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Kaspar von Braun (NASA Exoplanet Science Institute / Caltech) and

The GJ 436 and 55 Cnc Systems: Direct Exoplanetary Diameter and Fundamental Stellar Parameters. Kaspar von Braun (NASA Exoplanet Science Institute / Caltech) and.

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Kaspar von Braun (NASA Exoplanet Science Institute / Caltech) and

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  1. The GJ 436 and 55CncSystems: Direct Exoplanetary Diameter and Fundamental Stellar Parameters Kaspar von Braun (NASA Exoplanet Science Institute / Caltech) and • T. S. Boyajian,S. R. Kane, G. T. van Belle, D. R. Ciardi, M. Lopez-Morales, H. A. McAlister, T. Henry, C. Farrington, P. J. Goldfinger, G. Schaefer, T. A. ten Brummelaar, S. Ridgway, L. Sturmann, J. Sturmann, N. H. Turner

  2. Motivation: Understand the Parent Stars • Insights from Fundamental Stellar Parameters • Host star is primary energy source of the system. • Planetary formation, evolution. • Radiation environment. • Habitable Zone (HZ). • Transiting Planet: directly determined planetary diameter. • Approach (next few slides) • Interferometry: angular stellar diameter. • With trigonometric parallax: physical stellar diameter. • SED fit: stellar bolometric flux. • From angular diameter and FBOL: TEFF and L. • From L, TEFF: habitable zone. • From photometric flux decrement during transit: planetary diameter. K. von Braun -- Corot 2011 Marseile

  3. Methods (stellar radius) • Interferometric Measurements (CHARA) • H-band (1.67 micron) • Longest available baselines (~ 330m) • Distance from trigonometric parallax measurements. Flux ~ R2T4 / d2 ~ θ2T4 K. von Braun -- Corot 2011 Marseile http://www.chara.gsu.edu/CHARA/

  4. Methods (stellar radius) • Interferometric Measurements: 55 Cnc PTI data (van Belle & von Braun 2009) CHARA data K. von Braun -- Corot 2011 Marseile

  5. Methods (stellar temperature) • Literature Photometry and Spectral Templates • Pickles (1998) templates • SEDfit code (A. Boden) • TEFF= f (FBOL, θ) 55 Cnc HZ boundary calculations using Jones & Sleep (2010) HZ ~ f (L, TEFF) K. von Braun -- Corot 2011 Marseile von Braun et al. (2011)

  6. GJ 436 & 55 Cnc: Results • Stellar Parameters Parameter GJ 436 55 Cnc Spectral Type M3 V K0 IV-V θUD(mas) 0.405(13) 0.685(4) θLD(mas) 0.414(13) 0.711(4) FBOL(10-8 erg/s/cm2) 0.788(1) 12.27(2) Radius (solar) 0.452(18) 0.943(10) Luminosity (solar) 0.0257(1) 0.582(14) TEFF(K) 3427(53) 5196(24) HZ boundaries (AU) 0.16—0.31 0.67—1.32 aPlanet(AU) (b) 0.03 (f) 0.78 K. von Braun -- Corot 2011 Marseile

  7. GJ 436b – Transiting Neptune Deming et al. (2007), Stevenson et al. (2010): planet brightness temperature ~ 700-1000 K (mid-IR). Deming et al. (2007), Gillon et al. (2007a,b), Bean et al. (2008), Ballard et al. (2010), Pont et al. (2008), Shporer et al. (2009): non-grazing planet; measure δ(~0.006-0.007). Using our R* and median literature δ, obtain: R (GJ 436b) = (4.09 +- 0.19) Rearth K. von Braun -- Corot 2011 Marseile Winn (2010) For dark planet and non-grazing transit: δ = k = Rp2 / R*2 More details…

  8. 55 Cnc Dawson & Fabrycky (2010) • Habitable Zone K. von Braun -- Corot 2011 Marseile von Braun et al. (2011) Habitable Zone

  9. 55 Cnc • Habitable Zone K. von Braun -- Corot 2011 Marseile von Braun et al. 2011 Habitable Zone Orbital parameters from Dawson & Fabrycky (2010)

  10. 55 Cnc • Transiting Planet K. von Braun -- Corot 2011 Marseile Orbital parameters from Dawson & Fabrycky (2010)

  11. 55 Cnc K. von Braun -- Corot 2011 Marseile von Braun et al. 2011, astro-ph/1106.1152

  12. 55 Cnc K. von Braun -- Corot 2011 Marseile Winn, Matthews et al. 2011 (updated version)

  13. Summary: Understand the Parent Stars • Directly Determined Stellar Parameters: • Angular and Physical Radius • Effective temperature • Luminosity and Habitable Zone Location / Extent • Results / Derived Parameters • Planetary Radii for Transiting Planets • Planetary bulk density (for known planetary mass) • Planet Equilibrium Temperatures (HZ) Provide directly determined characterizations of exoplanets and their environments. K. von Braun -- Corot 2011 Marseile

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