Volume 550, February 2013
|Number of page(s)||4|
|Published online||18 January 2013|
HST FUV C iv observations of the hot DG Tauri jet
Hamburger Sternwarte, Gojenbergsweg 112,
2 Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
3 Universität Wien, Dr.-Karl-Lueger-Ring 1, 1010 Wien, Austria
4 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
5 The Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Hai Dian Qu, 100871 Beijing, PR China
Received: 6 December 2011
Accepted: 14 December 2012
Protostellar jets are tightly connected to the accretion process and regulate the angular momentum balance of accreting star-disk systems. The DG Tau jet is one of the best-studied protostellar jets and contains plasma with temperatures ranging over three orders of magnitude within the innermost 50 AU of the jet. We present new Hubble Space Telescope (HST) far-ultraviolet (FUV) long-slit spectra spatially resolving the C iv emission (T ~ 105 K) from the jet for the first time, in addition to quasi-simultaneous HST observations of optical forbidden emission lines ([O i], [N ii], [S ii], and [O iii]) and fluorescent H2 lines. The C iv emission peaks at ≈ 42 AU from the stellar position and has a FWHM of ≈ 52 AU along the jet. Its deprojected velocity of around 200 km s-1 decreases monotonically away from the driving source. In addition, we compare our HST data with the X-ray emission from the DG Tau jet. We investigate the requirements to explain the data by an initially hot jet compared to local heating. Both scenarios indicate a mass loss by the T ~ 105 K jet of ~10-9 M⊙ yr-1, i.e., between the values for the lower temperature jet (T ≈ 104 K) and the hotter X-ray emitting part (T ≳ 106 K). However, a simple initially hot wind requires a large launching region (~1 AU), and we therefore favor local heating.
Key words: stars: winds, outflows / stars: pre-main sequence / ISM: jets and outflows / ultraviolet: stars / stars: individual: DG Tauri
© ESO, 2013
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