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Spitzer Observations of Extrasolar Planets

Joseph Harrington University of Central Florida. Spitzer Observations of Extrasolar Planets. Credit: NASA / JPL-Caltech / R. Hurt (SSC-Caltech). Why Study Extrasolar Planets?. Search for Life? Astronomers have been selling life for 400 years!

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Spitzer Observations of Extrasolar Planets

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  1. Joseph Harrington University of Central Florida Spitzer Observationsof Extrasolar Planets Credit: NASA / JPL-Caltech / R. Hurt (SSC-Caltech)

  2. Why Study Extrasolar Planets? • Search for Life? • Astronomers have been selling life for 400 years! • $trong public motivator • New phase space for planetary science • Interior composition & dynamics • Atmospheric chemistry (Fe, enstatite clouds) • Atmospheric radiative chemodynamics! • Orbital dynamics, habitability, formation © 1997 Warner Bros.

  3. Challenge: Direct Observation

  4. Do the Numbers (R/a)2 is usually very small! Options: A: Increase t B: Reduce a or increase R by choice of planet C: Increase L or reduce d by choice of star D: Do something smarter than comparing reflected light Correct answer: E: All of the above!

  5. Trick: Transits! Get i, M, R Brown et al. (2001)

  6. Trick: Secondary Eclipses!

  7. Trick: Secondary Eclipses!

  8. Contrast Models Fortney et al. (2006)

  9. First Measured Photons I • Deming, Seager, Richardson, Harrington • Nature 434, 740-743 (2005) • HD 209458 b • Spitzer MIPS, 24 µm,1282 mid-IR array • 1696 good images over 6 hours • 10-sec exposures • 1.5 h pre-eclipse, 3 h eclipse, 1.5 h post-eclipse

  10. Data Deming et al. (2005b)

  11. HD 209458 b Results F24 m = 55 ± 10 µJy FP/F* = 0.0026 ± 0.00046 TB,24 m = 1130 ± 150 K tSE = t=0 + P/2 ± 7 min Significant orbital eccentricity very unlikely Inflated radius not likely due to another planet Primary eclipses consistent w/ optical result (Richardson et al. 2006, ApJ)

  12. First Measured Photons II! • Charbonneau et al. submitted TrES-1 the same day! • 2 wavelengths (4.5 and 8 µm) simultaneously • IRAC rather than MIPS, aperture photometry • FP/F*: 4.5 µm: 0.00066 ± 0.00013, 8 µm: 0.00225 ± 0.00036 • Tb = 1060 ± 50 K • A = 0.31 ± 0.14 • e = 0 Credit: NASA / JPL-Caltech / R. Hurt (SSC-Caltech)

  13. New Champ: HD 189733 b • Announced 2005 Oct 4, Bouchy et al. (French) • K1-K2 star (small, cool) • Rp = 1.26 RJup (bigish for a hot Jupiter) • Close (19.3 pc), V = 7.67 • Many times higher S/N than HD 209458 b • Good enough for spectroscopy!

  14. HD 189733 b 16 µm Data Deming et al. (2006)

  15. HD 189733 b is round! • Derivative of lightcurve shows planet crossing limb • Detect that planet is round • Cannot detect difference between uniform and peaked emission • Should be able to with IRAC data • Constrains hot-point lag Deming et al. 2006

  16. HD 149026 b: The Exotic Planet • Announced 2005 July 1, Sato et al. (Fischer/N2K) • Saturn-sized, but much heavier: ~80 M⊕ core! • Large G star → very weak eclipse (0.003 mag) N2K team, 2005 N2K team, 2005

  17. Spitzer Observations • Predicted 3-6 in one eclipse, most favorable band • Bright star → IRAC 8-µm subarray mode, 3232 pix • 48,384 frames, 0.4-sec frame rate, 6 h • Do not expect to see eclipse in raw data!

  18. Digging

  19. Model

  20. Eclipse!

  21. Temperatures Extrasolar Planets Encyclopedia, Deming et al. (2006,2005b), Charbonneau et al. (2005a)

  22. Upsilon Andromedae b Team Joseph Harrington, University of Central Florida, Cornell Brad Hansen, UCLA Statia Luszcz, Cornell, UC Berkeley Sara Seager, Carnegie Institution of Washington Drake Deming, NASA's Goddard Space Flight Center Kristen Menou, Columbia James Y.-K. Cho, Queen Mary, University of London L. Jeremy Richardson, NASA's Goddard Space Flight Center Image and animation: NASA/JPL-Caltech/Robert Hurt

  23. Fire and Ice on Upsilon Andromedae b • Upsilon Andromedae b: “hot Jupiter” planet • Observed at 24 m by Spitzer Space Telescope, MIPS instrument (Multiband Imaging Photometer for Spitzer) • Brightness variation tells us there is a "hot spot" facing the star • Very different from Jupiter: Huge temperature swings from day to night side (1400 K) Consistent with 0 phase lag (11  15)

  24. Upsilon Andromedae b Observations • First measurement of light from a non-transiting extrasolar planet • More, brighter planets now measurable by Spitzer • First detection of temperature variation on an extrasolar planet • Birth of exoplanetary meteorology: radiation dominates advection • Spitzer pushed well beyond specs

  25. Spitzer SE Spectroscopy • Divide that booming signal into a few hundred channels... • But also divide stellar and zodi • Stare as planet goes behind star • HD 209458b (Richardson et al. 2007, Nature) • HD 189733b (Grillmair et al. 2007, ApJ) • HD 209458b (Swain et al. 2007 submitted)

  26. HD 209458b • 2 eclipses • Detect continuum • Tentatively detect 2 molecular emissions! (first)

  27. HD 189733b • Continuum • NO molecular claim • NOTE: Models say won't see water that is there

  28. Conclusions • Spitzer can do more than it was designed to do • Spitzer can only do planets around nearby stars! • We have one more year of cold Spitzer • Most important survey goal this year: • FIND ALL THE NEARBY TRANSITING PLANETS • Going forward, no more Hubblephobia: • STOP UNDERSPECING INSTRUMENTS! • Pay for what you can get

  29. Ads • DPS 2007 is in Orlando! • Special Session on Exoplanets • Tuesday, 9 October 2007 • and... • UCF is looking for grads, postdocs, faculty! • Funds for dedicated 50-100 CPU cluster

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