PLA netary T ransits and O scillations of stars

1. PLAnetary Transits and Oscillations of stars http://www.oact.inaf.it/plato/PPLC/Home.html H. Rauer1, C. Catala2, D. Pollacco3, S. Udry4 and the PLATO Team 1: Institut für Planetenforschung, DLR and TU Berlin 2: Observatoire de Paris, LESIA 3: Univ. Belfast 4: Obs. Geneva 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. • Kepler’s 3rd law => semi-major axis Only needed physics: limb darkening Sun + Jupiter : ~ 1% dip Sun + Earth : ~ 0.01% dip

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

5. PLATO Survey of 1RE 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 CoRoT - Kepler telescope diameter needed to confirm earth-like planet • stellar intrinsic « noise »: • oscillations, granulation, activity • need to apply proper averaging technique • time consuming • in practice limited to bright stars PLATO

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. Asteroseismology Power spectrum of light curve gives frequencies n Large separations M/R3 mean density Small separations d02  probe the core  age CoRoT 1.36 +/- 0.04 M 3.90 +/- 0.4 Gyr Inversions + model fitting + n consistent , M, , J, age PLATO will provide: Uncertainty in Mass ~ 2% Uncertainty in Age ~ 10%

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

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

11. Instrumental Concept optics 356 mm S-FPL51 L-PHL1 N-KzFS11 CaF2 (Lithotec) S-FPL53 KzFSN5 164.6 mm FPA focal planes optical field 37° 4 CCDs: 45102 18m « normal » « fast » on board data treatment: 1 DPU per camera 1 ICU Very wide field + large collecting area : multi-instrument approach fully dioptric, 6 lenses • - 32 « normal » cameras : cadence 25 sec • 2 « fast » cameras : cadence 2.5 sec • pupil 120 mm • - dynamical range: 4 ≤ mV ≤ 16 Orbit around L2 Lagrangian point, 6-year nominal lifetime

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

13. 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 Kepler CoRoT CoRoT

14. 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 >40% of the whole sky ! Kepler PLATO CoRoT CoRoT PLATO

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

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

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

19. Proto Earth Magnetosphere Carbon-silicate cycle Oxygen rise Ozone layer Impact of age measurement 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…) place exoplanetary systems in evolutionary context

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