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The Inner 200AU Environs of Classical T Tauri Stars Revealed by Gemini NIFS

The Inner 200AU Environs of Classical T Tauri Stars Revealed by Gemini NIFS Tracy L. Beck (STScI & Gemini Observatory) Peter J. McGregor (Australian National University) Michihiro Takami (ASIAA, Taiwan & Subaru Observatory). Molecular Hydrogen in YSO Environs.

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The Inner 200AU Environs of Classical T Tauri Stars Revealed by Gemini NIFS

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  1. The Inner 200AU Environs of Classical T Tauri Stars Revealed by Gemini NIFS Tracy L. Beck (STScI & Gemini Observatory) Peter J. McGregor (Australian National University) Michihiro Takami (ASIAA, Taiwan & Subaru Observatory)

  2. Molecular Hydrogen in YSO Environs First: Why do We Care about H2? • H2 is the dominant constituent of ANY cool gas! • Circumstellar YSO Disks = Cool Gas, Studies that seek to characterize future planet formation in YSO disks need to understand how the gas contributes to the evolution (trendy topic - many papers on “quiescent” near-IR H2 from CS disks in the last ~year, some sources with known outflows) • Quiescent H2 gas in the solar-system (>~30AU) regions of YSO disks should be spatially resolvable in the near-IR using present technologies • Little is known about the relation between quiescent H2 in planet-forming disks versus shocked emission in YSO outflows TBeck, AAS

  3. Where Does H2 Arise From in YSO Environments? H2 From Quiescent emission in a Disk (or disk gap) H2 From Shocks in Outflows H2 H2 H2 H2 H2 30-50 AU H2 H2 Bow Shock H2 10’s, even 100’s of AU Outflow star star Circumstellar Disk Circumstellar Dust Disk Disk gap cleared by forming planets? H2 Fluorescently pumped by stellar UV/Ly flux or heated by UV/Xrays H2 Excited into LTE emission by shocks TBeck, AAS

  4. H2 in the Inner 200 AU Environs of CTTSs’ • UV/IR Observations suggest moderate amounts of H2 emission excited by Lypumping,UV Fluorescence and/or Xray heating in the inner ~30-50 AU from a star (Herczeg et al. ‘04; ‘06; Walter et al. ‘03; Bary et al. 2003) • Seeing-limited spectra of near IR H2 suggest emission from thermal populations with T~2000K - gas in LTE from Shocks (Davis et al. ‘00; ‘01; Takami et al. ‘04; ‘06) • Relationship between ro-vibrational IR H2 emission, UV H2 electronic features, and pure rotational emission detected in the mid-IR? Existing H2 data consists of different wavelength regimes, different sensitivities, & different spatial and spectral resolutions. & H2 could be intrinsically time variable. TBeck, AAS

  5. H2 Lines Detected in the IR K-band (2.0-2.45 m) TA Brief reminder on H2 level populations • Ro-vibrational diagram of the first electronic level in the H2 molecule • Features detectable in the IR K-band include v=1-0, 2-1 and 3-2 transitions • V=1-0 S(1) at 2.12 microns is the brightest IR transition • Significant level population in the high v and high J states in K-band spectra is characteristic of non-thermal excitation in YSO environments • Emission Line ratios provide information on excitation (2-1 S(1)/1-0S(1)) and line of sight extinction toward the H2 emitting regions V=2-1 S(1) V=1-0 Q(3) & S(1) TBeck, AAS

  6. H2 in the inner regions of YSOs Virtually EVERY wavelength regime used for the study of H2 emission starts out with: T TAU! Eponymous T Tauri, sub arcsec triple system Near IR ground-based spectra, H2 first detected in T Tau (Beckwith et al. 1978) IUE Spectra, UV H2 emission reported in young stars in T Tau (Brown et al. 1981) Mid IR Hi Res spectra, T Tau used as a prototype to search for H2 disk emission (TEXES Team, Richter et al. 2006)

  7. AO Studies of IR H2 in Inner (<1”) YSO Environments… v=1-0 S(1) transition at 2.12m at Adaptive Optics (<0.”1) spatial resolutions The # of published IR studies that accurately spatially resolve near IR H2 in the inner ~100AU can be counted on one hand) Longslit spectra at Hi Resolution Takami et al. 2005 -DG Tau - Spatially resolved knot of H2 emission ~60AU in extent from the central star Duchene et al., 2005 - T Tau - NIRSpec Keck spectroscopy of 2.12m emission near the T Tau South binary 2.12m H2 emission

