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

The Inner 200AU Environs of The Inner 200AU Environs of Classical T Tauri Stars Classical T Tauri Stars

Revealed by Gemini NIFSRevealed by Gemini NIFS

Tracy L. Beck (STScI & Gemini Observatory)Tracy L. Beck (STScI & Gemini Observatory)Peter J. McGregor (Australian National University)Peter J. McGregor (Australian National University)

Michihiro Takami (ASIAA, Taiwan & Subaru Michihiro Takami (ASIAA, Taiwan & Subaru Observatory)Observatory)

04/19/23 TBeck, AAS

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

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Where Does H2 Arise From in YSO Environments?

H2 From Quiescent emission in a Disk (or disk gap)

H2 Fluorescently pumped by stellar UV/Ly flux or heated by UV/Xrays

H2 From Shocks in Outflows

H2 Excited into LTE emission by shocks

star

Circumstellar Dust DiskDisk gap cleared by

forming planets?

Circumstellar Disk

star

Outflow

30-50 AU

Bow Shock

10’s

, eve

n 1

00’s

of

AU

H2

H2 H2

H2

H2

H2

H2

H2

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H2 in the Inner 200 AU Environs of CTTSs’

• UV/IR Observations suggest moderate amounts of H2 emission excited by Lypumping,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.

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H2 Lines Detected in the IR K-band (2.0-2.45 m)

• 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

TA Brief reminder on H2 level populations

V=1-0 Q(3) & S(1)

V=2-1 S(1)

HH22 in the inner regions of YSOs in the inner regions of YSOs

• Virtually EVERY wavelength regime used for the study of H2 emission starts out with:

T TAU!T TAU!

Eponymous T Tauri, sub arcsec triple systemEponymous 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)

AO Studies of IR HAO Studies of IR H22 in Inner (<1”) YSO in Inner (<1”) YSO Environments…Environments…

• v=1-0 S(1) transition at 2.12m 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 2.12m emission near the T Tau South binary

2.12m H2 emission

Resolved Near IR HResolved Near IR H22 in Inner YSO in Inner YSO Environments…Environments…

• v=1-0 S(1) transition at 2.12m 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

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A New Tool For Studying YSO Jets: A New Tool For Studying YSO Jets: Integral Field Spectroscopy!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.

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Integral Field Spectroscopy: The Age of the Integral Field Spectroscopy: The Age of the IFU at 8-10m Observatories!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

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Integral Field Spectroscopy: The Age of the Integral Field Spectroscopy: The Age of the IFU at 8-10m Observatories!IFU at 8-10m Observatories!

Lenslets,

OSIRIS (Keck)

Lenslets+ fibres

GMOS (Gemini) VIMOS (VLT)

ImageSlicer

GNIRS, NIFS (Gemini), SPIFFI+SINFONI (VLT)

Telescopefocus

Spectrographinput

Spectrographoutput

Pupilimagery

Fibres

Mirrors

slit

slit

1 2 3 4

1

2

3

4

x

y

Datacube

Figure courtesy of J. Allington-Smith (U. of Durham)

3”

3”

NIFS

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Most of you HAVE heard of NIFS…Most of you HAVE heard of NIFS…

NIFS: A Remarkable Recovery!

Total DestructionJanuary 18, 2003

First Light!October 19, 2005

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The Near Infrared Integral Field Spectrograph The Near Infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory(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)

3”

3”

R~5000

NIFS

0.”040.”10

Individual Pixel Size

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The Near Infrared Integral Field Spectrograph The Near Infrared Integral Field Spectrograph (NIFS) at Gemini North Observatory(NIFS) at Gemini North Observatory

– 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”

3”R~50

00

NIFS

NIFS raw image

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NIFS Data Format, 29 Spectra in One NIFS Data Format, 29 Spectra in One

• NIFS H-band IFU Spectra of the young star, DG Tau

[Fe II] in DG Tau

NIFS K-band Observations of YSOs

• Data acquired in standard K-band setting for R~5000 spectra from 2.00 to 2.44m 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 HMost sources were known to have H2 2 emission, all are known HH emission, all are known HH

outflow starsoutflow stars

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2.12 micron Continuum Emission/2.12 micron Continuum Emission/ 2.12 2.12 micron Hmicron H22 Emission Emission

ContinuumBeck et al. 2008

FWHM=0.”12

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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

Continuum & H2

Spatially Extended H2 detected in ALL stars, and most is not coincident with continuum emission

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• 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

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In addition to In addition to vv=1-0S(1) at 2.12 =1-0S(1) at 2.12 m:m: Detection of Detection of

Multiple HMultiple H22features in ALL starsfeatures in ALL stars!!

