ssat NIRat NIR

ObservationsObservations

DiagnosisDiagnosis

NKLTrapezium

OMC1-S

(L = 105 Lo

t << 105 yr)

(L = 104 Lo ,

t < 105 yr)

(L = 105 Lo

t < 105 yr )

OMC 1 Outflow

t = 500 yr)

Orión NebulaOrión Nebula

Infrared

“continuum “line”

1-0 S(1)1-0 S(1)

Gautier et al. (1976), ApJL, 209 L129:Gautier et al. (1976), ApJL, 209 L129:The spectrum of the infrared nebula Beckling-Neugebauer (BN) of Orión:The spectrum of the infrared nebula Beckling-Neugebauer (BN) of Orión:From the analysis of HFrom the analysis of H2 2 molecular gas at T~2000Kmolecular gas at T~2000K

Nadeau&Geballe (1979), ApJL, 230 L169Nadeau&Geballe (1979), ApJL, 230 L169Lines of HLines of H22 2.12 2.12m show FWHM 20-60 kmsm show FWHM 20-60 kms-1-1 v vgg~40 kms~40 kms-1-1 (and up to 100 (and up to 100

kmskms-1-1)----->)----->PROBLEM:PROBLEM: Models found that shocks with v>25kms Models found that shocks with v>25kms-1-1 disociate the Hdisociate the H22 molecule (Kwan 1977 ApJ, 216, 713) molecule (Kwan 1977 ApJ, 216, 713)

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

The first observations (low-The first observations (low-resolution spectroscopy) resolution spectroscopy) showed that the low-excitation showed that the low-excitation HHs had strong HHHs had strong H2 2 emissionemission

The strongest The strongest HH2 2 emission emission

line is at 2.12line is at 2.12mm

Usually, the intesities of Usually, the intesities of the Hthe Hand Hand H2 2 atat 2.122.12m m

emission lines have similar emission lines have similar strengths.strengths.

HHs in NIRHHs 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).

HH emission lines at NIR:[FeII] (~1.64 m) (H) H2 (~2.12 m) (K)

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

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 some shift).

Other NIR jets have not optical counterpart:Other NIR jets have not optical counterpart:The optical counterpart of a NIR jet is detected far from the sourceThe optical counterpart of a NIR jet is detected far from the sourcethan the NIR jet.than the NIR jet.

I

II

Optical and NIR emissions are tracing different physical conditionsOptical and NIR emissions are tracing different physical conditionsIn general, is not possible to predict the NIR emission from the optical one.In general, is not possible to predict the NIR emission from the optical one.

Comparing optical/nir emission:Comparing optical/nir emission:

Non-coincidence optical/NIR jetsNon-coincidence optical/NIR jets

Reipurth & Bally (2001), ARAA, 39, 403Reipurth & Bally (2001), ARAA, 39, 403

Noriega-Crespo et al., 1996, ApJ, 462,804Noriega-Crespo et al., 1996, ApJ, 462,804

Without optical counterpartWithout optical counterpart

HH 212HH 212

Tedds et al.Tedds et al.RmxAA 13,103 (2002RmxAA 13,103 (2002)

HH 212HH 212

Wiseman, J.Wiseman, J.ApJ, 550, L87 (2001ApJ, 550, L87 (2001)

NHNH33

Narrow-band NIR images: [FeII] (1.644) y HNarrow-band NIR images: [FeII] (1.644) y H2 2 (2.122)(2.122)

In general:In general:*There is a complex relationship between the spatial *There is a complex relationship between the spatial distribution of both emissions. distribution of both emissions.

*At the bow-shocks: *At the bow-shocks: + [FeII] : brighter at the apex : (v+ [FeII] : brighter at the apex : (vss))n n

has its maximumhas its maximum

+H+H22: brighter at the winds (v: brighter at the winds (vss))n n lower.lower.