  8. Resolved Near IR H2 in Inner YSO Environments… v=1-0 S(1) transition at 2.12m from Fabry-Perot Imaging Spectra at high spatial res Herbst et al. 2007 - (you guessed it, T Tau!) Circular apertures block out the flux from the stars Shocked H2, Identifies the southern T Tau binary as the source of the East-West Outflow

  9. A New Tool For Studying YSO Jets: Integral Field Spectroscopy! • Integral Field Units (IFUs) provide resolved imaging spectroscopy of YSOs on sub-arcsecond spatial scales and allow for: • Simultaneous spatial+kinematic information (near IR = numerous features: HI, H2, [FeII], HeI…) • A (small) 2D spatial field, much better than longslit • Extremely accurate continuum subtraction, much better than for narrow band filters • Broader spectral coverage than Fabry-Perot Imaging • IR Wavelengths can pierce through greater visual extinction toward a young star than UV. TBeck, AAS

  10. Integral Field Spectroscopy: The Age of the IFU at 8-10m Observatories! • In the last several years, 7 integral field optical & IR spectrographs have been commissioned at the major 8-10 meter class ground-based observatories! • GMOS-N (Gemini N) • GMOS-S (Gemini S) • VIMOS (VLT) • SPIFFI+SINFONI (VLT)*** • OSIRIS (Keck)*** • NIFS (Gemini N)*** • GNIRS (Gemini S/N… :-( ) *** AO-fed, diffraction limited spatially resolved IR spectroscopy TBeck, AAS

  11. Telescope focus Spectrograph input Spectrograph output Pupil imagery Lenslets, OSIRIS (Keck) Datacube slit y Lenslets + fibres GMOS (Gemini) VIMOS (VLT) Fibres  x 1 Image Slicer GNIRS, NIFS (Gemini), SPIFFI+SINFONI (VLT) slit Mirrors 2 3 4 1 2 3 4 Integral Field Spectroscopy: The Age of the IFU at 8-10m Observatories! NIFS 3” 3” TBeck, AAS Figure courtesy of J. Allington-Smith (U. of Durham)

  12. Most of you HAVE heard of NIFS… NIFS: A Remarkable Recovery! First Light! October 19, 2005 Total Destruction January 18, 2003 TBeck, AAS

  13. The Near Infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory • Near IR, AO-fed image slicing IFU for 1.0-2.5 micron spectra • R~5000 spectroscopy • 3” x 3” field with 0.”1x0.”04 (rectangular) Spatial Sampling • 1 pointing gives IFU spectra over one full IR band (Z, J, H or K) NIFS 3” R~5000 3” Individual Pixel Size 0.”04 TBeck, AAS 0.”10

  14. The Near Infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory NIFS • The 29 Slices of the Image slicer mirror hack the image field (in the x direction) into equivalently 29 “longslit” spectra that are stacked onto the detector (in y) 3” R~5000 3” NIFS raw image TBeck, AAS

  15. NIFS Data Format, 29 Spectra in One • NIFS H-band IFU Spectra of the young star, DG Tau [Fe II] in DG Tau TBeck, AAS

  16. NIFS K-band Observations of YSOs Data acquired in standard K-band setting for R~5000 spectra from 2.00 to 2.44m on: DG Tau - flexure test (> 12000sec!) HV Tau /C - NIFS sensitivity on spatially extended sources (2700s) RW Aur - Test for High S/N on continuum (440s) T Tau - NIFS Flexure Test (~4600s) XZ Tau - NIFS + OIWFS Guide Tests (820s) HL Tau - SV of Coronograph Observations (2700s) Most sources were known to have H2 emission, all are known HH outflow stars

  17. 2.12 micron Continuum Emission/2.12 micron H2 Emission Continuum Beck et al. 2008 FWHM=0.”12 TBeck, AAS

  18. 2.12 micron Continuum Emission/2.12 micron H2 Emission Continuum & H2 Spatially Extended H2 detected in ALL stars, and most is not coincident with continuum emission Using Adaptive Optics fed R~5000 K-band IFU spectroscopy with NIFS at Gemini North, we obtained IFU spectra of six “Classic” Classical T Tauri Stars: T Tau, DG Tau, RW Aur, HL Tau, XZ Tau and HV Tau C TBeck, AAS

