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VLT Integral Field Spectroscopy of Embedded Protostars Near-IR emission lines as tracers of accretion and outflow Chris Davis Joint Astronomy Centre Hilo, Hawaii. IGRINS Workshop SNU, August 2010. OMC-2. WFCAM JHH2. HST/NICMOS. SVS13.

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slide1
VLT Integral Field Spectroscopy of

Embedded Protostars

Near-IR emission

lines as tracers of

accretion and

outflow

Chris Davis

Joint Astronomy Centre

Hilo, Hawaii

IGRINS Workshop

SNU, August 2010

OMC-2

WFCAM JHH2

why do spectroscopy of protostellar jet sources
HST/NICMOS

SVS13

Why do spectroscopy of protostellar jet sources…?

2.12/3.6/4.5m

Davis et al. 2008

Reipurth et al. 2000

slide3
HH sources

Early spectroscopic observations of embedded young stars - particularly (variable) outflow sources - reveal a wealth of emission lines….

FUors

Reipurth & Aspin, 1997

slide4
At about the same time…

High-spectral-resolution observations of T Tauri stars

Spatial & kinematic properties…

Continuum-subtracted Spectral Images

Hirth et. al, 1997

echelle spectroscopy at ukirt with cgs4 r 16 000 h 2 1 0s 1 @ 2 122 m
Echelle spectroscopy at UKIRT with CGS4

R ~ 16,000; H2 1-0S(1) @ 2.122 m

Davis et al. 2001

slide6
Spatial information from

Spectro-Astrometry

  • Fit Gausian
  • Measure position of
  • peak to within
  • Hundredths
  • of an arcscond
  • (10s of AU scales)

- position -

- velocity -

Profile along slit

in one velocity bin

(along one column)

slide7
45 AU

60 AU

60 AU

1500 AU

echelle spectroscopy at ukirt with cgs41
Echelle spectroscopy at UKIRT with CGS4

Davis et al 2003

Aha! A fast [FeII] jet with a slow H2 wind - a result!!.

slide10
Benefits of Integral Field Spectroscopy

2-Dimensional spectroscopy (3-D data cube)

Simultaneous imaging in multiple lines

Images taken with same weather conditions (seeing and cloud)

All images aligned on the sky (differential refraction found to be minimal)

Perfect “continuum-subtraction” possible - ideal for bright jet sources!!

slide11
Observed SEVEN HH energy sources

SINFONI on the ESO-VLT

1.1-2.45 m Integral Field Spectrometer

2048x2048 Hawaii 2RG array

32 slitlets, each is 64 pixels long and 2 pixels wide

0.05 arcsec pixels; 3.2 x 3.2 arcsec field of view

H+K grating used (R~1500; v ~ 200 km/s)

red br green h 2 blue feii contours continuum
HH 999-IRS

HH 34-IRS

HH 300-IRS

Red - Br, Green - H2, Blue - [FeII], Contours - continuum

SVS 13

HH 26-IRS

HH 72-IRS

slide13
red

Stepping

through

wavelength

(velocity)

( R ~ 1500, V ~ 200 km/s)

…can see red and blue lobes,

but not much else in these channel

maps

blue

  • Not continuum-subtracted
  • Each channel separated
  • by ~200 km/s (two pixels)
slide14
HH 34-IRS in [FeII]

1”

Insufficient

velocity

resolution!

though clearly there’s

important kinematic

information that we

are just missing…

Acceleration along jet?

Gradient across width of flow?

IGRINS!?

Each channel separated by ~100 km/s (one pixel)

slide15
Br

[FeII]

H2

70AU (0.32”)

Profiles along the jet axis

Full thick line - Br; Dashed thick - continuum

Full thin - H2; Dashed thin - [FeII]

Br coincident with source continuum position, except in closest source, HH 300-IRS;

offset by 0.026”(0.005”) = 3.6(0.7)AU

expansion of each flow component h 2 red feii blue collimated unresolved over first 100 200 au
H2

[FeII]

100 AU

100 AU

100 AU

Expansion of each flow component

H2 - red; [FeII] - blue …..Collimated (unresolved) over first 100-200 AU

[FeII]

H2

100 AU

100 AU

100 AU

H2 and [FeII] opening angles of order 20-40 degs over first 100-200 AU

slide17
H-band spectra

1.46-1.86 m

Forbidden [FeII]

Hydrogen recombination

Only see (veiled)

absorption lines from

most evolved source,

HH 83-IRS

0.5” aperture centre

on the source

slide18
K-band spectra

1.95-2.42 m

H2 and [FeII]

Nebula emission lines

Strong CO bandheads

Again, only see (veiled)

absorption lines from

most evolved source,

HH 83-IRS

0.5” aperture centre

on the source

hh 34 irs versus hh 83 irs young vs old
HH 34-IRS

versus

HH 83-IRS

(young vs old…)

R ~ 1500 just about makes the cut.