Davis et al. 2000Davis et al. 2000MNRAS, 318, 747MNRAS, 318, 747

Red: H2

green: [FeII]

Excitation mechanisms for HExcitation mechanisms for H2 2 levels:levels:

a)a) Fluorescence: pumping UV photonsFluorescence: pumping UV photonsb)b) Collisional excitation by shocks Collisional excitation by shocks

Fluorescence: not clear evidence in HHs.Fluorescence: not clear evidence in HHs.

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

T~ 2000-3000 KT~ 2000-3000 K

1-0 S(1)1-0 S(1)

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

IR DIAGNOSTICIR DIAGNOSTIC

HH46-47 jet at 2.12 m

Source: Class I, in a phase of high accretion; binary systemSource: Class I, in a phase of high accretion; binary systemd~450pc; located at the border of a Bok globule.d~450pc; located at the border of a Bok globule.Atomic and molecular flows associated.Atomic and molecular flows associated.

Continuum-subtracted spectraContinuum-subtracted spectra

The presence of BrThe presence of Br emission near the source is signature of high excitation emission near the source is signature of high excitation conditions in the region.conditions in the region.

Spectrum for knot Z1 covering the J,H,K bandsSpectrum for knot Z1 covering the J,H,K bands

Kinematics: velocities of the ionized ([FeII] and neutral (HKinematics: velocities of the ionized ([FeII] and neutral (H22) )

emissionsemissions

Position-Velocity diagramsPosition-Velocity diagrams

(Velocity, in LSR and correctedFor a parental cloud velocity+20 km/s)

Radial velocitues computed by a Gaussian-fit to the line profile of each knotBlue and redshifted values, decreasing as the distance to the source increasesTwo velocity components in some knots.

Physical conditions

TemperatureTemperature

Using the H2 detected transitions excitation diagrams:If collisional de-excitation is assumed to dominate, H2 population levels

will be in LTE Boltzmann distribution:Ni/Nj = gi/gj exp [-(Ei – Ej)/kTex] N: column density ~ F line

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

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

E(,J): Excitation energy

Ex: physical conditions HH 43 from NIR spectraEx: physical conditions HH 43 from NIR spectra Gredel, A&A,292,580 (1994)

H

K

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/4)A(v,J)N(v,J)Plot of ln(N(v,J) vs excitation energy E(v,J):Continuum: fit for T = 2200 KDashed: Fit using the four lowest levels, T = 1900K

T=

T=2200K

T=1900K

Temperature in a bow-shock (of HH99B)Temperature in a bow-shock (of HH99B) Giannini et al., 2008, A&A,481,123

DensityDensity

[FeII] NIR emission[FeII] NIR emission

[FeII] shows a rich line spectrum [FeII] shows a rich line spectrum in the J-K wavelength range in the J-K wavelength range (1.1-2.5 (1.1-2.5 m), very useful for the m), very useful for the analysis of the ionized component in analysis of the ionized component in shocks produced in regions with high shocks produced in regions with high optical extinctionoptical extinction..

[FeII] as a tracer of n[FeII] as a tracer of ne e :: nncc [Fe] >> n [Fe] >> ncc [SII], [OII] [SII], [OII]

Use to derive nUse to derive nee in regions of n in regions of nee > 10 > 1044 cm cm-3 -3 and/or with higher and/or with higher

extinction.extinction.

As a tracer of T:As a tracer of T: Lines in the range 1.1-2.5 Lines in the range 1.1-2.5 m arise from a level with four sublevels ~ m arise from a level with four sublevels ~ EE line ratios are weakly dependent on T line ratios are weakly dependent on T a good choice is to combine lines from another range a good choice is to combine lines from another range ex: 8671 A + 1.64 ex: 8671 A + 1.64 m m

To derive the reddening:To derive the reddening:Lines in J and H windows, arising from the same sublevel: Lines in J and H windows, arising from the same sublevel: The line ratio is sensitive to the reddening(ex. 1.257 m y 1.644 m) Av

F 1.257/F 1.644 = 1.36x10-(EJ-H

/2.5)

Av = 10xEJ-H

Ex: A combined optical/infrared spectral diagnosticEx: A combined optical/infrared spectral diagnosticof HH 1 of HH 1

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

Derived physical parameters along the HH 1 jet.