Precise Stellar Parameters are Crucial for Constraining Transiting Exoplanet Interiors

Transcription

1 Precise Stellar Parameters are Crucial for Constraining Transiting Exoplanet Interiors Andrew Vanderburg! NASA Sagan Fellow The University of Texas at Austin Juliette C. Becker, Lars A. Buchhave, Annelies Mortier, Eric Lopez, Luca Malavolta, Raphaëlle D. Haywood, David W. Latham, David Charbonneau, Mercedes Lopez-Morales, Christophe Lovis, Alessandro Sozzetti, Francesco Pepe, Andrew Collier Cameron, Xavier Dumusque, Emilio Molinari, Stephane Udry, Fred C. Adams, Aldo Bonomo, Rosario Cosentino, Luca Di Fabrizio, Aldo Fiorenzano, Avet Harutyunyan, Vania Lorenzi, Marco Pedani, Francois Bouchy, John Asher Johnson, Michel Mayor, Giusi Micela, Giampaolo Piotto, David Phillips, Ken Rice, Dimitar Sasselov, Damien Segransan, Chris Watson Know Thy Star Conference, October 9, 2017

2 Gravitationally differentiated bodies have layers of different materials Image: NASA

3 Gravitationally differentiated bodies have layers of different materials Neptune Image: NASA

4 We infer the interior structures of exoplanets from mass and radius Curves from Zeng et al. (2015) and Seager et al. (2007)

5 We infer the interior structures of exoplanets from mass and radius Curves from Zeng et al. (2015) and Seager et al. (2007) Two Direct Observables: mass & radius! Four Variables: core (iron) fraction, mantle (silicate) faction, dense volatile (ice) fraction, H2 fraction!

6 We infer the interior structures of exoplanets from mass and radius Curves from Zeng et al. (2015) and Seager et al. (2007)

7 We infer the interior structures of exoplanets from mass and radius Curves from Zeng et al. (2015) and Seager et al. (2007)

8 For strong interior structure constraints, we need: Precise Rp/R Precise RV semiamplitude: Precise stellar parameters, especially R :

9 Case Study: WASP Re, 0.79 day period 13 Re, 4.16 day period 3.6 Re, 9.03 day period Becker, Vanderburg+ 2015

10 WASP-47 c 1.8 Re, 0.79 day period 13 Re, 4.16 day period 3.6 Re, 9.03 day period Neveu-VanMalle+ Becker, Vanderburg+ 2015

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12 10 5 WASP-47 e P = 0.79d WASP-47 b P = 4.16d Radial Velocity, m s WASP-47 d P = 9.03d WASP-47 c P = 588d Orbital Phase HARPS-N HIRES PFS CORALIE Vanderburg+2017 Including archival" data from" Neveu-VanMalle 2015," Dai+2015," Sinukoff+2016

13 WASP-47 is a good system for interior structure constraints Precise Rp/R : limb darkening, impact parameter, transit depth, short cadence data. Precise RV semiamplitude: Lots of precise RVs, good sampling/phase coverage,understanding of stellar activity Precise stellar parameters, especially R : Asteroseismology, measured stellar density, eclipsing binary/circumbinary planets, solar twin, etc.

14 The known hot Jupiter, planet e s short period, old quiet sun-like host star, and bright V-band magnitude contribute to: Precise Rp/R : limb darkening, impact parameter, transit depth, short cadence data. Precise RV semiamplitude: Lots of precise RVs, good sampling/phase coverage, understanding of stellar activity Precise stellar parameters, especially R : Asteroseismology, measured stellar density, eclipsing binary/circumbinary planets, solar twin, etc.

15 The known hot Jupiter, planet e s short period, old quiet sun-like host star, and bright V-band magnitude contribute to: Precise Rp/R : limb darkening, impact parameter, transit depth, short cadence data. Precise RV semiamplitude: Lots of precise RVs, good sampling/phase coverage, understanding of stellar activity 0.5% and 0.8% Rp/R " for planets d and e 10.9% and 9.5% K " for planets d and e Precise stellar parameters, especially R : Asteroseismology, measured stellar density, 3% and 1% " eclipsing binary/circumbinary planets, solar twin, etc. for M and R

16 Vanderburg+2017 WASP-47 e does not have an Earth-like core

17 In the TESS era: Precise Rp/R : limb darkening, impact parameter, transit depth, short cadence data. Precise RV semiamplitude: Lots of precise RVs, good sampling/phase coverage, understanding of stellar activity Precise stellar parameters, especially R : Asteroseismology, measured stellar density, eclipsing binary/circumbinary planets, solar twin, etc.

18 Advantages of TESS over Kepler: Precise Rp/R : limb darkening, impact parameter, transit depth, short cadence data. Precise RV semiamplitude: Lots of precise RVs, good sampling/phase coverage, understanding of stellar activity" Precise stellar parameters, especially R : Asteroseismology, measured stellar density, eclipsing binary/circumbinary planets, solar twin, etc.

19 Disadvantages of TESS over Kepler: Precise Rp/R : limb darkening, impact parameter, transit depth, short cadence data. Precise RV semiamplitude: Lots of precise RVs, good sampling/phase coverage, understanding of stellar activity Precise stellar parameters, especially R : Asteroseismology, measured stellar density, eclipsing binary/circumbinary planets, solar twins, etc.

20 With stellar density prior Vanderburg+2017

21 Without stellar density prior Vanderburg+2017

22 Asteroseismology will be! relatively rare for planet! hosts - Campante Image: NASA/JPL-Caltech The size of the exoplanet, dubbed Kepler-93 b, is now known to an uncertainty of just 74 miles (119 kilometers) on either side of the planetary body. NASA Press Release

23 Asteroseismology will be! relatively rare for planet! hosts - Campante Image: NASA/JPL-Caltech We have been spoiled by Kepler Dave Latham

24 Other constraints on stellar parameters? Scott+2013 Image: ESA

25 Summary Constraining the interior structure of a rocky exoplanet requires very precise stellar parameters, especially for the stellar radius. " WASP-47 e is less dense than an Earth-like core/ mantle composition, and therefore likely has an envelope of heavy volatile elements like water. " For the TESS era, we should be strategic how we choose planets to follow up with RVs. Prioritize targets where precise Rp/R s and stellar radii are possible, and stop observing when the planet mass uncertainty is about 3.6 times larger than the radius uncertainty.

26 Exoplanet Interior Structures in the Kepler Era 2.5 Marcus Zeng + Sasselov 2013 This Paper GJ 1214b HD97658b K10c Planet Radius (R Earth ) % H2O 25% MgSiO3 75% H2O 50% MgSiO3 50% H2O K10b CoRoT-7b K93b K36b 55Cnc e HIP b 100% MgSiO3 50% Fe 50% MgSiO3 100% Fe 1.0 Earth Venus K78b Planet Mass (M Earth )