Higher spectral resolution would certainly result in better data!

correlation between emission lines 1
r = 0.98

P = 2%

Correlation between

emission lines - 1

r = 0.95

P = 6%

Apparent correlation between nebula

lines and high-density inner-disk

tracer, CO

r = 0.87

P = 8%

correlation between emission lines 2
r = 0.83

P = 21%

However, little or no correlation

between outflow tracers (H2 and

[FeII]) and CO

Is this a result of the H2/[FeII]

excitation mechanism, and the

short cooling times in the post-shock

gas (few years)?

Correlation between

emission lines - 2

r = 0.34

P = 59%

extinction towards the jet base 1
De-reddening J-H and H-K colours in a C-C diagram

Av= 10

Extinction towards the Jet Base - 1

J-H

TTS locus

H-K

extinction towards the jet base 2
HH 26-IRS (Av = 27)

H2 rotational diagrams

minimising scatter about

linear or second-order

polynomial fits

Extinction

towards the

Jet Base - 2

  • R2 - square of correlation coefficient
  • Vary Av - measure R2
  • (goodness of fit).
  • Best R2 gives Av
  • o/p =2.53; Tex= 2976 K
extinction towards the jet base 3
HI line ratios - case B recombination, but ratios only consistent with high densities (109-1010 cm-3) and low T (2,000K) - see also Bary et al. 2010
  • H2and [FeII] line ratios - but best if J and H-band [FeII] lines

Extinction towards the Jet Base - 3

  • Range in extinction values
  • No method is entirely satisfactory….
  • Measuring Av is a major issue when trying to probe and quantify the
  • physical conditions at the jet base (particularly for the more embedded
  • Class I sources)
extinction maps from h 2 and feii line ratios
Extinction maps from H2and [FeII] line ratios

Signs of decreasing extinction

along each jet axis…

(IGRINS - along the slit!)

slide26
Electron Density (and Temperature) from [FeII] line ratios

J-band needed to constrain Te

but

H band to constrain density, ne

(relatively insensitive to Te)

ne ~ 104 - 105 cm-3

Models + HH1 data; Nisini et al. (2005)

some conclusions

Some Conclusions…

Abundance of (bright) diagnostic lines produced at the base of (and along the length of) these HH jets

IFU spectroscopy - excellent tool for studying these regions

… but …

Long-slit spectroscopy with IGRINS would be extremely useful: velocity and excitation info along the flow (just don’t forget to align the slit with the jet axis!!)

some conclusions from our ifu data

Some Conclusions…(from our IFU data)

No obvious indication that [FeII] jet component is more collimated than the H2 component

However, high velocities accompanied by smaller opening angles

Extinction decreases rapidly along jet axis

Electron density decreases rapidly along jet axis

Need better spatial AND spectral resolution to properly test/constrain jet collimation and acceleration models.

slide32
Unbiased survey of the Inner Galactic Plane in the H2 1-0S(1) line at 2.122μm
  • Data obtained with WFCAM: sub-arcsec resolution; 800 sec/pixel; >18th mag
  • Complements UKIDSS Galactic-Plane JHK imaging
  • Covers 150 square degrees (10° < l < 65°, |b| ~ 1°) - GLIMPSE-N

Data acquired forl ~ 10 - 26°, |b| ~ 1.5° and l ~ 26 - 37°, |b| ~ 0.5°

http://astro.kent.ac.uk/uwish2/

slide33
1052 MHOs separated into 22 Tables (based on constellations)
  • Updated weekly online; first 1000 objects in CDS; handy Search tool !!!

http://www.jach.hawaii.edu/UKIRT/MHCat/

slide34
Simple ascii tables also available, for overplotting on other images/data-sets

http://www.jach.hawaii.edu/UKIRT/MHCat/

slide35
UWISH2

http://astro.kent.ac.uk/uwish2

(or Google “UWISH2”)

MHO Catalogue

http://ww.jach.hawaii.edu/UKIRT/MHCat

(or Google “MHO catalogue”)

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