1999A&A...348..877V

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 A_V=17.4mag±0.6mag towards this source. Detected emission lines from HI arise in the same region which is also responsible for the optical HI lines of T Tau N. These lines most likely arise in a partially ionized wind. Emission from the infrared fine-structure transitions of [SI], [ArII], [NeII], [FeII], [SiII], [OI] and [CII] was also detected, which we explain as arising in a ≃100km/s dissociative shock in a fairly dense (5x10⁴cm^–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 1500K 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) non-dissociative shock. The 1500K component shows clear evidence for fluorescent UV excitation. Additionally, we found indications for the presence of a deeply embedded (A_V>40^m) 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.