HST FUV C iv observations of the hot DG Tauri jet
Abstract
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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 2013
- DOI:
- 10.1051/0004-6361/201118592
- arXiv:
- arXiv:1212.6363
- Bibcode:
- 2013A&A...550L...1S
- Keywords:
-
- stars: winds;
- outflows;
- stars: pre-main sequence;
- ISM: jets and outflows;
- ultraviolet: stars;
- stars: individual: DG Tauri;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 5 pages, 2 figures, accepted by A&