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Characterising exoplanetary systems with space-based Bracewell interferometers

Characterising exoplanetary systems with space-based Bracewell interferometers. ARC meeting Denis Defrère. Liege, 19 February 2009. Motivations. Probing the inner region of planetary systems Observationnal constraints : - high angular resolution

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Characterising exoplanetary systems with space-based Bracewell interferometers

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  1. Characterising exoplanetary systems with space-based Bracewell interferometers ARC meeting Denis Defrère Liege, 19 February 2009

  2. Motivations • Probing the innerregion of planetarysystems • Observationnalconstraints: • - highangularresolution • - highdynamic (1/106 to 1/1010) ? Exozodiacal discs Extrasolarplanets • Signal: formation, evolution and architecture of planetarysystems • Noise: level of exozodiacaldustaroundnearby MS stars

  3. Motivations • 1-zodi disc 300 times brighterthanEarth • Implications for life-findingnullinginterferometry missions:

  4. Pegase/FKSI space-based precursors to Darwin/TPF

  5. Mission overview • Pegase • Proposed in 2004 to CNES • Free-flyingdemonstrator • FKSI (Fourier-Kelvin StellarInterfer.) • GSFC mission (NASA) • Studiedat the phase A level

  6. Mission overview

  7. Mission overview • Common science objectives: • Spectroscopy of hot extrasolargiantplanets • Circumstellar discs • Brown dwarfs • Active galacticnuclei

  8. Detection principle Subtracting starlight by destructive interference

  9. Performance for exozodiacal disc detection

  10. Performance for disc detection . • Adapting the GENIEsim software for space-based nulling interferometers • Detectable exozodiacal density for 4 representative Darwin targets • FKSI more sensitive in all cases

  11. Comparison with ground-based sites

  12. Comparison with ground-based sites • Space-based instruments outperform GENIE and ALADDIN: • Pegase: by a factor 2 to 15; • FKSI: by a factor 25 to 50. • Main advantages: • Low thermal background; • Good OPD control.

  13. Prospects for Super-Earth detection

  14. “Super-Earth” extrasolar planets • Main characteristics: • Between 2 and 10 Earth masses • 14 detected so far by radial velocity, microlensing or pulsar timing: • around low-mass stars • semi-major axes range between 0.02 and 2 au • Foundlikely in multiplanetarysystems (80% known candidates) • Favorable examples:

  15. Detection of know Super-Earths • FKSI not well suited for known Super-Earths (baseline too short)

  16. Detection of know Super-Earths

  17. Detection sensitivity • FKSI not convenient for Super-Earths • Could detect Neptune-sized planets (SNR increases as Rp²)

  18. Sky coverage GENIE: 80% ALADDIN: 35% PEGASE: 50% FKSI: 30% • 1354 target star in the Darwin/TPF catalogue • ALADDIN and space-based instruments complementary

  19. Summary and conclusions • Performance study for exozodiacal disc detection • Space-based instruments far more sensitive • Detection achieve very quickly • FKSI: 1-zodi level achievable for all Darwin/TPF targets • Pegase: shorter baseline configuration highly recommended • Prospects for Super-Earth exoplanet detection • FKSI not convenient to observe Super-Earth exoplanets • Can do the job for some short period Super-Earths • Sky coverage complementary with ALADDIN

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