Sub-arcsecond high sensitivity measurements of the DG~Tau jet with e-MERLIN

TL;DR

This study uses high-resolution e-MERLIN radio observations to analyze the collimation and launching region of the DG Tau A jet, providing detailed jet parameters that support MHD jet-launching models.

Contribution

First high-resolution radio measurements of DG Tau A's jet close to the star, revealing initial wide opening angles and detailed jet parameters.

Findings

Jet initially has an 86-degree opening angle within 2 au.

Mass-loss rate of 1.5x10^-8 solar masses/yr for the ionized jet component.

Ejection to accretion ratio ranges from 0.06 to 0.3.

Abstract

We present very high spatial resolution deep radio continuum observations at 5 GHz (6 cm) made with e-MERLIN of the young stars DG Tau A and B. Assuming it is launched very close (~=1 au) from the star, our results suggest that the DG Tau A outflow initially starts as a poorly focused wind and undergoes significant collimation further along the jet (~=50 au). We derive jet parameters for DG Tau A and find an initial jet opening angle of 86 degrees within 2 au of the source, a mass-loss rate of 1.5x10^-8 solar masses/yr for the ionised component of the jet, and the total ejection/accretion ratio to range from 0.06-0.3. These results are in line with predictions from MHD jet-launching theories.