  19. 2.12 micron Continuum Emission/2.12 micron H2 Emission • DG Tau in H2 emission: • A brighter “v-shaped” nebula encompassing the blue-shifted atomic jet, and a fainter “ridge” of emission on the red-shifted side of a “dark lane”. • Very reminiscent of “edge-on disk” morphologies seen in scattered light in young YSOs • Orientation of dark lane complete consistent with known disk orientation from mm observations (Testi et al. 02) DG Tau Blue-shifted Jet TBeck, AAS

  20. In addition to v=1-0S(1) at 2.12 m: Detection of Multiple H2features in ALL stars! HV Tau C: Nine v=1-0 and v=2-1 H2 features detected TBeck, AAS

  21. In addition to v=1-0S(1) at 2.12 m: Detection of Multiple H2features in ALL stars! T Tau: Demonstration of improved detectability of H2 features over bright continuum Blue = brightest continuum location Green = brightest H2 location (0.”2 apertures) TBeck, AAS

  22. H2 Morphologies • General Belief: H2 excited exclusively by flux from the central star (i.e. Ly or FUV fluorescence, X -ray heating) would decrease with increasing distance from the star, and completely undetected by a ~30-50AU distance (Tine et al. 1997; Maloney et al 1996; Nomura & Millar 2005). • HOWEVER - The emitting gas could be clumpy resulting in discrete knots of emission (rather than a smooth decrease) • Shocked H2 would show more spatially extended flux, with evidence for discrete knots. • HOWEVER - A wide-angle component to the outflow (I.e., a wind) could also smoothly decrease in flux from the central star • 5 of the 6 stars we observe have H2 that extends to > 100 AU! Morphology is important, but it is difficult in some cases to determine where the H2 is coming from solely based morphology TBeck, AAS

  23. H2 Morphologies H2 in RW Aur clearly traces the known HH Outflow. DG Tau’s H2 encompasses the known blueshifted flow - a wide angle outflow component? H2 Follows low velocity [SII] emission almost precisely More Difficult Not so Difficult DG Tau 1” RW Aur TBeck, AAS

  24. H2Excitation Temperatures In our obs. H2 Level Populations are best explained by populations in LTE with Tex ~1800K - 2300K (=2-1 S(1) (2.24m) / =1-0 S(1) (2.12m)Ratio ).05-0.1) TBeck, AAS

  25. H2 Kinematics Hypothesis: In YSO Environs,H2 Line Profiles should always be shifted in velocity from the stellar radial velocity if the emission is shock excited This is not correct - lack of velocity shift (>~10-15km/s) doesn’t rule out shock excitation. Shock models can explain the low velocity H2 emission component that has little or no velocity deviation from systemic. This can arise from slow winds close to the star, or fast on-axis gas in the outflow encompassed by slower, low velocity “wings” of molecular flow emission (Smith et al. 1995; 2003 Eisloffel et al. ‘00; Davis et al. 1994; 2000; 2001; Takami et al. 2007). H2 emission that is shifted in velocity from the stellar RV is shock excited in an outflow. TBeck, AAS

  26. Velocity Structure and Kinematics Only T Tau and RW Aur show evidence for H2 velocity structure. RW Aur - High and Low velocity gas comes from different spatial regions

  27. Spatially Resolved Near IR H2 Emission in the Inner 200 AU of Classical T Tauris • We detect spatially extended H2 in 6 of 6 Classical T Tauri stars, approximately tripling the number of stars with spatially resolved near IR H2 within <200AU • The majority of the H2 emission measured within the IFU field is not coincident with the location of K-band stellar continuum emission. • The H2 is in LTE with excitation temperatures of 1800-2300K • The detected H2 morphologies, kinematics and/or excitation exclude X-ray heating and stellar Ly pumping of a disk as the main excitation. • Spatial extent ~3+x too great for disk emission excited by central stellar flux • Measured excitation Temperatures too high for X-ray heating by central star at distances >50AU. • A component of UV Pumping and/or X-ray heating in the inner ~30AU environment cannot (and should not) be ruled out In all cases, the spatial distribution, excitation, and kinematics of the bulk of the H2 are consistent with shocks from the Herbig-Haro outflows and/or wide angle winds that exist around these stars not from quiescent gas in disks or disk gaps TBeck, AAS

