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WARM SPITZER PHASE VARIATIONS OF WASP-12B: DEFYING PREDICTIONS

This talk explores the various phase variations of WASP-12b, a tortured world with a one-day orbit and peculiar eclipse depths. It discusses the thermal and ellipsoidal variations, as well as the day-side emergent spectrum and transmission spectrum of the planet. It also presents different hypotheses and power budgets related to the observations of WASP-12b.

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WARM SPITZER PHASE VARIATIONS OF WASP-12B: DEFYING PREDICTIONS

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  1. WARM SPITZER PHASE VARIATIONS OF WASP-12B: DEFYING PREDICTIONS Nick Cowan CIERA Postdoctoral Fellow Northwestern University September 15th 2011 with Louis Shekhtman (NU undergrad) Machalek, Croll, Burrows, Deming

  2. WASP-12b: a Tortured World • ~1 day orbit: Oblate Planet • Tidally Warped: Prolate Planet • Tday≈3000 K: MHD Effects • Big Rp, small a: Roche-Lobe Overflow • Accretion on Star/ Bow Shock • Peculiar Eclipse Depths: High C/O ratio (Hebb et al. 2009; Ragozzine & Wolf 2009; Li et al. 2010; Lai et al. 2011; Leconte et al. 2011; Fossati et al. 2010; Vidotto et al. 2010; Llama et al. 2011; Madhusudhan et al. 2011) Check Out These Posters: Crossfield 40.08 Petigura 33.03 Moses 40.04 Li et al. (2010) Nick Cowan's Talk at ESS II

  3. Thermal + Ellipsoidal Variations Brightness Phases: Planet Light • Optical Light Observations • Reflected Light Dominates Phases • Star’s Shape Dominates Geometry • Infrared Observations • Thermal Emission Dominates Phases • Planet’s Shape Dominates Geometry Geometrical Phases: Projected Area HAT-P-7b as seen by Kepler (Welsh et al. 2010) Nick Cowan's Talk at ESS II

  4. Raw WASP-12b Photometry Phase Function Eclipse Eclipse 3.6 micron 4.5 micron Transit Intra-pixel sensitivity variations are the dominant systematic Gaussian Decorrelation (Ballard et al. 2010) Polynomial in Centroid x and y Nick Cowan's Talk at ESS II

  5. WASP-12b at 3.6 micron Atherm/<Fp> = 0.9(3) max = -53(7)° Nick Cowan's Talk at ESS II

  6. What Planets Are Supposed To Do Increasing Heat Capacity 1) Decreases Thermal Phase Amplitude 2) Increases Hot Spot Offset Noon SOP Dawn SOP Midnight SOP Dusk SOP Cowan & Agol (2011a) Nick Cowan's Talk at ESS II

  7. WASP-12b at 3.6 micron Atherm/<Fp> = 0.9(3) max = -53(7)° Aellips = 2(2)x10-4 Nick Cowan's Talk at ESS II

  8. WASP-12b at 4.5 micron Atherm/<Fp> = 0.7(1) max = -16(4)° The Null Hypothesis Consistent with Cowan & Agol (2011a) Toy Model Aellips = 1.2(2)x10-4 Nick Cowan's Talk at ESS II

  9. Interpreting Ellipsoidal Variations most of cos(2) due to geometry cos(2) all due to geometry Spherical planet 4.5 micron phase variations Phases Geometry Temperature profile is cos(- 0) But applying Cowan & Agol (2008) deconvolution leads to unphysical longitudinal brightness map Brightness All of cos(2) due to temperature some of cos(2) due to temperature Nick Cowan's Talk at ESS II

  10. Day-Side Emergent Spectrum Null Hypothesis (Campo et al. 2010) This Study (López- Morales et al. 2010) (Croll et al. 2011) Day-Side 1D Model Spectra (Burrows et al. 2007, 2008) Nick Cowan's Talk at ESS II

  11. Transmission Spectrum Transit Spectrum Assuming Day-Like T-P Profile (Burrows et al. 2007, 2008) (Maciejewski et al. 2011) (Chan et al. 2011) Nick Cowan's Talk at ESS II

  12. Choose Your Own Adventure 1. Prediction-Buster Roche-Lobe Opaque at 4.5 m + Gravity Brightened Terminator Weird Composition (not just high C/O) 2. Null Hypothesis Ellipsoidal Variations As Predicted Solar Composition? Nick Cowan's Talk at ESS II

  13. WASP-12b Power Budget Eclipse Observations AB ≈ 0.25  ≈ rad/(adv +rad) ≈ 0.1 Phase Observations Hot Planets are Poor Recirculators (Cowan & Agol 2011b) Magnetic Drag (Perna et al. 2010, Menou 2011) Short Radiative Timescale (rad ≈ T-3) Nick Cowan's Talk at ESS II

  14. EXOCLIMES 2012Aspen, COJan 16-20, 2012 Registration Open www.aspenphys.org Nick Cowan's Talk at ESS II

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