Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 1K057

The diagnostic capability of iron limes

Giannini, Teresa (INAF-OAR, Italy)
Nisini, Brunella (INAF-OAR, Italy)
Antoniucci, Simone (INAF-OAR, Monte Porzio, Italy)
Alcala, Juan (INAF-OAC, Napoli, Italy)
Bacciotti, Francesca (INAF-OAA, Arcetri, Italy)
Bonito, Rosaria (INAF-OAP, Palermo,Italy)
Podio, Linda (Institut de Planetologie et d\' Astrophysique de Grenoble, France)
Stelzer, Beate (INAF-OAP, Palermo,Italy)
Whelan, Emma (Institut fur Astronomie, Tubingen, Germany)

We present the VLT/X-Shooter spectrum of two jets from young protostars of different luminosity and mass, ESO-Halpha 574 and Par-Lup 3-4. In the covered spectral range (350-2500 nm) we detected more than 100 [FeII] and [FeIII] lines, which are used to precisely probe the key physical parameters of the gas (electron density and temperature, ionization degree, visual extinction). These quantities have been compared with shock-model predictions, which suggest that only the higher luminosity source (ESO-Ha 574) is able to drive a high-velocity and dissociative shock. The diagnostic capability of Iron, proven on the presented objects, represents a unique tool for the following reasons: 1) the large number of lines in the uv-infrared range makes possible to trace the physical conditions in a very large range of the parameter space; 2) at variance with the diagnostic commonly performed with other species, such as Oxygen, Nitrogen, and Sulphur, no assumption on the relative abundance is needed, since all the parameters are derived from line ratios of the same species; 3) in the unperturbed ISM, Iron is locked on the grain surfaces, while it is released in gas-phase if gas-grain or grain-grain collisions occur within a shock. Therefore the Iron abundance (derivable from ratios of Iron lines with those of other volatile species) is a direct probe of the presence of dust in the jet beam, an information crucial to understand whether jets originate close to the star or in the circumstellar disk.

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