoT - Kepler telescope diameter needed to confirm earth-like planet

7. Asteroseismology Key Tool Planet parameters stellar parameters (asteroseismology) Solar-like stars oscillate in many modes, excited by convection. Sound waves trapped in interior Resonant frequencies determined by structure: frequencies probe structure gives mass, angular momentum, age

8. Power spectrum of light curve gives frequencies Asteroseismology Inversions + model fitting + consistent, M,, J, age PLATO will provide: Large separations M/R 3 mean density Small separations d 02 probe the core age Uncertainty in Age ~ 10% Uncertainty in Mass ~ 2% CoRoT 1.36 +/- 0.04 M 3.90 +/- 0.4 Gyr

9. 8.0 x 10 -5 in 1 hr for marginal transit detection 1 R planet transiting a solar-like star at 1 AU - mean of 3 transits Noise level requirements for PLATO 2.7 x 10 -5 in 1 hr for high S/N transit measurement: also required for seismic analysis

10. The PLATO star samples m V 11 m <11 2.7 10 -5 / hr 20,000 cool dwarfs & subgiants m V 10-11.5 m V 8 1,000 / 3,000 cool dwarfs & subgiants 11 < m V 13 8.0 10 -5 / hr 250,000 cool dwarfs & subgiants

11. Instrumental Concept - 32 « normal » cameras : cadence 25 sec - 2 « fast » cameras : cadence 2.5 sec - pupil 120 mm - dynamical range: 4 m V 16 Very wide field + large collecting area : multi-instrument approach on board data treatment: 1 DPU per camera 1 ICU optical field 37° 4 CCDs: 4510 2 18 m « normal » « fast » focal planes FPA 356 mm S-FPL51 N-KzFS11 CaF2 (Lithotec) S-FPL53 L-PHL1 KzFSN5 164.6 mm optics fully dioptric, 6 lenses Orbit around L2 Lagrangian point, 6-year nominal lifetime

12. Concept of overlapping line of sights 4 groups of 8 cameras with offset lines of sight offset = 0.35 x field diameter 8 8 8 8 16 24 32 Optimization of number of stars at given noise level AND of number of stars at given magnitude 37° 50°

13. Kepler CoRoT Basic observation strategy Observation strategy: 1. two long pointings : 3 years or 2 years 2. « step&stare » phase (1 or 2 years) : N fields 2-5 months each

14. PLATO Kepler CoRoT > 40% of the whole sky ! Basic observation strategy Observation strategy: 1. two long pointings : 3 years or 2 years 2. « step&stare » phase (1 or 2 years) : N fields 2-5 months each

15. Assumptions: - each star has one and only one planet in each cell - planet is detected if a transit signal AND a radial velocity signal are measured - intrinsic stellar « noise » is taken into account Expected number of confirmed planets lower right corner of the (orbit,mass) plane = terrestrial planets in the HZ, not covered by Kepler, will be explored by PLATO thanks to its priority on bright stars

16. - Wagner et al. 2009, also: Valencia et al. 2007 standard error bar Compare exoplanets with predictions of models with various compositions and structures error bar dominated by error of host stars characteristics Impact of radius and mass measurement

17. - Wagner et al. 2009, also: Valencia et al. 2007 5% 10% 5% maximum acceptable error bars standard error bar Compare exoplanets with predictions of models with various compositions and structures Impact of radius and mass measurement error bar dominated by error of host stars characteristics

18. - constraints on planet interiors - radii and masses atmospheres - diversity - Wagner et al. 2009, also: Valencia et al. 2007 5% 10% 5% maximum acceptable error bars PLATO error bar standard error bar Compare exoplanets with predictions of models with various compositions and structures Impact of radius and mass measurement

19. PLATO: compare Earth-like exoplanets with age scale of Earth - precision better than timescale planet evolution - targets of future characterization dated by PLATO (Earth-like, but also Neptunes, hot Jupiters…) Impact of age measurement place exoplanetary systems in evolutionary context Magnetosphere Carbon-silicate cycle Oxygen rise Ozone layer Proto Earth

20. Objective : Detect and characterize planetary systems, particularly earth-like in habitable zone Techniques: detection by transits + asteroseismology of host stars + ground based spectroscopy Instrument: Multi-telescopes very wide field of view Targets: > 20,000 bright cool dwarfs (noise < 2.7 10 -5 in one hr) > 50,000 bright cool dwarfs (m v <11) > 6,000 very nearby M dwarfs > 230,000 cool dwarfs (m v <13,noise < 8.0 10 -5 in one hr ) Observing strategy: 2 long runs (2-3 years) + several short runs PLATO: Summary More than 40% sky coverage