  28. A Micro Molecular Bipolar outflow from HL Tau H2 and [Fe II] Emission from HL Tau • Fast (>100km/s) on-axis outflow in [Fe II] emission • H2 from HL Tau shows knots of emission offset to either side from the (fast) [Fe II] collimated outflow axis • Low velocity “wings” = Fast, on-axis outflow is accelerating surrounding material in a (micro) bipolar outflow (10-100 smaller scale than the known very extended CO molecular flows) Takami et al. 2007 TBeck, AAS

  29. Molecular Hydrogen Outflows Shock Excited H2 in a wide-angle molecular outflow accelerated by the on-axis gas ~200 AU Shock Excited H2 in the Inner, Wide-angle regions of the flow • Fast (>100km/s) on-axis outflow in [Fe II] emission • H2 can arise from inner wide angle component (e.g. DG Tau) • Low velocity “wings” = Fast, on-axis outflow is accelerate surrounding material in a (micro) bipolar outflow (10-100 smaller scale than the known very extended CO molecular flows - HL Tau) H2 Star Fast, Collimated on-Axis Flow Seen in [Fe II] H2 TBeck, AAS

  30. A New View of some Old Friends! YSOs in 3 “Colors” Red= H2, Green = Kcontinuum, Blue = [FeII] - Size of Pluto’s Orbit HL Tau HV Tau C For all but HV Tau C, Kcont is 1000’s of times brighter Haro 6-10 DG Tau N RW Aur E In most cases, H2 encompasses [Fe II] emission TBeck, AAS T Tau

  31. A Closer Look at one of My Favs! Haro 6-10 (GV Tau) with NIFS + LGS!! . TBeck, AAS

  32. A Closer Look at Haro 6-10 (GV Tau) • Haro 6-10 - 1.”2 Separation “Class I” Embedded YSO Binary • “Infrared Luminous Companion” System - The IR companion is optically undetected but has a higher Lbol (Leinert & Haas 1989) • NIFS LGS Queue Observations obtained in February 2007 • H and K-band settings • 2-point dither mosaic for a total field of ~3.”0 x ~4.”75 • LGS AO Corrected PSF - FWHM in combined cubes is ~0.”09 • “Longslit” Spectra North . FWHM ~0.”09 180 AU K-band Continuum Image South TBeck, AAS

  33. Haro 6-10 (GV Tau):NIFS LGS Observations of YSOs • Photospheric absorption in Southern star (K5 Spectral Type), high Av toward northern star • HI Emission traces accretion onto the central star, emission believed to arise within the inner ~5-10 stellar radii (we resolve ~3% of the Br flux to 100+ AU distances in the jet) • He I Emission (stellar wind) . 0.”8 width, ~1.”5 long Aperture, “longslit” spectrum TBeck, AAS

  34. Haro 6-10 (GV Tau):NIFS LGS Observations of YSOs • Spectra of YSO Jets… • H2 Emission traces warm gas, likely excited by shocks in outflows, We find 10 different transitions in K-band, 3 in H • [Fe II] emission traces shocked gas in dense regions of the outflows, We detect 7 different transitions . H2 TBeck, AAS [FeII]

  35. Molecular Hydrogen in Haro 6-10 • Map of v=1-0 S(1) H2 in the Haro 6-10 Environment • H2 is brighter toward the southern component • Strong H2 (S/N > 10) over ~85% of the field • Much of the H2 Shows a knots & arcs morphology structure seemingly typical of outflows/jet excitation TBeck, AAS

  36. Molecular Hydrogen Line Ratios: A Tracer of Extinction TA Brief reminder on H2 level populations • Ro-vibrational diagram of the first electronic level in the H2 molecule • Emission line ratios for transitions that arise from the same initial state (e.g., S(1) & Q(3) transitions, S(0) & Q(2): Ia = h a Aa N = b Aa Ib h b Ab N a Ab = CONSTANT for a given ratio (N= population of the upper state) Q(3) S(1) v=1-0 Q(3) / S(1) Ratio = 0.7 TBeck, AAS

  37. Molecular Hydrogen Line Ratios: A Tracer of Extinction Deviations from a line ratio = 0.7 are caused by phenomenon extrinsic to the emission environment Such as extinction, ISM extinction follows a A = Av*(/0.55)-1.6 Power law v=1-0 Q(3) / S(1) Ratio = 0.7 TBeck, AAS

