HH s at NIR ObservationsDiagnosis

 NKL  Trapezium  OMC1-S (L = 10 5 L o t << 10 5 yr) (L = 10 4 L o, t < 10 5 yr) (L = 10 5 L o t < 10 5 yr ) OMC 1 Outflow   t = 500 yr) Orión Nebula Infrared “continuum “line”

1-0 S(1) H2H2

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

Nadeau&Geballe (1979), ApJL, 230 L169 Lines of H m m show FWHM kms -1  v g ~40 kms -1 (and up to 100 kms -1 )----->PROBLEM: Models found that shocks with v>25kms -1 disociate the H 2 molecule (Kwan 1977 ApJ, 216, 713)

Schwartz et al. (1987), ApJ, 322,403 The first observations (low- resolution spectroscopy) showed that the low-excitation HHs had strong H 2 emission The strongest H 2 emission line is at 2.12 m m Usually, the intesities of the H a and H 2 at2.12 m m emission lines have similar strengths. Usually, the intesities of the H a and H 2 at 2.12 m m emission lines have similar strengths.

HHs in NIR Emission lines of H 2  cooling of the shock in HHs  H 2 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  H 2 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) H 2 (~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: The optical counterpart of a NIR jet is detected far from the source than the NIR jet. I II Optical and NIR emissions are tracing different physical conditions  In general, is not possible to predict the NIR emission from the optical one. Comparing optical/nir emission:

Non-coincidence optical/NIR jets

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

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

Without optical counterpart

HH 212 Tedds et al. RmxAA 13,103 (2002 RmxAA 13,103 (2002)

HH 212 Wiseman, J. ApJ, 550, L87 (2001 ApJ, 550, L87 (2001) NH 3

Narrow-band NIR images: [FeII] (1.644) y H 2 (2.122) In general: *There is a complex relationship between the spatial distribution of both emissions. distribution of both emissions. *At the bow-shocks: + [FeII] : brighter at the apex : (v s ) n + [FeII] : brighter at the apex : (v s ) n has its maximum has its maximum +H 2 : brighter at the winds (v s ) n lower. +H 2 : brighter at the winds (v s ) n lower.

Davis et al MNRAS, 318, 747 Red: H 2 green: [FeII]

Excitation mechanisms for H 2 levels: a)Fluorescence: pumping UV photons b)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~ K T~ K

1-0 S(1) H2H2

H 2 emission lines in H and K bands observed in stellar jets

IR DIAGNOSTIC

HH46-47 jet at 2.12  m 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.

Continuum-subtracted spectra The presence of Br  emission near the source is signature of high excitation conditions in the region.

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

Kinematics: velocities of the ionized ([FeII] and neutral (H 2 ) emissions

Position-Velocity diagrams (Velocity, in LSR and corrected For a parental cloud velocity +20 km/s)

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.

Physical conditions

Temperature Using the H2 detected transitions  excitation diagrams: If collisional de-excitation is assumed to dominate, H 2 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 spectra Gredel, A&A,292,580 (1994) H K

The measured intensity, I(v,J), of a given H 2 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 K Dashed: Fit using the four lowest levels, T = 1900K T=T= T=2200K T=1900K

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

Density

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

[FeII] as a tracer of n e : * [FeII] as a tracer of n e : n c [Fe] >> n c [SII], [OII]  Use to derive n e in regions of n e > 10 4 cm -3 and/or with higher extinction. * As a tracer of T: Lines in the range  m arise from a level with four sublevels ~  E  line ratios are weakly dependent on T  a good choice is to combine lines from another range  ex: 8671 A m m * To derive the reddening: Lines in J and H windows, arising from the same sublevel:   The line ratio is sensitive to the reddening  (ex m m y m m)  A v F /F = 1.36x10 -(E J-H /2.5) A v = 10xE J-H

Ex: A combined optical/infrared spectral diagnostic of HH 1 (see Nisini et al.,2005, A&A,441, 159 for details).

Derived physical parameters along the HH 1 jet.