The chemical inventory of HH1 Teresa Giannini, Brunella Nisini, Simone Antoniucci, Dario Lorenzetti, Juan Alcala’, Francesca Bacciotti, Sara Bonito, Linda Podio, Beate Stelzer

Observations HST Hα HH1 is one of the brightest HH- objects: a well suited laboratory to study chemical composition, abundances and physical conditions Deep X-shooter observations from UVB to NIR (~5 h) 11’ arcsec slit R ~10000 (UVB), (VIS), 8000 (NIR) Analysis A V determination Derivation of the physical conditions Derivation of the chemical abundances Ratios of Iron Einstein coefficients RA (J )

The spectrum : UVB and VIS More than 500 detections of atomic fine structure lines (more than 100 [FeII] lines) of atoms with Z up to 28, HI and HeI,II recombination lines, and H 2 ro-vibrational lines with v up  9. Likely the deepest spectrum of an HH object sofar observed. Solf+ (1988) detected less than 100 lines.

The spectrum : NIR

Accurate A V determination A V also determined from H 2 and atomic lines with the same method. A V between 0.0 mag and 0.8 mag Giannini et al. 2014

Physical conditions NLTE code to solve the statistical equilibrium equations for the fine structure levels of atoms (collisional excitation and de- excitation, spontaneous radiative decay) T e, n e Models for Fe II (159 levels), FeIII (34 levels), Ni II (17 levels), TiII (30 levels ), CI, NI, NII, OI, OII, OIII, NeII, PII, SII, SIII, ArIII, ArIV, CaII, CrII (5 levels) Ionization equilibrium solved for species observed in different ionization stages (e.g. O, S, N). Considered processes: collisional ionization, radiative and dielectronic recombination, charge exchange x e = n e /n H

Diagnostic diagrams: T e, n e Temperature indicators Density indicators

Diagnostic diagrams: T e, n e Simultaneous determination of T e,n e

Diagnostic diagrams : T e, n e Best fit through the [FeII] lines. In red are data from levels whose atomic parameters (collisional and radiative) are uncertain. Summarizing : K  T e  K, 10 3 cm -3  n e  cm -3

Diagnostic diagrams : x e 0.55  X e  1

Physical conditions : T e, x e vs IP ave Good correlation between temperature and degree of ionization up to ~ K ()

Chemical abundances Abundances lower than solar Depletion of refractory species around 50% ZSolarOrion nebula HH1 Sun- HH1 Orion- HH1 C8.39 (0.05) N7.78 (0.06) (0.05) P5.36 (0.04) S7.14 (0.05) Cl5.50 (0.30) Ar6.18 (0.08) Ca6.31 (0.04) Ti4.90 (0.06) Fe7.45 (0.05) Ni6.23 (0.04) Solar : Asplund Orion: Esteban Abundances computed taking into account the derived physical conditions, fractional ionization (x e ) and ionization equilibrium of species. Abundances computed with respect to H  if T K.

Iron Einstein coefficients Giannini (GAN) Fe + Einstein coefficients very difficult to be theoretically evaluated because of the complexity of the Iron level system. In HH1 some lines are detected with an exceptionally high SNR (>> 100) that allows to empirically derive the A-values RatioNSQ-SSTQ-HFRDBSHGAN 1.25  m/ 1.64  m (0.04) 1.32  m/ 1.64  m (0.01) NS:Nussbaumer & Storey 1988, Q-SST, Q-HFR: Quinet+ 1996, DB: Debb & Hibbert 2011, SH: Smith & Hartigan 2006 Our determinations better agree with a large set of observations F 1.32/ F 1.64 F 1.25/ F 1.64

The H 2 emission H 2 ro-vibrational lines with v up  9 (more than 200 lines in the VIS and NIR arm) Rotational diagrams of lines with SNR > 5 Lines fitted with 2 temperature components at T ~ 3000 K and T ~ 6000 K (although with deviations from LTE) Fluorescence is not the main excitation mechanism (model from Stenberg & Dalgarno 1989) C-ontinous type shocks do not predict bright high v up lines Most probable exciting mechanism is a J-ump shock (with or without a magnetic precursor) Log

Conclusions X-shooter observations have provided the deepest UVB – NIR spectrum of an HH object with the detection of hundreds of lines from several atomic species. We are able to determine very precisely the conditions of the emitting gas, which reveal a stratification in temperature, density, and fractional ionization. Temperatures as high as K are revealed. Chemical abundances are estimated for a number of species deriving values lower than the solar ones and a level of depletion of the refractory species around 50 %. Empirical determinations of the Einstein A-ratios for important [FeII] lines are derived.