T HE GJ 436 AND 55 C NC S YSTEMS : D IRECT E XOPLANETARY D IAMETER AND F UNDAMENTAL S TELLAR P ARAMETERS 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

M OTIVATION : U NDERSTAND THE P ARENT S TARS 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 F BOL : T EFF and L. From L, T EFF : habitable zone. From photometric flux decrement during transit: planetary diameter. 14 June 2011 K. von Braun -- Corot 2011 Marseile 2

M ETHODS ( STELLAR RADIUS ) Interferometric Measurements (CHARA) H -band (1.67 micron) Longest available baselines (~ 330m) Distance from trigonometric parallax measurements. 14 June 2011 K. von Braun -- Corot 2011 Marseile 3 Flux ~ R 2 T 4 / d 2 ~ θ 2 T 4

M ETHODS ( STELLAR RADIUS ) Interferometric Measurements: 55 Cnc 14 June 2011 K. von Braun -- Corot 2011 Marseile 4 PTI data (van Belle & von Braun 2009) CHARA data

M ETHODS ( STELLAR TEMPERATURE ) Literature Photometry and Spectral Templates Pickles (1998) templates SEDfit code (A. Boden) T EFF = f (F BOL, θ) 14 June 2011 K. von Braun -- Corot 2011 Marseile 5 HZ boundary calculations using Jones & Sleep (2010) HZ ~ f (L, T EFF ) 55 Cnc von Braun et al. (2011)

GJ 436 & 55 C NC : R ESULTS Stellar Parameters ParameterGJ Cnc Spectral TypeM3 VK0 IV-V θ UD (mas)0.405(13)0.685(4) θ LD (mas)0.414(13)0.711(4) F BOL (10 -8 erg/s/cm 2 )0.788(1)12.27(2) Radius (solar)0.452(18)0.943(10) Luminosity (solar)0.0257(1)0.582(14) T EFF (K)3427(53)5196(24) HZ boundaries (AU)0.16— —1.32 a Planet (AU)(b) 0.03(f) June 2011 K. von Braun -- Corot 2011 Marseile 6

14 June K. von Braun -- Corot 2011 Marseile For dark planet and non-grazing transit: δ = k = R p 2 / R * 2 GJ 436 B – T RANSITING N EPTUNE Winn (2010) 1.Deming et al. (2007), Stevenson et al. (2010): planet brightness temperature ~ K (mid-IR). 2.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(~ ). 3.Using our R * and median literature δ, obtain: More details… R (GJ 436b) = ( ) R earth

55 C NC Habitable Zone 14 June 2011 K. von Braun -- Corot 2011 Marseile 8 Dawson & Fabrycky (2010) Habitable Zone von Braun et al. (2011)

55 C NC Habitable Zone 14 June 2011 K. von Braun -- Corot 2011 Marseile 9 Orbital parameters from Dawson & Fabrycky (2010) Habitable Zone von Braun et al. 2011

55 C NC Transiting Planet 14 June 2011 K. von Braun -- Corot 2011 Marseile 10 Orbital parameters from Dawson & Fabrycky (2010)

55 C NC 14 June 2011 K. von Braun -- Corot 2011 Marseile 11 von Braun et al. 2011, astro-ph/

55 C NC 14 June 2011 K. von Braun -- Corot 2011 Marseile 12 Winn, Matthews et al (updated version)

S UMMARY : U NDERSTAND THE P ARENT S TARS 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. 14 June 2011 K. von Braun -- Corot 2011 Marseile 13