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HH s at NIR Observations Diagnosis. OMC 1 Outflow   t = 500 yr). Orión Nebula.  NKL.  Trapezium. (L = 10 5 L o t << 10 5 yr). (L = 10 5 L o t < 10 5 yr ).  OMC1-S. (L = 10 4 L o , t < 10 5 yr). Infrared. “ continuum. “line”. H 2. 1-0 S(1).

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Hh s at nir observations diagnosis

HHsat NIR

Observations

Diagnosis


Hh s at nir observations diagnosis

OMC 1

Outflow



t = 500 yr)

Orión Nebula

NKL

Trapezium

(L = 105 Lo

t << 105 yr)

(L = 105 Lo

t < 105 yr)

OMC1-S

(L = 104 Lo ,

t < 105 yr)

Infrared

“continuum

“line”


Hh s at nir observations diagnosis

H2

1-0 S(1)


Hh s at nir observations diagnosis

Gautier et al. (1976), ApJL, 209 L129:

The spectrum of the infrared nebula Beckling-Neugebauer (BN) of Orión:

From the analysis of H2 molecular gas at T~2000K


Hh s at nir observations diagnosis

Nadeau&Geballe (1979), ApJL, 230 L169

Lines of H2 2.12mm show FWHM 20-60 kms-1 vg~40 kms-1 (and up to 100 kms-1)----->PROBLEM: Models found that shocks with v>25kms-1 disociate the H2 molecule (Kwan 1977 ApJ, 216, 713)


Hh s at nir observations diagnosis

Schwartz et al. (1987), ApJ, 322,403

The first observations (low-resolution spectroscopy) showed that the low-excitation HHs had strong H2 emission

The strongest H2 emission line is at 2.12mm

Usually, the intesities of the Ha and H2 at2.12mm emission lines have similar strengths.


Hh s at nir observations diagnosis

HHs in NIR

Emission lines of H2 cooling of the shock in HHs  H2 emission clues on the physic in the low-velocity regime; “complementary” information from the one obtained from atomic line emission at optical wavelengths.

Because its characteristic cooling time is shorter  H2 emission lines trace the regions where the jet/ambient interaction is more recent than the regions traced by optical lines ( younger jets).

Also, we can trace the jet closer to the exciting source (as in Ha)

HH emission lines at NIR:

[FeII] (~1.64 mm) (H)

H2 (~2.12 mm) (K)


Hh s at nir observations diagnosis

Comparing optical/nir emission:

I

In few cases, the NIR “nebulosities” are the counterparts of HH wellkown jets. However the optical and nir emissions are not fully coincident (there is someshift).

II

Other NIR jets have not optical counterpart:

The optical counterpart of a NIR jet is detected far from the source

than the NIR jet.

Optical and NIR emissions are tracing different physical conditions

In general, is not possible to predict the NIR emission from the optical one.






Hh s at nir observations diagnosis

HH 212

Tedds et al.

RmxAA 13,103 (2002)


Hh s at nir observations diagnosis

HH 212

NH3

Wiseman, J.

ApJ, 550, L87 (2001)


Hh s at nir observations diagnosis

Narrow-band NIR images: [FeII] (1.644) y H2 (2.122)

In general:

*There is a complex relationship between the spatial

distribution of both emissions.

*At the bow-shocks:

+ [FeII] : brighter at the apex : (vs)n

has its maximum

+H2: brighter at the winds (vs)n lower.


Hh s at nir observations diagnosis

Davis et al. 2000

MNRAS, 318, 747

Red: H2

green: [FeII]


Hh s at nir observations diagnosis

  • Excitation mechanisms for H2 levels:

  • Fluorescence: pumping UV photons

  • Collisional excitation by shocks

  • Fluorescence: not clear evidence in HHs.

  • Collisional excitation: From intermediate-resolution HHs spectra  the obtained population distribution is consistent with a gas

  • T~ 2000-3000 K


Hh s at nir observations diagnosis

H2

1-0 S(1)


Hh s at nir observations diagnosis

H2 emission lines in H and K bands observed in stellar jets



Hh s at nir observations diagnosis

HH46-47 jet at 2.12 mm

Source: Class I, in a phase of high accretion; binary system

d~450pc; located at the border of a Bok globule.

Atomic and molecular flows associated.


Hh s at nir observations diagnosis

Continuum-subtracted spectra

The presence of Brg emission near the source is signature of high excitation

conditions in the region.




Hh s at nir observations diagnosis

Position-Velocity diagrams

(Velocity, in LSR and corrected

For a parental cloud velocity

+20 km/s)


Hh s at nir observations diagnosis

Radial velocitues computed by a Gaussian-fit to the line profile of each knot

Blue and redshifted values, decreasing as the distance to the source increases

Two velocity components in some knots.


Hh s at nir observations diagnosis

Physical conditions profile of each knot


Hh s at nir observations diagnosis

Temperature profile of each knot

Using the H2 detected transitions  excitation diagrams:

If collisional de-excitation is assumed to dominate, H2 population levelswill be in LTE Boltzmann distribution:

Ni/Nj = gi/gj exp [-(Ei – Ej)/kTex] N: column density ~ F line

Plot ln[N(n,J)/gn,J] vs E(n,J) linear fit slope ~ T-1

gn,J : statistical weight of a given (gn,J) ro-vibrational level

E(n,J): Excitation energy


Hh s at nir observations diagnosis

Ex: physical conditions HH 43 from NIR spectra profile of each knot

Gredel, A&A,292,580 (1994)

H

K


Hh s at nir observations diagnosis

T=2200K profile of each knot

T=

T=1900K

The measured intensity, I(v,J) , of a given H2 line is used to calculate the column density, N(v,J), of the upper excitation level of the transition. For optically thin emission,

I(v,J)=(h/4p) nA(v,J)N(v,J)

Plot of ln(N(v,J) vs excitation energy E(v,J):

Continuum: fit for T = 2200 K

Dashed: Fit using the four lowest levels, T = 1900K


Hh s at nir observations diagnosis

Temperature in a bow-shock (of HH99B) profile of each knot

Giannini et al., 2008, A&A,481,123


Hh s at nir observations diagnosis

Density profile of each knot


Hh s at nir observations diagnosis

[FeII] NIR emission profile of each knot

[FeII] shows a rich line spectrum

in the J-K wavelength range

(1.1-2.5 mm), very useful for the

analysis of the ionized component in

shocks produced in regions with high

optical extinction.


Hh s at nir observations diagnosis

* profile of each knot[FeII] as a tracer of ne :

nc [Fe] >> nc [SII], [OII] 

Use to derive ne in regions of ne > 104 cm-3 and/or with higher extinction.

*As a tracer of T:

Lines in the range 1.1-2.5 mm arise from a level with four sublevels ~

DE line ratios are weakly dependent on T 

a good choice is to combine lines from another range ex: 8671 A + 1.64 mm

  • *To derive the reddening:

  • Lines in J and H windows, arising from the same sublevel:

  • The line ratio is sensitive to the reddening

  • (ex. 1.257 mm y 1.644 mm) Av

  • F 1.257/F 1.644 = 1.36x10-(EJ-H/2.5)

  • Av = 10xEJ-H


Hh s at nir observations diagnosis

Ex: A combined optical/infrared spectral diagnostic profile of each knot

of HH 1

(see Nisini et al. ,2005, A&A ,441, 159 for details).