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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 Incorporated into Planets Accreted onto Star Stellar Magnetic Fields Theoretical Predictions Konigl (1991): M* B* 3.43 7/6 7/4 0.35 0.5 1M 5/6 1/2 R* M -7 -1 10 M yr 1.0R -3 P* kG 1.0d 7/6 Cameron & Campbell (1993): -1/3 M * B* 1.10 1M 2/3 23/40 R* M -7 -1 10 M yr 1R -3 P* 1d 29/24 kG Shu et al. (1994): B* 3.38 x 0.923 -7/4 M* 1M 5/6 1/2 R* M -7 -1 10 M yr 1R -3 P* kG 1d 7/6 Measuring Fields from the Zeeman Effect Zeeman Desaturation of Optical Lines EQ Vir Tap 35 Bf = 1.5 kG Bf = 1.7 kG Model with B/Model Without B • Basri et al. (1992): 2 TTS LkCa 16 • Basri & Marcy (1994): Several dKe stars • Guenther et al. (1999): 4 TTS • Very sensitive to Teff Bf = 0? kG Direct Zeeman Broadening Initial optical 2 line analyses were faulty M Dwarf Fields in the Optical Johns-Krull & Valenti (1996, ApJ, 459, L95) TiO s Ti I s TiO vsini = 4.5 km/s McDonald Observatory 2dCoude Fe I Getting Rid of the TiO Johns-Krull & Valenti (1996, ApJ, 459, L95) McDonald Observatory 2dCoude 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) TW Hya: CTTS Yang, Johns-Krull, & Valenti (2005) Hubble 4: NTTS Johns-Krull, Valenti, & Saar (2004) Predicted vs. Observed Mean Fields Johns-Krull (2007) Caveats: • Theory assumes dipole • We measure mean field • Uncertainty on xaxis difficult to quantify Additionally: no correlation with rotation rate, Rossby number, etc. YSOs in Other Regions Yang & Johns-Krull (2010) WL 17 B = 2.9 kG Johns-Krull et al. (2009) TWA 9A B = 3.2 kG Yang et al. (2008) V1348 Ori B = 3.3 kG V1123 Ori B = 2.8 kG Building Planets: Mechanisms Gravitational Instabilities Timescale? Core Accretion The Brown Dwarf Desert Grether and Lineweaver (2006) 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) Observational Clues HR 8799 HL Tau Dodson-Robinson et al. (2009) Marois et al. (2008) X Core Accretion: Dust Greaves et al. (2008) 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. 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) Search for Planets Around Young Stars 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) McDonald Young Planet Search Approach: • 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) Harlan J. Smith 2.7m telescope Testing the Approach • RV standards show RMS ~120 m/s • proof of concept: exoplanet HD 68988b (Butler+ 06) • P=6.28d • K=191m/s Very Large Spots • young, low-mass stars fully convective • rotating rapidly • convection and rotation drive strong dynamo & superspots • observed photometrically and spectroscopically V410 Tau Very Large Spots • young, low-mass stars fully convective • rotating rapidly • convection and rotation drive strong dynamo & superspots • observed photometrically and spectroscopically V410 Tau Hatzes (1995) Spots and Reflex Motion Line distortions also lead to apparent radial velocity variations 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 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 Some Results • No brown dwarf companions yet Huerta et al. (2008) • Some clearly spotted stars! Brown Dwarf: LP 944-20 Martín et al. (2006) 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) 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 Ruling Out Interesting Candidates Prato et al. (2008) V827 Tau DN Tau TW Hya: Planet or Spot? -400 • Setiawan et al. (2008): no line bisector radial velocity correlation? • Huelamo et al. (2008): find correlation between line bisector and radial velocity Radial Velocity (m/s) +400 IR RV Variations Due to Spots V827 Tau Hubble 4 High Precision IR RV Bean et al. (2010) Thank You Disks Are Commonly Observed From Disks to Planets Measuring Stellar Magnetic Fields Field Geometry: Polarization The Photospheric Field of BP Tau Emission Line Polarization He I Polarization Like looking only at the sunspots Can “Map” the Stellar Field 7 nights in November 2009 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 Pevtsov et al. (2003) Saar (1996) Transition Disks Marois et al. (2008) HR 8799 Kalas et al. (2008) NASA Transition Disks Najita et al. (2007) Transition Disks Najita et al. (2007) Accretion onto the Star M ~ 108 Msun yr -1 f ~ 0.01 A T Tauri star Gullbring et al. (1998) Valenti et al. (1993) Garcia-Lopez et al. (2006) T Tauri Stars: Magnetically Controlled Accretion • Rotation correlated with disk signatures Edwards et al. (1994) • Balmer line profiles • Accretion shock models reproduce optical veiling Shu et al. (1994) Disk locking Theory gives field at some point in the disk Shu et al. (1994) X-ray Luminosity vs Magnetic Flux Solar X-ray Bright Points Longcope et al. (2001) T Tauri Stars Johns-Krull & Valenti (2000) Solar Active Regions Fisher et al. (1998) Quiet Sun at Solar Minimum Pevtsov & Acton (2000) Pevtsov et al. (2003) F, G, and K Dwarfs Saar (1996) Collaborators Jeff Valenti (STScI) Hao Yang (JILA) Wei Chen (Rice) Lisa Prato (Lowell Observatory) Naved Mahmud (Rice University) Chris Crockett (Lowell Observatory) Pat Hartigan (Rice University) Dan Jaffe (University of Texas) Marcos Huerta (AIP/AVS)