VERY LARGE ARRAY OBSERVATIONS OF DG TAU'S RADIO JET: A HIGHLY COLLIMATED THERMAL OUTFLOW
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52240 (United States)
- Department of Astrophysics, University of Vienna, A-1180 Vienna (Austria)
- Astronomy and Astrophysics Section, Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland)
- Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States)
- Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg (Germany)
The active young protostar DG Tau has an extended jet that has been well studied at radio, optical, and X-ray wavelengths. We report sensitive new Very Large Array (VLA) full-polarization observations of the core and jet between 5 GHz and 8 GHz. Our high angular resolution observation at 8 GHz clearly shows an unpolarized inner jet with a size of 42 AU (0.''35) extending along a position angle similar to the optical-X ray outer jet. Using our nearly coeval 2012 VLA observations, we find a spectral index {alpha} = +0.46 {+-} 0.05, which combined with the lack of polarization is consistent with bremsstrahlung (free-free) emission, with no evidence for a non-thermal coronal component. By identifying the end of the radio jet as the optical depth unity surface, and calculating the resulting emission measure, we find that our radio results are in agreement with previous optical line studies of electron density and consequent mass-loss rate. We also detect a weak radio knot at 5 GHz located 7'' from the base of the jet, coincident with the inner radio knot detected by Rodriguez et al. in 2009 but at lower surface brightness. We interpret this as due to expansion of post-shock ionized gas in the three years between observations.
- OSTI ID:
- 22167558
- Journal Information:
- Astrophysical Journal, Vol. 766, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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