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Observational Constraints on the Formation and Properties of Giant Planets Jeff Valenti

Observational Constraints on the Formation and Properties of Giant Planets Jeff Valenti. Road Map for the Talk. Orbital Properties of Planets Observed Planet-Metallicity Relationship Two competing planet formation theories We measured lots of stellar abundances

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Observational Constraints on the Formation and Properties of Giant Planets Jeff Valenti

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  1. Observational Constraints on the Formation and Properties of Giant PlanetsJeff Valenti

  2. Road Map for the Talk • Orbital Properties of Planets • Observed Planet-Metallicity Relationship • Two competing planet formation theories • We measured lots of stellar abundances • Higher metallicity stars have more detected planets! • Not caused by accretion of rocky debris • Timescale for Building Gas Giant Planets • Our HST detection of hot H2 • Characterizing Transiting Planets • My HST program to observe an evaporating exosphere • JWST spectra of atmospheric absorption and emission

  3. Planet Discovery N2K, Ge PLANET consortium SWEEPS, XO

  4. Planets Migrate! “Snow Line” Pile-up at P=3 days http://exoplanets.org/a_hist.gif

  5. Disk is Truncated by Stellar Magnetosphere Milky Way & Cookies Monday, April 3 Shu et al. (1994)

  6. Two Theories of Planet Formation Metals: 0.1 nm Core-Accretion Dust: 1 nm – 1 mm Planetesimals: 1 mm – 1 km Cores: 1 km – 1 Mm Do Metals Matter ? crit nH Planets : 1 Mm – 0.1 Gm Gravitational Instability

  7. Spectroscopic Analysis Tool • SME - “Spectroscopy Made Easy” • Valenti & Piskunov (1996, A&AS, 118, 595) • Publicly available • Radiative transfer code [with Nikolai Piskunov] • LTE, Feautrier solver, Adaptive λ grid, C++ • Chemical equilibrium for over 150 molecules (NextGen EOS) • Fit observed spectrum with synthetic spectrum • Use precise atomic data from solar spectrum fit • Interpolate Kurucz atmospheres in Teff, logg, and [M/H] • Calculate synthetic intensities across the stellar surface • Integrate over stellar surface: rotation and RT macroturbulence • Non-linear least squares solver (Levenberg-Marquardt) • Free parameters: log(gf), Teff, logg, [M/H], etc.

  8. Determining Spectroscopic Properties Segment #1 Segment #2 Valenti & Fischer (2005)

  9. Stellar Macroturbulence Valenti & Fischer (2005)

  10. Isochrone Analysis 1040 Stars T, L, Fe,  M, R, age

  11. Spectroscopic Properties of Cool Stars • Valenti & Fischer (2005, ApJS, 159, 141) • 1807 observed spectra (6 CPU months) • 1040 nearby dwarfs and subgiants • N2K: 410 Keck + 400 Subaru + 270 Magellan spectra analyzed • Properties based on fitting spectra • Effective temperature (1%) • Surface gravity (15%) • Rotational velocity (0.5 km/s) • Abundances: Na, Si, Ti, Fe, Ni (5-10%) • Properties based on matching evolutionary models • Stellar mass (15%) • Radius (3%) • Age constraints

  12. Metals in Full Sample and Stars with Planets

  13. p = (10[Fe/H]) = (N(Fe) M)  = (4.5 ± 0.8)%  = (1.8 ± 0.3) N(Fe) M Quadratic Dependence on Stellar Metals Increasing metals by 40% doubles the number of stars with planets Fischer & Valenti (2005)

  14. Dependence on Stellar Mass? Fischer & Valenti (2005) Cooler Stars Metallicity bias…

  15. 0.6 0.4 0.2 [M/H] 0.0 -0.2 -0.4 -0.6 6500 6000 5500 5000 TEFF (K) Does Accretion Cause Planet-Metallicity Relationship? Pinsonneault, De Poy, & Coffee (2001) 1 M Stars with Planets

  16. 0.0 2.0 Mbol 4.0 6.0 8.0 6500 6000 5500 5000 TEFF (K) Subgiants with and without Planets Subgiants Planets

  17. 0.6 0.2 [Fe/H] -0.2 -0.6 6500 6000 5500 5000 4500 TEFF (K) Subgiant Test – No Diluted Enrichment Subgiants with planets are still metal rich [Fe/H]=0.15

  18. Velocity Precision vs. Metallicity

  19. Line Depths NOT Proportional to Abundance Strong Lines are Saturated

  20. Metals Do Not Affect Migration Stopping Point

  21. Stars with Distant Planets Seem To Be Metal Rich Statistics are improving where giant planets form. 3% of Keck sample has long period planets

  22. Next Step: Detection Limits for Each Star Adapted from Cumming (2004, MNRAS, 354, 1165) P < 4 yr FV05 N=15 N=30 K > 30 m/s 30 m/s p=99% p=50%

  23. Classical Core-Accretion Model Is Slow Pollack et al. (1996) Phase I Core formation via rapid accretion of planetesimals in “feeding zone” Phase III Giant planet formation via rapid gas accretion Phase II Envelope formation via gradual gas accretion Core + Envelope Core Only Isolation Mass

  24. Dust Near a Star Dissipates Quickly Warm dust only lasts “a few Myr” How long does the gas last? Haisch, Lada, & Lada (2001)

  25. Hot Inner Edge(s) of Disks SU Aur RY Tau Akeson et al. (2006)

  26. Molecular Hydrogen in Accretion Disks Herczeg et al. (2002; 2004; 2005)

  27. Ly- Pumped Fluorescence of Hot H2 Herczeg et al. (2004)

  28. Ly- Pumped Fluorescence of Hot H2 Herczeg et al. (2004)

  29. Comparative Planetology • Find planets that transit bright (V<12) stars • Absorption by planetary atmosphere during transit • Thermal emission in and out of secondary eclipse • 1)HD209458b, 2) TrES-1, 3) HD189733b, 4)HD149026b • N2K Survey • Fischer (SFSU), Laughlin (UCSC), Valenti (STScI), … • Surveying the “next 2000” stars, V<10.5 (14,000 candidates) • Constructed metal-rich sample using photometric indexes • “Three strikes and you’re out!” - focus on short periods • So far: 410 Keck + 400 Subaru + 270 Magellan stars • So far: 7 planets announced + 3 in press + 36 candidates • So far: 1 new transiting planet!

  30. HD 149026 40 Velocity (m/s) 0 –40 Subaru&Keck –0.5 0.0 0.5 Orbital Phase “N2K” Discovers Its First Transiting Planet! Sato et al. (2006)

  31. Diversity of Planets - Formation vs. Evolution Evaporating Exosphere Program 10718 Bouchy et al. (2005)

  32. Evaporating Exospheres Vidal Madjar et al. (2003)

  33. Planetary Transits with JWST/NIRSpec R=3000 Brown (1991)

  34. Planetary Eclipses with JWST/NIRSpec R=3000 Spitzer

  35. Key Results • Spectroscopic Properties of Cool Stars (SPOCS) • 1040 solar-type stars in Keck, Lick, AAT planet search programs • Analyzing another 2000 stars in N2K program • Quantified Planet-Metallicity Relationship • Increasing metals by 40% doubles the number of stars with planets • Not due to preferential accretion of metals onto star • Inconsistent with gravitational instability (migration?) • Fundamental constraint on all formation models • HST andJWST will characterize disks and atmospheres • Use fluoresced H2 to study gas in protoplanetary disks • Measure extent of planetary exosphere during transit • Obtain atmospheric absorption spectra during transit • Measure thermal emission spectra in/out of secondary eclipse

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