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ISO spectroscopy of shocked gas in the vicinity of T Tauri *
M.E. van den Ancker 1,
P.R. Wesselius 2,
A.G.G.M. Tielens 2,3,4,
E.F. van Dishoeck 5 and
L. Spinoglio 6
Received 26 May 1999 / Accepted 28 June 1999
We present the results of ISO SWS and LWS spectroscopy of the young binary system T Tau. The spectrum shows absorption features due to H2O ice, CO2 ice, gas-phase CO and amorphous silicate dust, which we attribute to the envelope of T Tau S. We derive an extinction of = towards this source. Detected emission lines from H I arise in the same region which is also responsible for the optical H I lines of T Tau N. These lines most likely arise in a partially ionized wind. Emission from the infrared fine-structure transitions of [S I ], [Ar II ], [Ne II ], [Fe II ], [Si II ], [O I ] and [C II ] was also detected, which we explain as arising in a 100 km s-1 dissociative shock in a fairly dense ( cm-3) medium. Pure rotational and ro-vibrational emission from molecular hydrogen was detected as well. We show the H2 emission lines to be due to two thermal components, of 440 and 1500 K respectively, which we attribute to emission from the dissociative shock also responsible for the atomic fine-structure lines and a much slower ( 35 km s-1) non-dissociative shock. The 1500 K component shows clear evidence for fluorescent UV excitation. Additionally, we found indications for the presence of a deeply embedded ( ) source of warm H2 emission. We suggest that this component might be due to a shock, caused by either the outflow from T Tau S or by the infall of matter on the circumstellar disk of T Tau S.
Key words: stars: circumstellar matter stars: individual: T Tau stars: pre-main sequence ISM: jets and outflows infrared: stars
* Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.
Send offprint requests to: M.E. van den Ancker (firstname.lastname@example.org)
Online publication: August 13, 199