SEARCHING FOR PLANETS IN THE HABITABLE ZONE. FROM COROT TO PLATO
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Transcript of SEARCHING FOR PLANETS IN THE HABITABLE ZONE. FROM COROT TO PLATO
SEARCHING FOR PLANETS IN THE HABITABLE ZONE.
FROM COROT TO PLATO
Ennio Poretti – INAF OAB
51 Pegasi :Discovered by Mayor & Queloz(1995, Nature 378, 355)
The first extrasolar planet
Wolszczan & Frail, 1992, Nature 355, 145
RADIAL VELOCITY
635 detections
TIMING METHOD:periodic deviations from a given
ephemeris.
The case of the pulsar PSR1257+12
(10 detections)
MICROLENSING
(12 detections)
ASTROMETRY (waiting for GAIA, used in KEPLER data)
Fomalhaut b : Hubble images taken 2 years apart (Kalas et al.2008)
DIRECT IMAGING (15 detections)
THE TRANSIT METHOD
Planetary massDensity
InclinationOrbital distancePlanetary radius
Using Doppler data too:
Angle between orbital plane and equatorial plane(Rossiter effect)
INFRARED:
EllipticityPhotons from planet
Spectroscopy during the transit:
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CCD A1 CCD E1
CCD E2CCD A2
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3.05°
2.70°
AsteroseismologyBright stars 5.5 < V < 9.52x5 in each field
Exoplanetary searchFaint stars 11.0 < V < 16.52x6000 in each field
Mission life extended to 20125 long runs (150 d each or 2x80d)10 short runs (20 - 30 d)
V = 6 --> ~2.5 104 photons cm-2 s –1
outside atmosphere , T ~ 6000°Kmv = 16 --> ~2.5 photons cm-2 s -1
CoRoTCoRoT
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SummerZone of observationcentered at 18h50
WinterZone of observationcentered at 6h50
Galaxy
COROT, 30 cm mirrorV> 12 , raw data
CoRoT 1b
HUBBLE, 2.5m mirror,V=7.8, published curve
HD 209458
RESULTS
Mandel & Agol formalism
Limb-darkening quadratic law(Claret)
Using RS = 1.11±0.05 R
RP/RS= 0.1350±0.0018 RP = 1.46±0.07 RG
RP = 1.45±0.07 RG
RP = 1.44±0.07 RG
RP/RS= 0.1349±0.0015RP/RS= 0.1332±0.0008
RP/RS= 0.1334±0.0016a/RS= 4.89±0.06
sin i = 0.996±0.001tc= 2593.3263±0.0008
White light curve
Coloured light curves
COROT 1bLaurea ThesisFrancesco Borsa
CoRoT 3b: the link between stars and planets
Different depths of
the transit
RS = 1.56±0.09 R
RP = 0.78±0.07 RG
RP = 0.78±0.07 RG
RP = 0.98±0.06 RG
Stellar object !!
RP/RS= 0.0608±0.0006a/RS= 7.90±0.18
sin i= 0.998±0.001tc= 2695.5700±0.0012
P = 4.25695±0.00009d
M = 21.7±1 MJ
Deuterium burning
Laurea Thesis Francesco Borsa
LINE PROFILE VARIATIONS BY USING HARPS The fingerprint of the nonradial pulsations
V1127 Aql: the full Blazhko effect
Line profile variations allow us :-To separate radial modes from nonradial modes-To broke the degeneracy in m due to the rotational splitting
Mean line profile (top) and standarddeviation across the line profile(in red after removing 20 frequencies)
HD 50870
MODE IDENTIFICATION HD 50844 (l,m couples)
Inclination angle: 82°
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Power spectrum of light curve gives frequencies
Asteroseismology
Inversions + model fitting + consistent , M, , J, age:
Large separations M/R3 densitySmall separations d02
probe the core age
Uncertainty in Age ~ 10%
Uncertainty in Mass ~ 2%
Asteroseismic age of the Sun: 4.68 +/- 0.02 Gys (Houdek & Gough, 2007)
N. Batalha et al. [2011 Jan 10]
N. Batalha, et al. [2010 Jan 11]
Jupiter, Saturn, Uranus, Neptune and icy-rocky trans-neptunian bodies
Interaction between giant planets and external bodies. Increase of the angular moments of the giant planets.
INSTABILITY: Jupiter and Saturn in 2:1 resonance. Giant planets shifted outward
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PLATOPLAnetary Transits and Oscillations of Stars
The exoplanetary system explorer
Main objective: - detect and characterize exoplanets of all kinds around stars of all
types and all ages full statistical study of formation and evolution of
exoplanetary systems- including telluric planets in the habitable zone of their host stars
Three complementary techniques:- photometric transits : Rp/Rs (Rs known thanks to Gaia)
- groundbased follow-up in radial velocity : Mp/Ms
- seismic analysis of host-stars (stellar oscillations) : Rs, Ms, age
> measurement of radius and mass, hence of planet mean density
> measurement of age of host stars, hence of planetary systems
Tool:- ultra-high precision, long, uninterrupted, CCD photometric monitoring of very
large samples of bright stars: CoRoT - Kepler heritage
- bright stars: efficient groundbased follow-up and capability of seismic analysis
PLATO Science Objectives
Instrumental Concept
- 32 « normal » cameras : cadence 25 sec- 2 « fast » cameras : cadence 2.5 sec, 2 colours- pupil 120 mm- dynamical range: 4 ≤ mV ≤ 16
optical field 37°
4 CCDs: 45102 18m
« normal » « fast »
focal planes
fully dioptric, 6 lenses + 1 window
Very wide field + large collecting area :multi-instrument approach
optical design
On board data treatment: 1 DPU /2 cameras + 1 ICU Science ground segment
Orbit around L2 Lagrangian point, 6+2 year lifetime
Concept of overlapping line of sight
4 groups of 8 cameras with offset lines of sightoffset = 0.35 x field diameter
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Optimization of number of stars at given noise level AND of number of stars at given magnitude
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CoRoT CoRoT
KeplerPLATO
PLATO
Basic observation strategy
very wide field + 2 successive long monitoring phases:
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KeplerPLATO
PLATO
25% of the whole sky !
CoRoT CoRoT
step and stare phase (1 year) : N fields for 3-5 months each- increase sky coverage - potential to re-visit interesting targets
- explore various stellar environments
Basic observation strategy
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PLATO
PLATO
Kepler
CoRoT CoRoT
step and stare phase (2 years) : N fields for 3-5 months each- increase sky coverage - potential to re-visit interesting targets
- explore various stellar environments
42% of the whole sky !
Basic observation strategy
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The Discovery Space
Transit RV μlensing
PLATO
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Planet population predictions
Small planets expected to be very common andPLATO could monitor the 42% of the sky !
Observations Population
Synthesis?
monitor in ultra-high precision photometry
a very large number
of bright and very bright stars
The PLATO challenge
CoRoT
Plato (2018)
Kepler
THE FUTURE OF ASTEROSEISMOLOGY AND SEARCH OF “EARTHS”
E-ELT (2017)
Combination of different techniques, from ground and space
Spectroscopy
Photometry
HARPS, HARPS-N ESPRESSO, CODEX