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



                                          Nick Cowan
                                      CIERA Postdoctoral Fellow
with Louis Shekhtman (NU undergrad)    Northwestern University
Machalek, Croll, Burrows, Deming         September 15th 2011
 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
                 QuickTime™ an d a
                                                              • Peculiar Eclipse Depths:
                    decompressor
           are need ed to see this picture .
                                                                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
                             Li et al. (2010)                     Petigura 33.03
                                                                  Moses 40.04

Sept 15, 2011                                  Nick Cowan's Talk at ESS II                                  2
Thermal + Ellipsoidal Variations

                                                       Brightness Phases:
                                                       Planet Light
      Optical Light Observations
      • Reflected Light Dominates Phases
      • Star’s Shape Dominates Geometry
                                                      Geometrical Phases:
                                                      Projected Area
      Infrared Observations
      • Thermal Emission Dominates Phases
      • Planet’s Shape Dominates Geometry

                                           HAT-P-7b as seen by Kepler
                                           (Welsh et al. 2010)

Sept 15, 2011       Nick Cowan's Talk at ESS II                    3
   Raw WASP-12b Photometry
                                                         Phase Function

                                                   Eclipse
                                                                  Eclipse
                    3.6 micron                     4.5 micron   Transit




                Intra-pixel sensitivity variations
                are the dominant systematic
                1. Gaussian Decorrelation (Ballard et al. 2010)
                2. Polynomial in Centroid x and y

Sept 15, 2011             Nick Cowan's Talk at ESS II                 4
        WASP-12b at 3.6 micron

         Atherm/<Fp> = 0.9(3)
                                                     max = -53(7)°




Sept 15, 2011          Nick Cowan's Talk at ESS II                    5
What Planets Are Supposed To Do




                                                            Cowan & Agol (2011a)
                 Increasing Heat Capacity
                 1) Decreases Thermal Phase Amplitude
                 2) Increases Hot Spot Offset



                  Midnight        Dusk SOP        Noon   Dawn
                  SOP                             SOP    SOP
 Sept 15, 2011      Nick Cowan's Talk at ESS II                                6
        WASP-12b at 3.6 micron

         Atherm/<Fp> = 0.9(3)
                                                     max = -53(7)°




                                            Aellips = 2(2)x10-4




Sept 15, 2011          Nick Cowan's Talk at ESS II                    7
        WASP-12b at 4.5 micron

            Atherm/<Fp> = 0.7(1)
                                       max = -16(4)°
          Consistent with Cowan & Agol (2011a) Toy Model

                         The Null Hypothesis

                                                 Aellips = 1.2(2)x10-4




Sept 15, 2011           Nick Cowan's Talk at ESS II                      8
Interpreting Ellipsoidal Variations
                                4.5 micron phase variations
Phases




                                           cos(2) all due
                         most of cos(2) due to geometry to geometry
   Brightness Geometry




                                       Spherical planet

                             Temperature profile is cos(- 0)
                         But applying Cowan & Agol (2008) deconvolution
                                 All of cos(2) due to temperature
                         leads to unphysical longitudinal brightness map
                                some of cos(2) due to temperature

      Sept 15, 2011                   Nick Cowan's Talk at ESS II      9
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)




Sept 15, 2011                         Nick Cowan's Talk at ESS II                           10
          Transmission Spectrum
                                                          Transit Spectrum Assuming
                                                          Day-Like T-P Profile
                (Maciejewski et al. 2011)
                                                          (Burrows et al. 2007, 2008)




           (Chan et al. 2011)




Sept 15, 2011                    Nick Cowan's Talk at ESS II                            11
 Choose Your Own Adventure
  1. Prediction-Buster                   2. Null Hypothesis
• Roche-Lobe Opaque at                 • Ellipsoidal
  4.5 m + Gravity                       Variations As
  Brightened Terminator
                                         Predicted
• Weird Composition (not
  just high C/O)                       • Solar Composition?



                        QuickTime™ and a
                          decompressor
                  are neede d to see this picture.




Sept 15, 2011     Nick Cowan's Talk at ESS II             12
      WASP-12b Power Budget
                Eclipse Observations
                         AB ≈ 0.25
                          ≈ rad/(adv + rad) ≈ 0.1
                      Phase Observations
Hot Planets are Poor Recirculators (Cowan & Agol 2011b)
1. Magnetic Drag (Perna et al. 2010, Menou 2011)
2. Short Radiative Timescale (rad ≈ T-3)




Sept 15, 2011               Nick Cowan's Talk at ESS II   13
                  EXOCLIMES 2012
                     Aspen, CO
                   Jan 16-20, 2012




Registration Open
www.aspenphys.org
  Sept 15, 2011       Nick Cowan's Talk at ESS II   14

				
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