HV Tau C: Nine v=1-0 and v=2-1 H2 features detected

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In addition to In addition to vv=1-0S(1) at 2.12 =1-0S(1) at 2.12 m:m: Detection of Detection of

Multiple HMultiple H22features in ALL starsfeatures 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)

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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 Morphology is important, but it is difficult in some cases to determine where the Hdetermine where the H2 2 is coming from solely based morphologyis coming from solely based morphology

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H2 Morphologies

HH22 in RW Aur clearly traces the known HH Outflow. DG Tau’s H in RW Aur clearly traces the known HH Outflow. DG Tau’s H22

encompasses the known blueshifted flow - a wide angle outflow encompasses the known blueshifted flow - a wide angle outflow component? component?

More Difficult

DG Tau RW Aur

Not so Difficult

1”

H2 Follows low velocity

[SII] emission almost

precisely

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HH22 Excitation Temperatures

In our obs. H2 Level Populations are best explained by populations in LTE with Tex ~1800K - 2300K

(=2-1 S(1) (2.24m) / =1-0 S(1) (2.12m) Ratio ).05-0.1)

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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).

HH22 emission that is shifted in velocity from the stellar RV is emission that is shifted in velocity from the stellar RV is shock excited in an outflow.shock excited in an outflow.

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

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Spatially Resolved Near IR HSpatially Resolved Near IR H22 Emission in the Emission in the Inner 200 AU of Classical T TaurisInner 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 In all cases, the spatial distribution, excitation, and kinematics of the bulk of the Hthe bulk of the H22 are consistent with shocks from the Herbig-Haro are consistent with shocks from the Herbig-Haro

outflows and/or wide angle winds that exist around these stars not from outflows and/or wide angle winds that exist around these stars not from quiescent gas in disks or disk gapsquiescent gas in disks or disk gaps

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A Micro Molecular Bipolar outflow 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

H2 and [Fe II] Emission from HL Tau

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Molecular Hydrogen Outflows

• 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)

Star Fast, Collimated on-Axis Flow Seen in [Fe II]

Shock Excited H2 in the Inner, Wide-angle

regions of the flow

Shock

Excited

H2 in a wide-angle molecular

outflow accelerated by the on-axis gas

H2

H2

~200 AU

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A New View of some Old Friends! A New View of some Old Friends! YSOs YSOs in 3 “Colors”in 3 “Colors”

HV Tau C

DG Tau

T Tau

RW Aur

Haro 6-10

- Size of

Pluto’s Orbit

Red= HRed= H22, , Green = KcontinuumGreen = Kcontinuum, , Blue = [FeII]Blue = [FeII]

HL Tau

For all but HV Tau C, Kcont is 1000’s of times brighter

N

E In most cases, H2 encompasses [Fe II] emission

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A Closer Look A Closer Look at one of My at one of My Favs! Favs! Haro 6-10 Haro 6-10

(GV Tau)(GV Tau).

with NIFS +

LGS!!

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A Closer Look at Haro 6-10 A Closer Look at Haro 6-10 (GV Tau)(GV Tau)

.

K-band Continuum

Image

180

AU

• 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

FWHM ~0.”09

North

South

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Haro 6-10 (GV Tau):Haro 6-10 (GV Tau): NIFS LGS Observations of YSOsNIFS 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

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.

• 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

[FeII]H2

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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

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Molecular Hydrogen Line Ratios: A Tracer of Extinction

• 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)

TA Brief reminder on H2 level populations

v=1-0 Q(3) / S(1) Ratio = 0.7

Q(3) S(1)

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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

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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

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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)

1

3

4

2

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Molecular Hydrogen Line Ratios

1

3

4

2

1

3

4

2

1.38

0.85

0.42

0.41

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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?

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Molecular Hydrogen Line Ratios - The Answer?

0.85

Scattered Light into the line of sight! - The bane of everyone that studies embedded YSOs!

Classic NICMOS IR Images of Protostars - Padgett et al. 1999

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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

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Haro 6-10 (GV Tau):Haro 6-10 (GV Tau): Velocity/Morphology of [Fe II]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 1.644m [FeII] Emission - I.e., stepping throught he datacube in wavelength, from -202km/s to +186km/s in steps of ~27km/s (1 pixel)

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Haro 6-10 (GV Tau):Haro 6-10 (GV Tau): Velocity/Morphology of [Fe II]Velocity/Morphology of [Fe II]

. Velocity movie in1.644mm [FeII] Emissionfrom -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

1.644m

QuickTime™ and aYUV420 codec decompressorare needed to see this picture.

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.K-band Continuum 2.12micron H21.644 micron

Redshifted emission

Blueshifted emissionJETS! STARS!

OUTFLOW CAVITY?

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.

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.

• 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

* Reipurth et al. (2004)

* Koresko (1999)

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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)

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

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