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The Detectability of Habitable Exomoons. David Kipping, Steve Fossey , Giammarco Campanella. Collaborators: Giovanna Tinetti , Alan Aylward , Ignasi Ribas , Jean-Philippe Beaulieu, Steve Fossey , the HOLMES collaborationc. Critical Questions. Do extrasolar planets host moons?.
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The Detectability of Habitable Exomoons David Kipping, Steve Fossey, GiammarcoCampanella Collaborators: Giovanna Tinetti, Alan Aylward, IgnasiRibas, Jean-Philippe Beaulieu, Steve Fossey, the HOLMES collaborationc
Critical Questions • Do extrasolar planets host moons? Pathways 2009, D. Kipping 2/20
Critical Questions • Do extrasolar planets host moons? • How do moons and planets form? Pathways 2009, D. Kipping 2/20
Critical Questions • Do extrasolar planets host moons? • How do moons and planets form? • Does complex planetary life require a moon? Pathways 2009, D. Kipping 2/20
Critical Questions • Do extrasolar planets host moons? • How do moons and planets form? • Does complex planetary life require a moon? • Can moons host life? Pathways 2009, D. Kipping 2/20
How to detect an exomoon • Highly challenging! • Transit timing variations (Sartoretti & Schneider 1999) • Microlensing (Han et al. 2002) • Planet-moon eclipses (Cabrera & Schneider 2002) • Lightcurve distortions (Simon et al. 2007) • Pulsar timing (Lewis et al. 2008) • Transit duration variations (Kipping 2009) • Rossiter-McClaughlin effect distortions (Simon et al. 2009, poster: Szabo et al.) Pathways 2009, D. Kipping 2/20
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry Pathways 2009, D. Kipping 2/20
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry Pathways 2009, D. Kipping 2/20
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry Pathways 2009, D. Kipping 2/20
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry Pathways 2009, D. Kipping 2/20
Transit timing variations (TTV) • A few problems... • Lots of things can cause TTV • TTV frequency > Nyquist frequency => harmonics • TTV amplitude ~ mass*distance Pathways 2009, D. Kipping 2/20
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity Pathways 2009, D. Kipping 2/20
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity Pathways 2009, D. Kipping 2/20
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity Pathways 2009, D. Kipping 2/20
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity Pathways 2009, D. Kipping 2/20
Transit duration variations (TDV) • BENEFITS • TTV and TDV are 90 degrees out-of-phase • TDV amplitude ~ mass/SQRT(distance) • Ratio of amplitudes gives period (distance) and mass • Correlated noise expected to create 180 degree phase shift • Additional diagnostic – may compare to harmonic frequencies Pathways 2009, D. Kipping 2/20
Kepler-class photometry • Kepler is the most precise photometer currently available: 20ppm/hour • But the ground is catching up fast! • RISE instrument, Liverpool Telescope: 60ppm/hour Pathways 2009, D. Kipping 2/20
Detectability with Kepler • 1. Accurately model the noise Pathways 2009, D. Kipping 2/20
Detectability with Kepler • 2. Calculate timing and duration uncertainties • Carter et al. (2009) – one of the most useful papers! Pathways 2009, D. Kipping 2/20
Detectability with Kepler • 2. Calculate timing and duration uncertainties • Carter et al. (2009) – one of the most useful papers! Pathways 2009, D. Kipping 2/20
Detectability with Kepler • 2. Calculate timing and duration uncertainties • Carter et al. (2009) – one of the most useful papers! Pathways 2009, D. Kipping 2/20
Detectability with Kepler • 3. Estimate TTV and TDV amplitudes • Kipping et al. • (2009a) and • (2009b) Pathways 2009, D. Kipping 2/20
Detectability with Kepler • 4. Compute SNR for range of planet-moon-star systems with a range of visual magnitudes • Need to detect both timing signals to 8-sigmas and 3-sigmas • Period fixed to habitable period • Assume inclination ~ 90 degrees • In each case, planet-moon-star system must be dynamically stable for 5 Gyr (Barnes & O’Brien 2002) Pathways 2009, D. Kipping 2/20
Results • 1) Low-density planets offer largest SNR Pathways 2009, D. Kipping 2/20
Results • 2. Habitable moons down to 0.2 Earth masses are detectable Pathways 2009, D. Kipping 2/20
Results • 3. Around 25,000 stars could be surveyed for habitable-zone exomoons with Kepler-class photometry Pathways 2009, D. Kipping