  38. Molecular Hydrogen Line Ratios: A Tracer of Extinction The JOY of the IFU! 70% of the IFU field has Q(3) flux detected at S/N > 10 Plot the Q(3) vs. S(1) flux at every pixel location where H2 is detected TBeck, AAS

  39. Molecular Hydrogen Line Ratios: A Tracer of Extinction The JOY of the IFU! • Regions with similar line ratios are correlated in space (and across IFU pointings!) • On average, greater extinction is seen toward the Northern component • 40% of the IFU field has a (Q3)/S(1) line ratio that is >1 below the 0.7 limit! (color scale purple =0.1, red =1.8 in ratio) 4 3 1 2 TBeck, AAS

  40. 1.38 4 Molecular Hydrogen Line Ratios 0.42 4 3 3 0.85 1 1 0.41 2 2 TBeck, AAS

  41. Molecular Hydrogen Line Ratios: Why is the detected ratio LESS than 0.7?? • Historically, any Q(3)/S(1) line ratio that is below the 0.7 “limit” is assumed to be severely adversely affected by poor telluric correction in the Q(3) line flux • & Correction of the Q-branch region for telluric absorption dominates the uncertainty on the emission line ratios • BUT… This should correlate with detected flux level and be constant across the sky for regions with the same flux • Is there anything else besides extinction that could affect the emission line ratios? TBeck, AAS

  42. Molecular Hydrogen Line Ratios - The Answer? Classic NICMOS IR Images of Protostars - Padgett et al. 1999 0.85 Scattered Light into the line of sight! - The bane of everyone that studies embedded YSOs! TBeck, AAS

  43. As for YSO Imaging, Scattered light Affects H2 line Ratios 99.5% of All pixels with strong H2 detections have deviant ratios that can be explained by Rayleigh scattering and/or by ISM extinction with Av<40 TBeck, AAS

  44. Haro 6-10 (GV Tau):Velocity/Morphology of [Fe II] • Switching Wavelength regions to [Fe II] • H2 traces wide angle components of the outflows, [Fe II] arises in shocks within the flows themselves and traces the fast, on-axis gas in the collimated regions of the flows. • Velocity movie in 1.644m [FeII] Emission - I.e., stepping throught he datacube in wavelength, from -202km/s to +186km/s in steps of ~27km/s (1 pixel) . TBeck, AAS

  45. Haro 6-10 (GV Tau):Velocity/Morphology of [Fe II] 1.644m • Velocity movie in • 1.644mm [FeII] Emission • from -202km/s to +186km/s in steps of ~27km/s (1 pixel) • 2 Outflows in a sub-200AU YSO binary • Blueshifted outflow is associated with the SOUTHERN Component - Redshifted outlow is associated with the NORTHERN Component . TBeck, AAS

  46. Haro 6-10 (GV Tau):NIFS LGS Observations of YSOs 1.644 micron K-band Continuum 2.12micron H2 . Redshifted emission OUT FLOW CAVITY? Blueshifted emission JETS! STARS! TBeck, AAS

  47. Haro 6-10 (GV Tau):NIFS LGS Observations of YSOs . TBeck, AAS

  48. Haro 6-10 (GV Tau):NIFS LGS Observations of YSOs • Haro 6-10: • Mis-aligned outflows and evidence for non-coplanar circumstellar disks • Mis-aligned disks seen in high order multiples only (Jensen et al. 2004) • Explanations for mis-aligned outflows/disks in multiples (& the IRC phenomenon) evoke stellar interactions in YSO triple systems (Reipurth 2001) • Prior detection of two possible companions in the Haro 6-10 system… which we DON’T detect! . Dynamical Evolution in YSO Triples * Koresko (1999) * Reipurth et al. (2004) TBeck, AAS

  49. The Inner 200AU Environs of YSOs Revealed by Gemini NIFS • H2 emission detected in ro-vibrational transitions in the K-band is dominated by emission from the outflows, in many cases corresponding to a smaller angular scale counterpart to bi-polar molecular outflows • Perhaps unsurprisingly, analysis of H2 lines towards Haro 6-10 shows that scattered light can affect the ratios of lines that arise from the same upper state • The Embedded Haro 6-10 Binary shows evidence for mis-aligned outflows and disks (which is presently explained only for YSO triples) TBeck, AAS

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