The Detectability of Habitable Exomoons David Kipping Steve
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? 2/20 Pathways 2009, D. Kipping
Critical Questions • Do extrasolar planets host moons? • How do moons and planets form? 2/20 Pathways 2009, D. Kipping
Critical Questions • Do extrasolar planets host moons? • How do moons and planets form? • Does complex planetary life require a moon? 2/20 Pathways 2009, D. Kipping
Critical Questions • • 2/20 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
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-Mc. Claughlin effect distortions (Simon et al. 2009, poster: Szabo et al. ) 2/20 Pathways 2009, D. Kipping
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry 2/20 Pathways 2009, D. Kipping
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry 2/20 Pathways 2009, D. Kipping
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry 2/20 Pathways 2009, D. Kipping
Transit timing variations (TTV) • Planet-moon orbit a common centre-of-gravity • TTV is akin to astrometry 2/20 Pathways 2009, D. Kipping
Transit timing variations (TTV) • • 2/20 A few problems. . . Lots of things can cause TTV frequency > Nyquist frequency => harmonics TTV amplitude ~ mass*distance Pathways 2009, D. Kipping
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity 2/20 Pathways 2009, D. Kipping
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity 2/20 Pathways 2009, D. Kipping
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity 2/20 Pathways 2009, D. Kipping
Transit duration variations (TDV) • TTV is a positional effect, like astrometry • TDV is a velocity effect, like radial velocity 2/20 Pathways 2009, D. Kipping
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 2/20 Pathways 2009, D. Kipping
Kepler-class photometry • Kepler is the most precise photometer currently available: 20 ppm/hour • But the ground is catching up fast! • RISE instrument, Liverpool Telescope: 60 ppm/hour 2/20 Pathways 2009, D. Kipping
Detectability with Kepler 1. Accurately model the noise 2/20 Pathways 2009, D. Kipping
Detectability with Kepler 2. Calculate timing and duration uncertainties Carter et al. (2009) – one of the most useful papers! 2/20 Pathways 2009, D. Kipping
Detectability with Kepler 2. Calculate timing and duration uncertainties Carter et al. (2009) – one of the most useful papers! 2/20 Pathways 2009, D. Kipping
Detectability with Kepler 2. Calculate timing and duration uncertainties Carter et al. (2009) – one of the most useful papers! 2/20 Pathways 2009, D. Kipping
Detectability with Kepler 3. Estimate TTV and TDV amplitudes Kipping et al. (2009 a) and (2009 b) 2/20 Pathways 2009, D. Kipping
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) 2/20 Pathways 2009, D. Kipping
Results 1) Low-density planets offer largest SNR 2/20 Pathways 2009, D. Kipping
Results 2. Habitable moons down to 0. 2 Earth masses are detectable 2/20 Pathways 2009, D. Kipping
Results 3. Around 25, 000 stars could be surveyed for habitablezone exomoons with Kepler-class photometry Pathways 2009, D. Kipping
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