ESA Cosmic Visions: Phase A study for an M Class Mission

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PLATO PLAnetary Transits Oscillations of
stars

• ESA Cosmic Visions Phase A study for an M Class
  Mission
• A next generation exoplanet transit survey
• Don Pollacco (QUB) PLATO-UK
• Suzanne Aigrain, Martin Barstow,
• Matt Burleigh, Andrew Norton, Ian Roxburgh, Alan
  Smith, Giovanna Tinetti,
• Peter Wheatley, Nic Walton

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Science Objectives
The evolution of exoplanetary systems
comparative exoplanetology

• The evolution of planets and that of their stars
  are intimately linked.
• A complete and precise characterisation of host
  stars is necessary to measure exoplanet
  properties mass, radius, age
• Compare planetary systems of various ages
• Observe exoplanets at different stages of
  dynamical evolution and at different stages of
  physical and chemical evolution
• Correlation of planet evolution with that of
  their hosts stars

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Mission Objectives

• The Search for, and characterisation of,
  exoplanets and their host stars
• logical step forward after CoRoT and Kepler (and
  TESS?)
• Search for exoplanetary transits and
  asteroseismology for the same star samples

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Current/Planned Transit Missions

• CoRoT, flying now, 27cm aperture, 2.5 yr
  duration, 4 deg2, 12000 stars, 2x150d 2x20d
• TESS, Phase A SMEX, multiple small aperture,
  bright stars, Plt60d
• Kepler, launch 2009, 0.95m aperture, 105 deg2, 4
  yr duration, 100000 stars 9-14 mag

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Transit Light curves
Mostly geometry - get radius of planet/star,
inclination of orbit. For a jupiter sized body
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Need the mass, radius and age of the host
seismic analysis

• Radius from Gaia L4?R2?T4
• (will be confirmed by seismology)
• Mass from seismic analysis ??(r), and is model
  independent
• Evolution ? He metals
• but is model dependent
• But final uncertainty on age is small, lt10

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PLATO Target Methodology 1

• The bright stars - 100000 stars with mv lt11
• 1. Space photometry
• - detection/characterisation of exoplanets
• - seismic analysis for mass, radius, age,
  internal structure, angular momentum
• - exoplanet atmospheres (JWST)
• 2. Ground-based follow-up
• - elimination of mimics
• - exoplanet mass determination
• - host chemical composition
• - exoplanet imaging (brightest/nearest) (ELT)

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PLATO Target Methodology 2

• Fainter stars - 400000 stars
• - complete characterisation of exoplanets (size,
  mass, age)
• - correlation of planetary verses stellar
  evolution
• - improvement of exoplanet statistics
• Complete and unbiased database to understand the
  evolution of stars and planets

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Main Requirements

• 1. Science
• - photometry of gt100000 stars, mvlt11, noise
  lt2.5x10-5 in 1hr
• - photometry of gt400000 stars, mvlt13-14, noise
  lt8.0x10-5 in 1hr
• - photometry of 1000 stars, mvgt4
• - long duration monitoring gt 3 years
• - duty cycle gt 95
• 2. Instrument
• - very wide field gt550 deg2
• - successive fields (3yr 2yr) step and
  stare phase (1yr 4x3months)
• - large collecting area
• - sampling time 30 sec or 10 min
• - pointing stability lt 0.2 arcsec
• - low non-photonic noise (1/3 photon at mv11)

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Plato - ESA Study group conclusion slide
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Baseline design 1

• 28 telescopes with 10cm pupil
• Focal plane of each 4x CCD 3854x3854 x18m
• Fov 557 deg2
• All telescopes observe same field
• - 26 identical 30 sec cadence, white light,
  mv8-14
• - 2 specific 1 sec, frame transfer
  architecture, 2 broadband filters, mv4-8
• L2 orbit

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Baseline Design 2
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Baseline Design 3
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Baseline Design 4
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Baseline Design 5
Detector Characteristics

• 150 CCDs to be procured!

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PLATO Performance 1
Fov gt550 deg2 4
100
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PLATO Performance 2
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The PLATO Consortium

• Structures are evolving extremely quickly - so
  get involved soon!
• Payload PI - Claude Catala (Paris)
• Science PI - tbd (30th Sept)

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The Cosmic Visions timeline