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Christopher M. Johns-Krull (Rice University)

Exploring the Planet Forming Environments of Young Suns. Christopher M. Johns-Krull (Rice University). IGRINS Science Workshop: August 26, 2010. Star and Planet Formation. Central Engine & Fate of Disk. Lost in an Outflow. Edwards et al. (1994). Shu et al. (1994). Disk locking.

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Christopher M. Johns-Krull (Rice University)

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  1. Exploring the Planet Forming Environments of Young Suns Christopher M. Johns-Krull (Rice University) IGRINS Science Workshop: August 26, 2010

  2. Star and Planet Formation

  3. Central Engine & Fate of Disk Lost in an Outflow Edwards et al. (1994) Shu et al. (1994) Disk locking Incorporated into Planets Accreted onto Star

  4. Stellar Magnetic Fields

  5. Theoretical Predictions Konigl (1991): Cameron & Campbell (1993): Shu et al. (1994):

  6. Measuring Fields from the Zeeman Effect

  7. Zeeman Desaturation of Optical Lines EQ Vir Tap 35 Bf = 1.7 kG Bf = 1.5 kG Model with B/Model Without B LkCa 16 • Basri et al. (1992): 2 TTS • Basri & Marcy (1994): Several dKe stars • Guenther et al. (1999): 4 TTS • Very sensitive to Teff Bf = 0? kG

  8. Direct Zeeman Broadening Initial optical 2 line analyses were faulty

  9. M Dwarf Fields in the Optical Johns-Krull & Valenti (1996, ApJ, 459, L95) Fe I TiO TiO s McDonald Observatory 2dCoude s Ti I vsini= 4.5 km/s

  10. Getting Rid of the TiO Johns-Krull & Valenti (1996, ApJ, 459, L95) McDonald Observatory 2dCoude

  11. Going to the Infrared • Kitt Peak 4m + FTS & NASA IRTF (3m) + CSHELL spectrometer • R ~ 35,000-44,000 spectra • Excess Broadening Seen in the Ti I line Johns-Krull et al. (1999) Saar & Linsky (1985)

  12. TW Hya: CTTS Yang, Johns-Krull, & Valenti (2005)

  13. Hubble 4: NTTS Johns-Krull, Valenti, & Saar (2004)

  14. Predicted vs. Observed Mean Fields • Caveats: • Theory assumes dipole • We measure mean field • Uncertainty on x-axis difficult to quantify • Additionally: no correlation with rotation rate, Rossby number, etc. Johns-Krull (2007)

  15. YSOs in Other Regions Yang & Johns-Krull (2010) Johns-Krull et al. (2009) WL 17 B = 2.9 kG V1348 Ori B = 3.3 kG Yang et al. (2008) TWA 9A B = 3.2 kG V1123 Ori B = 2.8 kG

  16. Building Planets: Mechanisms Gravitational Instabilities Timescale? Core Accretion

  17. The Brown Dwarf Desert Grether and Lineweaver (2006)

  18. Observational Clues  Core Accretion: Dust collides and sticks together, building up larger bodies. May take about 10 Myr to build Jupiter. X GI: Gravitational instability leads to rapid planet formation. Santos et al. (2004) Fisher & Valenti (2005)

  19. Observational Clues Marois et al. (2008) HR 8799 Dodson-Robinson et al. (2009) HL Tau X Core Accretion: Dust collides and sticks together, building up larger bodies. May take about 10 Myr to build Jupiter. X GI: Gravitational instability leads to rapid planet formation. Greaves et al. (2008)

  20. Origin of the Desert • Some feature (disk mass, disk lifetime, etc.) of the planet formation process prevents brown dwarfs forming • Brown dwarfs do form, but then migrate in (Armitage & Bonnell 2002)

  21. Search for Planets Around Young Stars

  22. Young Star Properties • ages 1-few Myr • rotation periods 1-15 days • visible photospheres • classical & weak T Tauri Stars Valenti et al. (1993) Photometric Variability Herbst et al. (2002)

  23. McDonald Young Planet Search Approach: Harlan J. Smith 2.7m telescope • Coude spectrograph for stability • observe faint and bright RV standards for uncertainties • Th-Ar comps & cross correlation analysis Collaborators: Lisa Prato (Lowell Observatory) Naved Mahmud (Rice University) Chris Crockett (Lowell Observatory) Pat Hartigan (Rice University) Dan Jaffe (University of Texas) Marcos Huerta (AAS)

  24. Testing the Approach • RV standards show RMS ~120 m/s • proof of concept: exoplanet HD 68988b (Butler+ 06) • P=6.28d • K=191m/s

  25. Very Large Spots • young, low-mass stars fully convective • rotating rapidly • convection and rotation drive strong dynamo & superspots • observed photometrically and spectroscopically V410 Tau

  26. Very Large Spots • young, low-mass stars fully convective • rotating rapidly • convection and rotation drive strong dynamo & superspots • observed photometrically and spectroscopically Hatzes (1995) V410 Tau

  27. Spots and Reflex Motion Line distortions also lead to apparent radial velocity variations

  28. Can We Tell the Difference? • yes (maybe!) • spots induce spectral line asymmetries • bisector span should correlate with the radial velocity if a spot is present

  29. Young RV Planets to Date • Setiawan et al. (2007) identified long period (852d) planet around 100 Myr old star HD 70573 • In 2008 team claimed detection of a 10MJ, 10 Myr old planet @ TW Hya

  30. Some Results • No brown dwarf companions yet Huerta et al. (2008) • Some clearly spotted stars!

  31. Brown Dwarf: LP 944-20 Martín et al. (2006)

  32. Infrared Spectroscopy • CSHELL spectrograph, cassegrain mounted on telescope • flexure? No I2 cell • need Earth’s telluric lines for  calibration (e.g., Blake et al. 2007, 2008)

  33. Infrared Spectroscopy Model composite target spectrum with combination of stellar template (sunspot spectrum) and observed telluric spectrum (Prato et al. 2008) RV Precision • Nov 2008: 61 m/s • Feb 2009: 31 m/s • Nov 2009: 44 m/s • Feb 2010: 97 m/s • Overall: 69 m/s

  34. Ruling Out Interesting Candidates Prato et al. (2008) V827 Tau DN Tau

  35. -400 +400 Radial Velocity (m/s) TW Hya: Planet or Spot? • Setiawan et al. (2008): no line bisector radial velocity correlation? • Huelamo et al. (2008): find correlation between line bisector and radial velocity

  36. IR RV Variations Due to Spots V827 Tau Hubble 4

  37. High Precision IR RV Bean et al. (2010)

  38. Thank You

  39. Disks Are Commonly Observed

  40. From Disks to Planets

  41. Measuring Stellar Magnetic Fields

  42. Field Geometry: Polarization

  43. The Photospheric Field of BP Tau

  44. Emission Line Polarization He I Polarization Like looking only at the sunspots

  45. Can “Map” the Stellar Field 7 nights in November 2009

  46. K and M Star Results • Field strength set by pressure balance with quiet photosphere • Excellent Correlation with X-ray emission • f and Bf correlated with rotation Saar (1996) Pevtsov et al. (2003)

  47. Transition Disks Marois et al. (2008) HR 8799 Kalas et al. (2008) NASA

  48. Transition Disks Najita et al. (2007)

  49. Transition Disks Najita et al. (2007)

  50. Accretion onto the Star f ~ 0.01 A T Tauri star Gullbring et al. (1998) Valenti et al. (1993) Garcia-Lopez et al. (2006)

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