2024A&A...687A..54S

Context. Young stars accrete matter from their surrounding protoplanetary disk and drive powerful outflows. These two processes shape the final system architecture, and studying how these processes interact is the goal of the ESO Large programme PENELLOPE. PENELLOPE complements the ULLYSES legacy programme on the Hubble Space Telescope (HST) by providing ground-based - Very Large Telescope (VLT) - optical and near-infrared spectroscopy of more than 80 low-mass young stars.
Aims. The main goal of this study is to screen the PENELLOPE/UVES targets for outflow activity and find microjets. A spectro-astrometric analysis in the [OI]λ6300 line in the velocity components of the microjet can give insights into the origin of the line emission, that is, if they originate from a magneto-hydrodynamical (MHD) wind or a photoevaporative wind.
Methods. In total, 34 T Tauri stars of the PENELLOPE survey have been observed with the high-resolution optical slit spectrograph UVES (R ∼ 65 000, λ = 3300-6800 Å). We formulated four criteria to rank the targets according to their outflow activity. Most of the targets have been observed in three different slit positions rotated by 120° with UVES. Using spectro-astrometric techniques in the [OI]λ6300 and Hα emission lines in each slit position of each target, we searched for outflow signatures, that is, an offset emission with respect to the continuum contribution of the associated T Tauri star. We checked all spectra for the presence of other wind line emission of [SII]λ4068, [SII]λ4076, [OI]λ5577, [OI]λ6300, [OI]λ6363, [SII]λ6716, [SII]λ6731, [NII]λ6548, and [NII]λ6583. Line profiles of Hα were inspected for a P Cygni signature. All [OI]λ6300 line profiles were decomposed into their constituent high-velocity component (HVC) and low-velocity component (LVC).
Results. Our spectro-astrometric analysis in the [OI]λ6300 wind line reveals two newly discovered microjets associated with Sz 103 and XX Cha. Both microjets have an extent of about 0″.04, that is, <10 au, and we confined their orientation by the three slit observations. We identified two other interesting targets for which all four outflow criteria are fulfilled: Sz 98 and Sz 99. These targets display peculiar wind lines in their spectra with multiple velocity components, however, with the lack of a spectro-astrometric outflow signature. Furthermore, we confirm the binary nature of VWCha and CVSO 109. We present (further) evidence that DK Tau B and CVSO 104 A are spectroscopic binaries. Sz 115 is tentatively a spectroscopic binary. We find that the P Cygni line profile in the Hα line is not a robust indicator for the presence of outflows.
Conclusions. The utilised observing strategy (rotating the UVES slit in three different positions) is very powerful in detecting micro-jets in T Tauri stars. The three slit positions can confine the spatial extend of the forbidden emission line regions. The introduced metric to rank targets according to their outflow activity is useful for follow-up observations. The origin of the LVC, that is, MHD winds versus photoevaporative winds, of the Sz 103 and XX Cha microjets remains unclear.