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

Poster 1K024

Cool, warm and hot outflows from CTTS: The FUV view of DG Tau

Schneider, Christian (Hamburger Sternwarte)
Eisloeffel, Jochen (Thueringer Landessternwarte)
Guedel, Manuel (University of Vienna)
Guenther, Moritz (Center for Astrophysics)
Herczeg, Greg (Peking University)
Robrade, Jan (Hamburger Sternwarte)
Schmitt, Juergen (Hamburger Sternwarte)

Abstract:
Classical T Tauri stars drive strong outflows with temperatures from about 1e3 K up to a few 1e6 K. These outflows regulate the angular momentum balance and are therefore tightly related to the accretion process. However, the outflow driving and heating mechanisms are not well understood. We present new HST data of the prototypical jet-driving CTTS DG Tau tracing the low-temperature outflow with far-UV molecular hydrogen emission and the high-temperature part with C IV emission. We find that the low-temperature part shows a pronounced V-shape consistent with molecular disk-wind models. Low-velocity shocks are probably the pumping source for the FUV H2 lines. The hot plasma (T>1e5 K) is located close to the jet axis at a distance of 40 AU from the driving source and spatially offset from usual (optical) jet-tracers like [S II] or [O I]. It does not show any hints for proper-motion contrasting typical jet properties. The high-temperature plasma is unlikely to be caused by a hot stellar wind and we propose that the stationary heating is due to internal shocks or magnetic reconnection.

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